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Title: The Effects of Sodium Metasilicate on Antimicrobial, Sensory, Physical and Chemical Characteristics of Fresh Commercial Chicken Breast Meat Stored at Four Degrees Celsius for Nine Days
Physical Description: 1 online resource (130 p.)
Language: english
Creator: Huang, Huisuo
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2010

Subjects

Subjects / Keywords: antimicrobial, chicken, life, metasilicate, microorganims, pathogenic, poultry, shelf, sodium, spoilage
Animal Sciences -- Dissertations, Academic -- UF
Genre: Animal Sciences thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Marination for meat quality enhancement is an increasingly popular trend in the meat industry. The purpose of this study was to investigate the effectiveness of sodium metasilicate at the USDA approved level and at elevated levels with respect to antimicrobial effect, sensory, chemical and physical characteristics of fresh chicken breast meat stored at 4degreeC for 9 days. Breast fillets were marinated in a vacuum-tumbler (172.32 kPa) with tap water and 1%, 2%, 3% or 4% sodium metasilicate for 20 minutes. Marination yield, pH, water holding capacity, purge loss, cooking yield, total psychrotrophic counts, raw meat color, cooked meat color and texture were evaluated in this study. Sensory evaluation included juiciness, chicken flavor intensity, tenderness and off-flavor using a trained sensory panel. The evaluation of treated raw fillets for 9 days storage revealed that, fillets treated with 3% and 4% sodium metasilicate had higher (P < 0.05) pH and two additional days of shelf life, when compared to control fillets. The cooking yield percentage for fillets treated with 3% sodium metasilicate were higher (P < 0.05), when compared to control fillets. The control fillets and fillets treated with sodium metasilicate were similar (P > 0.05) for purge loss, cooked meat color, instrumental texture, sensory evaluation, and water-holding capacity. When the sodium metasilicate solutions elevated levels up to 4%, the fillets treated with 3% and 4% sodium metasilicate could result in discoloration during the first 3 days of storage, when compared to control fillets. These results suggested that sodium metasilicate at USDA approved levels up to 2% could not sufficiently extend shelf life of raw chicken breast meat. If it were employed in practice, combination with other antimicrobial approaches or increasing the sodium metasilicate levels might be applicable to control microbial growth and extend shelf life.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Huisuo Huang.
Thesis: Thesis (M.S.)--University of Florida, 2010.
Local: Adviser: Williams, Sally K.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2011-08-31

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2010
System ID: UFE0042236:00001

Permanent Link: http://ufdc.ufl.edu/UFE0042236/00001

Material Information

Title: The Effects of Sodium Metasilicate on Antimicrobial, Sensory, Physical and Chemical Characteristics of Fresh Commercial Chicken Breast Meat Stored at Four Degrees Celsius for Nine Days
Physical Description: 1 online resource (130 p.)
Language: english
Creator: Huang, Huisuo
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2010

Subjects

Subjects / Keywords: antimicrobial, chicken, life, metasilicate, microorganims, pathogenic, poultry, shelf, sodium, spoilage
Animal Sciences -- Dissertations, Academic -- UF
Genre: Animal Sciences thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Marination for meat quality enhancement is an increasingly popular trend in the meat industry. The purpose of this study was to investigate the effectiveness of sodium metasilicate at the USDA approved level and at elevated levels with respect to antimicrobial effect, sensory, chemical and physical characteristics of fresh chicken breast meat stored at 4degreeC for 9 days. Breast fillets were marinated in a vacuum-tumbler (172.32 kPa) with tap water and 1%, 2%, 3% or 4% sodium metasilicate for 20 minutes. Marination yield, pH, water holding capacity, purge loss, cooking yield, total psychrotrophic counts, raw meat color, cooked meat color and texture were evaluated in this study. Sensory evaluation included juiciness, chicken flavor intensity, tenderness and off-flavor using a trained sensory panel. The evaluation of treated raw fillets for 9 days storage revealed that, fillets treated with 3% and 4% sodium metasilicate had higher (P < 0.05) pH and two additional days of shelf life, when compared to control fillets. The cooking yield percentage for fillets treated with 3% sodium metasilicate were higher (P < 0.05), when compared to control fillets. The control fillets and fillets treated with sodium metasilicate were similar (P > 0.05) for purge loss, cooked meat color, instrumental texture, sensory evaluation, and water-holding capacity. When the sodium metasilicate solutions elevated levels up to 4%, the fillets treated with 3% and 4% sodium metasilicate could result in discoloration during the first 3 days of storage, when compared to control fillets. These results suggested that sodium metasilicate at USDA approved levels up to 2% could not sufficiently extend shelf life of raw chicken breast meat. If it were employed in practice, combination with other antimicrobial approaches or increasing the sodium metasilicate levels might be applicable to control microbial growth and extend shelf life.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Huisuo Huang.
Thesis: Thesis (M.S.)--University of Florida, 2010.
Local: Adviser: Williams, Sally K.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2011-08-31

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2010
System ID: UFE0042236:00001


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THE EFFECTS OF SODIUM METASILICATE ON ANTIMICROBIAL, SENSORY,
PHYSICAL AND CHEMICAL CHARACTERISTICS OF FRESH COMMERCIAL
CHICKEN BREAST MEAT STORED AT FOUR DEGREES CELSIUS FOR NINE
DAYS

















By

HUISUO HUANG


A THESIS PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF SCIENCE

UNIVERSITY OF FLORIDA

2010

































2010 Huisuo Huang



























To my husband, Yongqiang Yang; my son, Allen Yang; and my parents, Fuxing Huang
and Xiaoyu Wang.









ACKNOWLEDGMENTS

I would like to convey my gratitude to Dr. Sally K. Williams, my major professor, for

her supervision, advice, and guidance from the very early stage of this research as well

as giving me extraordinary experiences throughout the work. She provided her

unflinching encouragement and support in various ways. Appreciation is also expressed

to my committee members, Dr. Amarat Simonne, Dr. Charles A. Sims, for their advice

and support during this project. Their truly scientist intuition exceptionally inspire and

enrich my growth as a student, a researcher and a scientist. I appreciate them more

than they know.

I would like to express special thanks and appreciation to Dr. Gary Eugene

Rodrick for giving me the opportunity to continue my career.

I would like to thank Noufoh Djeri for technical assistance and abundantly help

during the work. I would like to thank her for being the first person who taught me how

to work in this project. I also would like to deeply impress my appreciation to Frank

Robbins Jr., for his assistance and encouragement.

I would like to express gratitude to my husband. This research project would not

have been done without his support. Special thanks to my son, Allen, for his spiritual

support and providing the huge motivation.

I would like to express my love and gratitude to my parents and parents-in-laws for

their understanding and endless love through the duration of this project. I would like to

thank my sisters for their love and support.

Finally, I would like to thank everybody who was important to the successful

realization of thesis, as well as expressing my apology that I could not mention

personally one by one.









TABLE OF CONTENTS

Page

ACKNOW LEDGM ENTS .. ....... ................................................. ............... 4

TABLE OF CONTENTS .................................................................... 5

LIST O F TA BLES .............. ................................ ...... .... .............. 8

LIST OF FIGURES.................................. ......... 11

A B S T R A C T ............. .................. .................. .................................................. 1 2

CHAPTER

1 INTRODUCTION .......... ............................... ... ... ..... ............... 14

2 LITERATURE REVIEW ..................... .............................. 17

Possible Contamination Sources during Broiler Chicken Breast Processing and
C control Strategies ....... ... ............ .. ........................................... .............. 17
S anitary C conditions ............ ...................... .. .............. .... ............... 17
Primary Processing of Broiler Chicken Breast............................... .............. 19
Factors that Affect Microbial Growth on Fresh Broiler Chicken Breast Meat.......... 25
Intrinsic Factors ....... ... ............ .. ........................................... .. .......... 25
Extrinsic Factors ..................... .. .. .. ......... ..... ........................ 27
Spoilage and Pathogenic Microorganisms Associated with Fresh Broiler
Chicken Meat....................... ..... ... .... ...... .. ............................. 28
Spoilage Organisms Associated with Raw Chicken Breast Meat ................ 28
Pathogenic Organisms Associated with Raw Poultry Breast Meat ................ 30
Salm onella ......... .. ...... .......... ........... .. ............................... .......... 31
Cam pylobacter..................... ........ ... ................. ..... .......... 33
Antimicrobials Used in Chicken Breast Meat to Control Pathogenic and
Spoilage Bacteria ......................... .......................................... 34
Chloride ............ ....... ..................... ............... 37
O rganic A cids and Their Salts ........... .... ..... .. ........................... ............... 38
Sodium Tripolyphosphate........................ ............ ..... .......... 41
Sodium M etasilicate .................. ...... ...... ......... ......... ...... 42

3 M ATER IA LS A N D M ETH O D S ......... ................ ....................... .......... .......... 44

Phase I. Preliminary Study: Application Method and Evaluation of Sodium
Metasilicate at Approved Level for Poultry Meat......................... .......... ..... 44
Sample Preparation................................................................ 44
Sample Treatment and Marination Yield ...... .... .......... ............. ............... 44
Experim ent one ............. ..... ...... ...... ........... .......... ...... 44
Experim ent tw o ............... ... ....... ...... ......... ......... ...... 45









pH Analysis ...................................................................... .... ......... ................... 46
Cooking Y ield A nalyses............................... .... ....................... 46
Experiment one: Grill reconstitution method ...... ................................ 46
Experiment two: Oven reconstitution method................ ....... ............... 47
M icrobiological Analyses ............... ....... ................... .... ............ 47
Experiment one ............ .. .................. ......... 47
Experiment two ................................ ......... 48
Objective Color Measurement ................ ....... ..... ......... ............... ............... 49
W arner-Bratzler Shear Force Analysis ........... ............. ....................... 49
Sensory Evaluation Analyses ................ ........... ............. ............... 50
Experim ent one: G rilled fillets ............... ............... ......... ........................ 50
Experim ent tw o: Baked fillets ......... ....................................... ............... 50
Phase II. Preliminary Study: Determination of the Effectiveness of Sodium
Metasilicate at Approved and Elevated Levels and a Shelf Life Study ............... 52
W ater-Holding Capacity Analyses ................................................................. 53
Phase III. Investigation of the Effectiveness of Sodium Metasilicate at the USDA
Approved and Elevated Levels on Antimicrobial, Sensory, Chemical and
Physical Characteristics of Fresh Chicken Breast Meat Stored at 40C for 9
D ays .............. ....... .. .. ......................................................... 54
Sample Preparation............................. ... ......... 54
Sample Treatment and Marination Yield ....... .... ........... ..................... 54
pH Analysis ....................... ... ... ................. 55
Water-Holding Capacity Analyses ......... ......... ........... ............... 56
Purge Loss Analysis ....................................................... 57
Cooking Y ield A nalysis............................................... ..................... 58
Microbiological Analysis .................................. ............... 58
Objective Color M easurem ent .............. .............................................. 59
Warner-Bratzler Shear Force Analysis ............ ................................. 59
S e nso ry E va luatio n ......... ................ ....... ...... ..................... ................ 60
Statistical A analysis ................. ........ .......................... ............... 61

4 RESULTS AND DISCUSSION ............... ........... ......... ....... ..... ...... ......... 62

Phase I. Preliminary Study: Application Method and Evaluation of Sodium
Metasilicate at Approved Level for Poultry Meat..................................... ..... 62
Experim ent 1 ................... .. ........................... ......... .............. 62
M a rinatio n y ie ld a na lysis ................................ ............... .... .. ............... 62
pH and cooking yield analyses.............................................. .. ................... 62
M icrobiological analysis ................ .. ........... ......... .......... ........... 62
Objective color measurement .................... .... ......... ... ............ 63
Sensory evaluation and warner-bratzler shear force analyses................. 64
Experim ent 2 ............... ..... .......................... .... .... .... ........... 64
M a rinatio n y ie ld a na lysis ................................ ............... .... .. ............... 64
pH analysis ................. ......... ............ .. ............... 64
Cooking yield analysis ............. .. ........ .... ................ ........... 65
M icrobiological analysis ................ .. ........... ......... .......... ........... 65
Objective color measure ent ..................... ............. ......... ............ 65


6









W arner-bratzler shear force analysis ........ ........ .................................... 66
S ensory evaluation ................ .. .... ...... .................................. ..... .......... 66
Phase II. Preliminary Study: Determination of the Effectiveness of Sodium
Metasilicate at USDA Approved and Elevated Levels in a Shelf Life Study ........ 67
Marination Yield Analysis ......................._............. .................... 67
pH Analysis .............. ............ ... ................. 68
W ater-Holding Capacity Analyses ............... ........... ......... ........ ............ 68
Water-holding capacity with sodium chloride................................. 68
Water-holding capacity with distilled water. ................................... .. 69
C oo king Y ie ld A na lysis ................................ ............................. 69
M icrobiological A analysis ......................................_......................... 70
Objective Color Measurement .................................. .... ............... 71
R aw fillet co lo r ............. .......... ....... .... ....... ... ............... .......... 7 1
Cooked fillet color ..................... ........... ........... ..... ........... 72
W arner-Bratzler Shear Force Analysis ....... ................. ... ................... 73
S e nso ry E va luatio n ....................................... ................. ..... ............. ... 73
Phase III. Investigation the Effectiveness of Sodium Metasilicate at the USDA
Approved Level and Elevated Levels on Antimicrobial, Sensory, Chemical
and Physical Characteristics of Fresh Chicken Breast Meat and Stored at 4C
for 9 Days .................................................... ................................. 74
M arination yield A analysis ..................................................... .... ..... ......... 74
pH A analysis .................. ................. ........ ..................................... 74
W ater-Holding Capacity Analyses .............................................. ............... 75
Water-holding capacity with sodium chloride. .................................. 75
Water-holding capacity with distilled water. ....................... .............. 75
P u rg e Lo ss A n a lys is ............... ............................................ ................ 76
C oo king Y ie ld A na lysis ................................ ............................. 76
M icrobiological Analysis ................................................. ................. 76
O objective Color M easurem ent ............... .................................... ............... 77
R a w fille t c o lo r ................ ...................................................... 7 7
C ooked fillet color .......................................... .............................. 79
Warner-Bratzler Shear Force Analysis ............... ............................. 80
S e n so ry E v a lu a tio n ............... ............................................................. 8 1
J u ic in e s s .................................................. 8 1
C chicken flavor intensity ............... .................................................... 81
T e n d e rn e ss .................................................. 8 1
O ff-flavor ................................................................. 82

5 SUM M ARY AND CO NCLUSIO N .................................. .................................... 122

LIS T O F R E F E R E N C E S ............... .................................. .......................... 124

BIO G RA PHICAL SKETCH ........................................ ............ ........ ............... 130









LIST OF TABLES


Table page

4-1 Total psychrotrophic counts for boneless and skinless broiler chicken breast
meat marinated with sodium metasilicate and stored at 4C on day 0 ............... 85

4-2 Meat color measurement for boneless and skinless broiler chicken breast
meat marinated with sodium metasilicate and stored at 4C on day 0 ............... 85

4-3 Sensory evaluation and Warner-Bratzler shear force for boneless and
skinless broiler chicken breast meat marinated with sodium metasilicate and
stored at 4 C on day 0 ......................................... ................ .............. 86

4-4 pH measurement for boneless and skinless broiler chicken breast meat
marinated with sodium metasilicate and stored at 4C for 6 days ................. 87

4-5 Total psychrotrophic counts for boneless and skinless broiler chicken breast
meat marinated with sodium metasilicate and stored at 4C for 6 days ............ 88

4-6 Objective raw meat color for boneless and skinless broiler chicken breast
meat marinated with sodium metasilicate and stored at 4C for 3 days ............ 89

4-7 Objective cooked meat color for boneless and skinless broiler chicken breast
meat marinated with sodium metasilicate and stored at 4C for 3 days ............ 90

4-8 Warner-Bratzler shear force for boneless and skinless broiler chicken breast
meat marinated with sodium metasilicate and stored at 4C for 3 days ............ 91

4-9 Panelist rating for boneless and skinless broiler chicken breast meat
marinated with sodium metasilicate and stored at 4C for 3 days ................. 92

4-10 pH measurement for boneless and skinless broiler chicken breast meat
marinated with sodium metasilicate and stored at 4C for 9 days ................. 94

4-11 Water-holding capacity percentages for boneless and skinless broiler chicken
breast meat marinated with sodium metasilicate and stored at 4C for 9 days:
W HC with sodium chloride ..................... ............. .. ... .. ............ 96

4-12 Water-holding capacity percentages for boneless and skinless broiler chicken
breast meat marinated with sodium metasilicate and stored at 4C for 9 days:
W HC with distilled water only .............. ........... ................. .......... .......... 97

4-13 Total psychrotrophic counts for boneless and skinless broiler chicken breast
meat marinated with sodium metasilicate and stored at 4C for 9 days ............ 99

4-14 Objective raw meat color L* values on boneless and skinless broiler chicken
breast meat marinated with sodium metasilicate and stored at 4C for 9 days 100









4-15 Objective raw meat color a* values for boneless and skinless broiler chicken
breast meat marinated with sodium metasilicate and stored at 4C for 9 days 101

4-16 Objective raw meat color b* values for boneless and skinless broiler chicken
breast meat marinated with sodium metasilicate and stored at 4C for 9 days 102

4-17 Objective cooked meat color L* values for boneless and skinless broiler
chicken breast meat marinated with sodium metasilicate and stored at 4C
fo r 9 d a y s................... .................................. ................. 1 0 3

4-18 Objective cooked meat color a* values for boneless and skinless broiler
chicken breast meat marinated with sodium metasilicate and stored at 4C
fo r 9 d a y s................... .................................. ................. 1 0 4

4-19 Objective raw meat color b* values for boneless and skinless broiler chicken
breast meat marinated with sodium metasilicate and stored at 4C for 9 days 105

4-20 Warner-Bratzler shear force for boneless and skinless broiler chicken breast
meat marinated with sodium metasilicate and stored at 4C for 9 days ........... 106

4-21 Panelist rating for juiciness and chicken flavor intensity for boneless and
skinless broiler chicken breast meat marinated with sodium metasilicate and
stored at 4 C for 9 days ............................................................................. 107

4-22 Panelist rating for tenderness and off-flavor for boneless and skinless broiler
chicken breast meat marinated with sodium metasilicate and stored at 4C
fo r 9 d a y s................... .................................. ................. 1 0 8

4-23 Mean pH measurements for boneless and skinless broiler chicken breast
meat marinated with sodium metasilicate and stored at 4C for 9 days ........... 110

4-24 Mean water-holding capacity percentages for boneless and skinless broiler
chicken breast meat marinated with sodium metasilicate and stored at 4C
for 9 days: WHC with sodium chloride and distilled water ...... ........................ 111

4-25 Mean purge loss percentages for boneless and skinless broiler chicken
breast meat marinated with sodium metasilicate and stored at 4C for 9 days 112

4-26 Mean cooking yield percentages for boneless and skinless broiler chicken
breast meat marinated with sodium metasilicate and stored at 4C for 6 days 113

4-27 Mean total psychrotrophic counts for boneless and skinless broiler chicken
breast meat marinated with sodium metasilicate and stored at 4C for 9 days 114

4-28 Mean objective raw meat color L* values for boneless and skinless broiler
chicken breast meat marinated with sodium metasilicate and stored at 4C
fo r 9 d a y s. .................. .................................. ................. 1 1 5









4-29 Mean objective raw meat color a* values for boneless and skinless broiler
chicken breast meat marinated with sodium metasilicate and stored at 4C
fo r 9 d a y s. .................. .................................. ................. 1 1 6

4-30 Mean objective raw meat color b* values for boneless and skinless broiler
chicken breast meat marinated with sodium metasilicate and stored at 4C
fo r 9 d a y s. .................. .................................. ................. 1 1 7

4-31 Mean cooked meat color for boneless and skinless broiler chicken breast
meat marinated with sodium metasilicate and stored at 4C for 6 days ........... 118

4-32 Mean Warner-Bratzler shear force for boneless and skinless broiler chicken
breast meat marinated with sodium metasilicate and stored at 4C for 6 days 119

4-33 Panelist rating for juiciness and chicken flavor intensity for boneless and
skinless broiler chicken breast meat marinated with sodium metasilicate and
stored at 4 C for 6 days ............................................................................. 120

4-34 Panelist rating for tenderness and off-flavor for boneless and skinless broiler
chicken breast meat marinated with sodium metasilicate and stored at 4C
fo r 6 d a y s. .................. .................................. ................. 1 2 1









LIST OF FIGURES


Figure
page
4-1 Marination yield percentages for boneless and skinless broiler chicken breast
meat marinated with sodium metasilicate and stored at 4C on day 0 ............... 83

4-2 pH value for boneless and skinless broiler chicken breast meat marinated
with sodium metasilicate and stored at 4C on day 0 ....................... ........ .. 83

4-3 pH of marinade solutions for boneless and skinless broiler chicken breast
meat marinated with sodium metasilicate and stored at 40C on day 0 ............... 84

4-4 Cooking yield percentages for boneless and skinless broiler chicken breast
meat marinated with sodium metasilicate and stored at 4C on day 0 ............... 84

4-5 Marination yield percentages for boneless and skinless broiler chicken breast
meat marinated with sodium metasilicate and stored at 4C for 6 days ............ 86

4-6 Cooking yield percentages for boneless and skinless broiler chicken breast
meat marinated with sodium metasilicate and stored at 40C for 6 days ............ 87

4-7 Marination yield percentages for boneless and skinless broiler chicken breast
meat marinated with sodium metasilicate and stored at 40C for 9 days ............ 93

4-8 Marinade solution of pH for boneless and skinless broiler chicken breast
meat marinated with sodium metasilicate and stored at 40C on day 0 ............... 95

4-9 Cooking yield percentages for boneless and skinless broiler chicken breast
meat marinated with sodium metasilicate and stored at 40C for 9 days ............ 98

4-10 Marination yield percentages for boneless and skinless broiler chicken breast
meat marinated with sodium metasilicate and stored at 40C for 9 days ........... 109









Abstract of Thesis Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Master of Science

THE EFFECTS OF SODIUM METASILICATE ON ANTIMICROBIAL, SENSORY,
PHYSICAL AND CHEMICAL CHARACTERISTICS OF FRESH COMMERCIAL
CHICKEN BREAST MEAT STORED AT FOUR DEGREES CELSIUS FOR NINE DAYS

By

Huisuo Huang

August 2010

Chair: Sally K. Williams
Major: Animal Sciences

Marination for meat quality enhancement is an increasingly popular trend in the

meat industry. The purpose of this study was to investigate the effectiveness of sodium

metasilicate at the USDA approved level and at elevated levels with respect to

antimicrobial effect, sensory, chemical and physical characteristics of fresh chicken

breast meat stored at 40C for 9 days. Breast fillets were marinated in a vacuum-tumbler

(172.32 kPa) with tap water and 1%, 2%, 3% or 4% sodium metasilicate for 20 minutes.

Marination yield, pH, water holding capacity, purge loss, cooking yield, total

psychrotrophic counts, raw meat color, cooked meat color and texture were evaluated in

this study. Sensory evaluation included juiciness, chicken flavor intensity, tenderness

and off-flavor using a trained sensory panel. The evaluation of treated raw fillets for 9

days storage revealed that, fillets treated with 3% and 4% sodium metasilicate had

higher (P < 0.05) pH and two additional days of shelf life, when compared to control

fillets. The cooking yield percentage for fillets treated with 3% sodium metasilicate were

higher (P < 0.05), when compared to control fillets. The control fillets and fillets treated

with sodium metasilicate were similar (P > 0.05) for purge loss, cooked meat color,









instrumental texture, sensory evaluation, and water-holding capacity. When the sodium

metasilicate solutions elevated levels up to 4%, the fillets treated with 3% and 4%

sodium metasilicate could result in discoloration during the first 3 days of storage, when

compared to control fillets. These results suggested that sodium metasilicate at USDA

approved levels up to 2% could not sufficiently extend shelf life of raw chicken breast

meat. If it were employed in practice, combination with other antimicrobial approaches

or increasing the sodium metasilicate levels might be applicable to control microbial

growth and extend shelf life.









CHAPTER 1
INTRODUCTION

Poultry meat and products are important components of diets in the United States.

The annual per capital consumption continues to increase each year and has for

decades. Chickens contribute seventy to 80% of the annual consumption, while turkeys

contribute to only 19% (International Commission on Microbiological Specification for

Foods, ICMSF, 1998). Total meat per capital consumption (red meat and poultry) in

2007 was 100.7 kilograms. Of these meat, 53.2 kilograms were contributed by red

meat, whereas, 47.5 kilograms was from poultry. Meat consumption has significantly

increased since 1975, where only 21.5 kilograms poultry meat was consumed per

capital (Laux, 2009; USDA, 2009).

Consumers prefer purchasing skinless or boneless poultry parts and further

processed products instead of the whole carcasses. For example, approximately 90% of

poultry meat in the United States is sold as parts or further processed products (Young

and Lyon, 1997). Consumers are especially interested in chicken parts due to the

convenience and nutritional value, such as chicken breast meat (Seabra et al., 2001).

Broiler breast meat is considered the premium part in the United States (Saha et al.,

2009). Due to the uneven geographic distribution of poultry producers in the USA, most

poultry plants are located in the southeast. Therefore, raw poultry products require

transportation from the southeast of the U.S. to other districts in order to provide fresh

poultry (Russell, 1998; Angella, 1999). A major problem with extensive transporting of

raw poultry is that the natural properties of chicken provide an excellent substrate for

microbial growth and raw poultry meat is a highly perishable commodity (Russell, 1998;

White, 2000; Mead, 2004). The safety of poultry directly impacts the public health and









economy. Therefore, the requiring intervention strategies that could prolong shelf life of

poultry and poultry products are of major concern to the government, corporation and

consumers (Johny et al., 2008).

More than 1.4 million cases of nontyphoid salmonellosis and 2.4 million cases of

Campylobacter infection were reported annually in the United States. The money spent

for Salmonella and Campylobacter related illnesses associated with poultry were

approximately $ 64 million to $ 114.6 million, and $ 362 million to $ 699 million,

respectively (Altekruse et al., 1999; Johny et al., 2008). Inadequate cooking, time and

temperature abuse, and cross-contamination obtained from raw poultry products are

major contributors to the primary reasons of foodborne illness outbreak.

Cunningham and Cox (1987) stressed that "anything that contacts a single bird

might lead to contamination and anything that contacts more than one bird might have

cross-contamination". Jay (1992) reported that intrinsic parameters and extrinsic

parameters associated with poultry could determine microbial load and types. Any

technologies that could modify these factors could extend shelf life of poultry products.

Numerous approaches that have been investigated can be divided into chemical,

physical and a combination of chemical and physical methods (Bolder, 1997). Each step

in poultry processing, from farm to ready-to-cook product, may be factors that influence

the microbial load and types.

Various antimicrobial chemicals have been employed into the poultry processing

line. For instance, organic acids are used to wash, rinse and spray to clean carcasses

and to reduce numbers of microorganisms. Other antimicrobial chemicals such as

alternative chlorine and phosphate using in scalding water and spraying also have been









investigated to affect the shelf life and poultry quality. Another process that may be

applied to introduce chemical antimicrobials is called marination which included vacuum

tumbling, injection or combination methods. In this literature review, the source of

contamination during poultry processing, control methods to reduce microbial load;

factors that determine the microbial quality of poultry meat; the microorganisms

associated with poultry; mechanisms of action and effect of chlorine, organic acids and

salts, acidified sodium chlorite, and sodium tripolyphosphate on sensory characteristics

and the functional possibilities of applying sodium metasilicate, which shares some

similarities with sodium tripolyphosphate, will be discussed.









CHAPTER 2
LITERATURE REVIEW

Possible Contamination Sources during Broiler Chicken Breast Processing and
Control Strategies

Sanitary Conditions

The numbers and types of microorganisms present in fresh chicken carcasses

mainly contribute to four sources: (1) original flora of microorganisms in the raw chicken;

(2) sanitary conditions around products such as wall surfaces, equipment, transfer

machine, air and handlers; (3) control measures utilized during processing; and (4)

sanitary conditions during packaging, handling and storage (Pearson and Dutson, 1994;

Mead, 2007). Initial contamination generally results from live birds even healthy

chickens. A healthy live bird carries several kinds of microorganisms on its skin,

feathers, and in its intestinal tract. The microbial population of poultry carcasses could

be generally divided into three types: the natural flora of skin; the transient flora,

attached on the skin and feathers, which could be easily removed during slaughter

processing; and obtained organisms during processing, it is generally called cross-

contamination. Carcasses may be contaminated due to contact with equipment, tools,

hands or gloves of workers and contaminated birds (Cunningham and Cox, 1987;

ICMSF, 1998). However, most natural floras have no detrimental effect on consumers.

But if control measurements are not used appropriately or efficiently, natural floras will

decrease product quality (Russell, 1997).

The finished products that contained amounts and types of organisms were

dependent on processing practices (Pearson and Dutson, 1994). Some microorganisms

can be transmitted from the intestines of parent chicken to its offspring. Live healthy

birds may get infected by contacting with the contaminated eggs, net materials and









incubators. Additionally, air current may spread microorganisms among hatcheries

(ICMSF, 1998). Besides, the healthy chicken may be contaminated by the feeding food

and drinking water. Feeding food may contain animal protein ingredients, and drinking

water may be contaminated by dust, litter, feathers, feet and feces. Rodents and

cockroaches may spread microorganisms within the poultry flock. Also workers may

spread pathogens through their shoes within flocks as well (ICMSF, 1998). Hence, live

birds may arrive at the processing plant with various bacteria from both the external and

internal part of chicken bodies (Bolder, 1997; Russell, 1997). There are some

possibilities that any of these microorganisms could be the sources of contamination of

the final products (Mead, 2004).

Spoilage bacteria, mainly Achromobacter (Acinetobacter), Corynebacterium, and

Flavobacterium, were detected in the respiratory systems of fresh broiler chickens.

These microorganisms were detected on feathers, feet of live chickens, water and feed

supply, and equipment in the processing plant (Russell, 1997; Russell, 1998). However,

the number of spoilage organisms significantly declined after scalding. Cunningham and

Cox (1987) reported that Pseudomonas, primarily detected in eviscerated spoiled

chicken, could not be isolated in the respiratory system or in the intestinal tract after

washing. The potential pathogens derived from the intestine of live chickens, which

Salmonella spp., Campylobacter spp., Listeria spp., E. coli 0157:H7 and

Staphylococcus are of concern to processors (Bolder, 1997). If the processing plant

practices do not efficiently manage the spread of microorganisms, then final meat

quality and shelf life could be significantly affected (Russell, 1997). The presence of

bacteria and spreading routes depend on plant hygiene conditions during harvest,









slaughter, processing, storage, distribution and preparation (Russell, 1997; Mead,

2004).

Primary Processing of Broiler Chicken Breast

Mead (2004) concluded that the processing flow, which involved from live broiler

chicken to ready-to-cook chicken products, could be classified into four steps. The first

step includes receiving and hanging the live broilers. The second step is considered the

dirty processing (Mead, 2004), which includes stunning, slaughter, bleeding, and

defeathering (scalding, picking and washing). The elements of the third step are

evisceration (viscera removal, offal) and carcass washing. The fourth step involves

chilling, grading, packaging, shipping, and may include further processing (Cunningham

and Cox, 1987; ICMSF, 1998; Mead, 2004). Mead (2004) pointed out that the types

and population of microorganisms on the final chicken products were chiefly dependent

on the microbial state of the live broiler chicken. Since the plant producers cannot

assure eradication of all pathogens during processing, it is important to control the

pathogenic organisms on the farm. Vaccinating the birds and maintaining a clean

environment are regarded as the best strategies to reduce the opportunity for vertical

contamination of pathogenic microorganisms.

The principal genera of microorganisms could be detected in the intestinal system

and respiratory system of the healthy broiler chicken. In the intestinal system, the

organisms include Lactobacillus, Corynebacterium, Escherichia coli, Streptococcus

faecalis, and Clostridium perfringens. The respiratory system of healthy birds contains

Streptococcus, Staphylococcus, Corynebacterium, Lactobacillus, Escherichia, and

Bacillus. The psychrotrophic bacteria that could be found on the feet, skin, and feathers

of live chicken are Flavobacterium, Achromobacter, and Corynebacterium. However,









after scalding, the psychrotrophic organisms would be dramatically diminished.

Pseudomonas is not commonly detected in scalding water since it does not exist on the

live chicken (Cunningham and Cox, 1987)

After unloading birds to the processing plant, E. coli numbers were higher on the

chicken breast surface compared with that prior to loading (Mead, 1989). Marin and

Lainez (2009) reported that the colonization of Salmonella after transportation to the

abattoirs was strikingly amplified. Some researchers concluded that stress during

loading and transportation may accelerate the spread of bacteria (Mead, 1989;

Richardson and Mead, 1999). During hanging chicken on the shackle, a majority of

chickens may struggle and flap their wings causing dust, feathers and litter to fall down,

which may lead to scatter dust and spread microorganisms. Mead (1989) also reported

that Salmonellas and Staphylococcus aureus were easily detected in the air of the

unloading compartment. So the effective method preventing spreading bacteria was to

separate the unloading truck from the other following processing.

Traditional stunning birds with electrical shock and then bleeding carcasses have

been reported to have an insignificantly influence on the final product regarding

microbial quality (ICMSF, 1998). After stunning, the neck cutting machines, with one or

two blades commonly used in the poultry industry, will detach the carotid vein and artery

on each side of the neck. The advantage of this method is to remove the esophagus

and trachea during evisceration processing (Mead, 2004). The next step is defeathering

which contains scalding, picking and washing. Methods of scalding include hot water

immersion, hot water spray, steam, and combination of hot water spray and

defeathering (ICMSF, 1998). In general, hot water immersion scalding is the most









common in industry. The time and temperature of scalding water was determined by the

appearance of the required product and chilling method (ICMSF, 1998). For example,

turkeys are usually hard scalded to maintain the white skin appearance. In industry,

chickens are soft scalded when meat is sold fresh due to the unappealing color

developed when using hard scald.

The primary purpose of scalding is to readily remove feathers when plucking, but

the microbial effect cannot be ignored during scalding process. After scalding,

microorganisms are detected in the water tank. These microorganisms come from skin,

feathers, and intestinal tracts of birds. Several bacteria could be isolated from the

scalding water or from the carcass immediately after scalding, such as Clostridium,

Micrococcus, Proteus, Pseudomonas, Salmonella, Staphylococcus, and Streptococcus

(ICMSF, 1998). However, Mead (2007) stated that Salmonella was not frequently

isolated from scalding water, and Pseudomonas was easily inactivated at any scalding

temperature. When scalding water was maintained at 58C to 60C, it was not a major

source of contamination (Pearson and Dutson, 1994). Furthermore, experimental

evidence also proved the theory that a scalding water temperature of more than 60C

could reduce a larger number of bacteria than a lower temperature (Cunningham and

Cox, 1987; Mead, 2004). ICMSF (1998) reported that salmonellae were not detected

on chicken carcasses after scalding at 60 C for 200 seconds, but at 55 C for 105

seconds. Brotsky and Bender (1991) stressed that the external and internal Salmonella

of carcasses could be reduced by adjusting the pH value of scalding hot water to

approximately 9.0. Cross-contamination can be reduced by adjusting the scalding water

temperature, scalding time and water pH (ICMSF, 1998; Mead, 2004).









Subsequent to the scalding step, psychrotrophic bacteria were dramatically

diminished. Pseudomonades were not usually detected in scald water (Cunningham

and Cox, 1987). Therefore, scalding was not the significant source of the contamination

of spoilage microorganisms, nor the best step to control propagation of Campylobacter

jejuni (ICMSF, 1998). Alternative interventions such as steam with hot water scalding

and three tank systems with hyperchlorination solution could control cross-

contamination. Nevertheless, it is not practical in industry because these methods

could produce discoloration of carcasses (Mead, 2004; ICMSF, 1998; Davies and

Board, 1992).

In contrast, cross-contamination was of most concern during the defeathering and

evisceration processing (Pearson and Dutson, 1994). There are machines that

employed rotating rubber fingers to release feathers from carcasses, however, if the

rubber fingers fail to release the feathers, the feathers from the rubber fingers will

harbor microorganisms and be difficult to clean. The rubber fingers deteriorate easily

due to high line operating speed. Hence, the rubber fingers would become the source of

spreading microbial to carcasses. In addition, aerobic plate counts and staphylococcal

counts, rather than psychrotrophic spoilage bacteria counts, were higher after

defeathering (ICMSF, 1998; Mead, 1989). Research reported that strains of

Staphylococcus aureus attached to the machine became resistant to low concentrations

of chlorine. Afterwards, bacteria became indigenous to the machines and were difficult

to eliminate. The best method to control the contamination during defeathering and

evisceration was cleaning with a higher level of chlorine before disinfecting, also

frequently altering rubber fingers and preventing feathers from depositing into the









machine. Furthermore, the infection of Salmonellae, Campylobacter and E.coli 0157:

H7 organisms spread from few carcasses to many carcasses in the early step of

feathering processing. In later stages, microorganisms may penetrate into muscles and

are hard to get rid of. Therefore, defeathering was the major step to cause carcass

contamination (Mead, 1989). The population of microorganisms after defeathering could

predict microbial load, and quality of poultry carcass to some degree (ICMSF, 1998).

The third step included evisceration and washing the carcass. During evisceration,

carcasses may become cross-contaminated from the hands of workers, carcasses to

equipment or tools, then to the rest of the carcasses (ICMSF, 1998; Russell, 1997).

Mead (2004) demonstrated that psychrotrophic bacteria contamination could take place

during evisceration because Pseudomonades could spread from gloves to carcasses.

The psychrotrophic pathogens, like Listeria monocytogenes, could attach to the

evisceration apparatus (Mead, 2004). Spraying carcasses with water after defeathering

and evisceration could get rid of organic substances and microorganisms gained during

evisceration. Spraying carcasses many times after evisceration could decrease

population of Salmonella and Enterobacteriaceae compared to spraying carcasses a

single time (ICMSF, 1998). Eviscerated poultry may carry a high population of

Salmonella. Salmonella attached on the carcasses surface involved multiplication

sequence, transmitted to equipment, hands or other surfaces. In spite of this, water

spraying could eliminate Salmonella (Brotsky and Bender, 1991) and also could reduce

aerobic plate counts, Enterobacteriaceae and coliforms by 50 to 90%, respectively

(ICMSF, 1998). However, some Pseudomonas spp. may disperse among carcasses

during spraying. Studies concluded that spraying carcasses with organic acid or









chlorine did not inhibit the cross contamination, and it could not prolong the shelf life of

fresh poultry meat (ICMSF, 1998), because the chlorine solutions immediately fell down

from the carcasses, and this reduced the effectiveness of the chemical compounds

(Mead, 2004; Northcutt et al., 2005).

The forth step included chilling, grading, packaging and transporting, as well as

possibility of further processing. After evisceration, chilling was a valuable step to slow

the growth rate of spoilage microorganisms and to manipulate pathogenic microbial

growth (ICMSF, 1998; Mead, 2004). Most pathogenic organisms cannot generally grow

below 6C, but psychrotrophic bacteria could multiply at below 0C. Common chilling

processes were air chilling (dry chilling), wet chilling and combination chilling. Which

chilling method used depended on how the meat was sold. It may be sold as a whole

carcass, portioned or deboned meat like chicken breast meat. Raw chicken breast meat

was sold wet fresh or frozen; therefore, wet chilling processing would be used. If raw

broiler chicken breast meat was chilled by air, the discoloration would appear and impair

the meat quality. Meat without normal surface color could not be accepted by producers

and consumers. For raw chicken meat, the most common wet chilling methods were

water-immersion chilling and spray chilling (ICMSF, 1998; Mead, 2004). After chilling

processing, no further growth of mesophile organisms should be detected. However, a

time delay in the transfer of carcasses to chill storage would tolerate growth of

psychrotrophic organisms (Mead, 1989). Further cross-contamination could be related

to handling, incising whole carcasses, deboning and circumstances related to

packaging.









The long shelf life of meat can be determined by monitoring the growth of

psychrotrophic microorganisms. Therefore, keeping hygienic conditions of equipment,

carrying out sanitation specifications, maintaining the appropriate storage temperature

and properly holding of products were of great importance to assure the quality of the

chicken breast (ICMSF, 1998; Russell, 1998; Mead, 2004). Blackburn (2006) concluded

that the current methods of controlling cross-contamination of microorganisms in

slaughterhouses, during processing and package were contingent upon fulfilling the

hygienic standards of Good Manufacturing Practices (GMP) at farms, Good Hygienic

Practices (GHP), animal husbandry practices, and carrying out the HACCP system.

Factors that Affect Microbial Growth on Fresh Broiler Chicken Breast Meat

Intrinsic Factors

Raw fresh broiler chicken meat provides good substrate for bacteria growth due to

the biological and chemical composition of chicken meat. Bacteria growth on broiler

chicken is determined by inherent properties of chicken meat as well as external

circumstances around chicken meat. Inherent parameters are moisture content, water

activity or available water, pH or total acidity, oxidation-reduction potential (Eh), nutrient

content, and the biological structure of raw chicken (George, 1989; Michael et al.,

2001). Temperature and gas conditions during storage and distribution are considered

to be the key extrinsic factors that affect the shelf life of raw fresh chicken meat

(Pearson and Dutson, 1994). The combination of intrinsic factors and extrinsic factors

could determine the shelf life and quality of fresh chicken breast meat.

The protein-rich poultry meat could provide a faster microbial growth environment

than those with lower protein meat. The water content of raw broiler chicken meat is

around 74%. Protein and fat content are approximately 23% and 2%, respectively









(Qiao, et al., 2002). Wattanachant et al. (2004) analyzed the biceps femoris and

pectoralis muscles of Thailand broiler chicken meat and calculated protein content to be

around 20%, fat content to be lower than 1%, moisture content to be around 75%, and

pH to be 5.9 to 6.6 for muscle samples. The water activity for poultry meat is about 0.98

to 0.99 which is based on storage environment and storage time (ICMSF, 1998).

Slaughter processing and other operations also could impinge on intrinsic factors, such

as the pH of chicken breast meat would fall in the range of 5.7 to 5.9, and the PSE

(pale, soft, exudative) chicken meat color, caused by the poor practice and high stress

of bird, is darker than normal meat. The pH of the PSE is lower than that of normal

chicken breasts, because of rapid lactic acid accumulation in a short time (Stringer and

Colin, 2000). In additional, food ingredients added to meat could change the pH and

water activity, such as acid flavoring seasonings. Pathogenic microorganisms require a

slightly acidic pH level of 4.6-7.5. The pH value of chicken breast meat has an optimum

acid tolerance level for the spoilage organisms and pathogen organisms to grow

(ICMSF, 1998; White, 2000; ServSafe Essential 5th, 2006). For example, the minimum

pH for Salmonella and Pseudomonas growth are 4.0 and 5.5, respectively. So if

ingredients alter muscle pH to the optimum acidity condition, the type and rate of

microbial proliferation would change. Environmental redox potential is an important

determinant of microbial growth. Aerobic microorganisms required positive redox

potential value, while anaerobes required negative redox value. The redox potential of

poultry was reported to range from -150 mV to +250 mV and has similar level with beef,

pork and lamb (ICMSF, 1998). Biological structure of poultry meat is also susceptible to

microbial growth. Many microbes reside under the skin of poultry providing more









occasions to assault the muscle. Thus, skin and muscle tissue of poultry provide good

substrates for bacteria growth (ICMSF, 1998).

Extrinsic Factors

In additional to intrinsic parameters that could affect the rate and extent of

microbial growth, extrinsic factors influence growth of microorganisms as well.

Therefore, the combination of factors could be determinants of the shelf life of meat.

The extrinsic factors include storage environment such as storage temperature and

time, relative humidity of the environment, and the presence and concentration of gas

around chicken meat in package, and antimicrobials added (Stringer and Colin, 2000).

Storage time could affect the population of microorganisms and the temperature could

affect the multiplication and rate of microorganisms. For example, psychrotrophic

bacteria have higher adaption under chill conditions. So, improper storage temperature

is the most important factor affecting perishability of meat, especially in muscle meat.

The rate of spoilage of fresh poultry at 10C is about twice that at storage of 5C, and

that 15C storage is about three times faster than the when the storage temperature is

5C (Jay, 1992). Pearson and Dutson (1994) reported the same conclusion that the

mean shelf life at OC is 14 days, and when the storage time increases to 5C, storage

days are reduced to 7 days, and so on. During the high humidity of refrigerator storage,

the meat spoilage microorganism is mainly psychrotrophic bacteria. These organisms

grow well under the chilled condition and cause meat spoilage. Studies also revealed

that vacuum and gas atmosphere storage could delay the spoilage of poultry. When

compared with raw poultry stored in oxygen permeable film, vacuum package, and

carbon dioxide flushed high-barrier film, the shelf life was 9 days, 10 days and 17 days,

respectively (Jay, 1992).









Spoilage and Pathogenic Microorganisms Associated with Fresh Broiler Chicken
Meat

The bacteria harbored on poultry could be divided into pathogens (causing

foodborne disease after food consumption) and non-pathogens (not associated with

disease). Most nonpathogenic organisms, also called spoilage organisms, are still a

concern of producers since spoilage organism could produce off flavor, discoloration

and cause undesirable texture in the meat (Cunningham and Cox, 1987; White, 2000).

Pathogenic microorganisms associated with fresh poultry are Salmonella,

Campylobacter, Clostridium perfringens, Staphylococcus aureus, Listeria

monocytogenes and Clostridium botulinum (ICMSF, 1998; White, 2000; Mead, 2004).

Controlling growth of Salmonella Enteritis and Campylobacterjejuni continue to be the

major concerns for the poultry industry in the USA. The United States Department of

Agriculture (USDA) made a regulation that the maximum level of Salmonella allowed in

poultry carcasses is 10% (Bauermeister et al., 2008). More efforts should be performed

to reduce cross-contamination during processing.

Spoilage Organisms Associated with Raw Chicken Breast Meat

The initial bacteria of raw poultry meat are mesophile microorganisms (Saucier et

al., 2000). Immediately after processing, the isolated bacteria from fresh chicken

carcasses were Micrococcus (50%), gram-positive rods (14%), Flavobacteria (14%),

Enterobacteriaceae (8%), Pseudomonas (2%), Acinetobacter (7%), and unknown

genera (5%). Of these, only Pseudomonas and Acinetobacter grow faster at

refrigeration storage for 10 days, and 90% of the bacterial species were Pseudomonas

fluorescens in the later storage time (Russell, 2000; Charles et al. 2006; Mead, 2007).

Under refrigeration storage conditions, organisms generated fastest during refrigeration









conditions, are termed psychrotrophic. The psychrotrophic microorganisms grow well at

below 7C and produce visible colonies at 7C for 10 days, and the optimum

temperature growth is between 20C and 30C (Jay, 1992). The primary species of

psychrotrophic microorganisms is Pseudomonas in fresh refrigerated poultry meat and

mainly Pseudomonas fluorescens, Pseudomonas putida and pseudomonas fragi

(White, 2000; Blackburn, 2006). Pseudomonas organisms cannot grow under vacuum

and adequate carbon dioxide conditions. They can proliferate under aerobic and less

than 20% carbon dioxide storage. Other characteristics of Pseudomonas are formation

of off-flavor and surface stickiness.

At the beginning of spoilage, the microorganisms exhaust glucose till completely

depleted, and then degrade the small compounds, like amino acids. Prior to slime

formation, the metabolism of amino acids release off-flavor substances. Later, colonies

appear on the surface of meat. Finally, colonies grow together and develop a coat on

the meat. The off-flavor could be detected when counts are up to 7- 8 log ioCFU/g, and

the slime and sticky coat could be detected when the counts are over 8 log ioCFU/g.

Russell (1998) explained that the dominant bacteria that produced off-odor were

Shewanella putrefaciens, Pseudomonas fluorescens, and Pseudomonas putida.

Previous studies also demonstrated that majority of bacterial species on poultry meat in

the later stage of storage were Pseudomonas fluorescens. Russell (1997) reported that

the sulfur compound from off flavor in poultry meat was mainly produced by

Pseudomonas and Shewanella spoilage bacterial.

Methods that measure spoilage in poultry include chemical methods (such as

discoloration, release of gas, or chemical contents), physical methods (such as pH









value change, surface tension), bacteriological and physiochemical methods. For

example, Jay (1992) pointed out that the total psychrotrophic counts and water holding

capacity could be indicators of meat spoilage.

Pathogenic Organisms Associated with Raw Poultry Breast Meat.

Poultry products are a common media for foodborne illness outbreaks (ICMSF,

1998), because inappropriately cooling and heating, time and temperature abuse,

undercooking, improper handling of raw poultry meat and cross contamination are

fundamental factors that lead to outbreak of foodborne illness. Pathogenic bacteria

associated with poultry meat are Salmonella enteritidis, Campylobacterjejuni,

Clostridium perfringens, Staphylococcus aureus, Listeria monocytogenes (ICMSF,

1998; White, 2000; Mead, 2004). Salmonella Enteritidis may be found in the intestinal

tracts of warm-blooded animals such as poultry meat and egg products. Campylobacter

jejuni is one of the most common sources that cause diarrheal illness in humans.

Monitoring cross-contamination and not consuming undercooked poultry meat could

reduce infection of this disease. Food poisoning due to Clostridium perfringens is mainly

associated with improper storage of cooked turkey. Staphylococcus aureus has been

isolated on human hands, and ready to eat food such as chicken salad. "Live poultry

can carry Staphylococci in bruised tissue, infected lesions, inside of nasal, arthritic joint,

and on breast meat surface" (ICMSF, 1998). Most of the original staphylococci

organisms on birds are damaged after scalding, however, the birds are infected by

Staphylococcus aureus from defeathering machine. Staphylococcus aureus isolated

from poultry are never been reported causing the serious foodborne outbreak, and

under low temperature storage conditions, Staphylococcus aureus is a poor competitor

with other spoilage organisms on raw meat and poultry. The majority of Staphylococcus









aureus foodborne illness associated with poultry is due to the improper handling of the

cooked poultry product. Therefore, Staphylococcus aureus is not a concern for public

health (ICMSF, 1998). Listeria monocytogenes is often present on raw meat, and can

be destroyed by cooking, but poor hygiene practices still can cause consumer

foodborne illness. However, there is no evidence shown that Listeria monocytogenes

multiplication on raw meat is the primary causative of listeriosis foodborne illness

outbreak. Therefore, Listeria monocytogenes is generally associated with cooked and

ready to eat poultry products. By far, Salmonellae and Campylobacter are the most

important pathogens associated with raw poultry product (ICMSF, 1998).

Salmonella

Salmonella is a gram-negative, facultative anaerobic, non-spore forming, and rod-

shaped bacteria. The majority of Salmonella species can move by peritrichous flagella.

USDA (2009) reported that "Salmonella is a member of the family Enterobacteriaceae,

many of them can cause human illness and they are catalase positive, oxidase

negative, and hemoorganotrophic. Salmonella has the ability to metabolize nutrients by

both respiratory and fermentative routes". It comprises two species: Salmonella bongori

and Salmonella enterica. Salmonella enterica causes intestinal disease, and could be

isolated from human and warm-blooded animals. Salmonella enterica account for more

than 99.5% of serotypes. S. typhi, S. typhimurium and S. enteritidis are three main

serovars of S. enterica. S. enteritidis is the most common sources of foodborne illness

in the United States. Vertical and horizontal transmissions of Salmonella are the primary

pathways of cross-contamination in poultry plants. Scientists have identified more than

2,400 serotypes of the genes Salmonella bacteria. Of these, two serotypes are specific

poultry pathogens (S. gallinarum and S. pullorum) (Breytenbach, 2004; Revolledo et al.,









2009). Paratyphoid Salmonella (S. enteritidis, S. typhimurium, and S. typhi) have a wide

host range and could not lead to poultry disease, but these serotype pathogens are of

major concern for public health. Salmonella outbreaks cost an estimated $3 billion

annually in the United States.

Salmonella is named after Dr. D. E. Salmon in 1900. He, along with his coworkers,

was the first person to observe and report the characteristics of Salmonella

Choleraesuis. Since 1933, the term Salmonella has prevailed (Cunningham and Cox,

1987). Salmonella growth range is 7C to 47C, the optimum growth temperature range

being 35C to 37C, which is close to body temperature. If the temperature is below

6.7C, the growth of Salmonella could be prevented. Temperature over 70C could kill

Salmonella, and refrigeration temperature prevents the growth of Salmonella but will not

kill them (ICMSF, 1998; White, 2000). Salmonella can grow between pH values from 4.0

to 9.0 and the optimum pH range is 6.5 to 7.5 (White, 2000). Jay (1992) reported that

the best pH for Salmonella growth is between 6.6 and 8.2. The minimal water activity for

growth of Salmonella was about 0.94 (White, 2000).

Live poultry are the primary reservoir of Salmonella bacteria. Some organisms on

the carcasses surface may spread to other carcasses during processing, packing,

distribution and holding and further processing. There are mainly three routes of

Salmonella cross-contamination: first, feed and drinking water; second, birds get

infected by vertical transmission, namely, from contaminated eggs to their offspring;

and the third vehicle is called horizontal transmission, which means that healthy poultry

is contaminated by other carcasses, or equipment, tools, workers and other animals

(Mead, 2004). Researchers concluded that Salmonella horizontal transmission could be









the major determinant of the final microbial load and types on meat products. However,

the initial source associated with poultry is feeding contaminated water and food

(Cunningham and Cox, 1987; Mead, 2004). One unique characteristic of some

Salmonella strains is the ability to penetrate from chicken skin to inside organs of

chicken (Mead, 2004). An infectious dose of Salmonella on poultry carcass is small,

probably from 15 to 20 cells, but sometimes more than 14 log ioCFU/g of skin occurred

(ICMSF, 1998). However, a low dose level of Salmonella ingesting contaminated meat

might be lethal.

Control methods employed in industry are to avoid cross-contamination between

flocks and to provide poultry vaccination on farm. The control recommendation methods

for producers are to keep carcass Salmonella free, avoid feeding contaminated food

and water, and prevent cross-contamination between carcasses. For consumers and

retailers, improper cooling, holding, reheating, and undercooking contribute to

Salmonellosis outbreaks (Cunningham and Cox, 1987).

Campylobacter

The Campylobacter species has been considered the main common sources of

human bacterial gastroenteritis in the United States (Isohanni and Lyhs, 2009). Egg and

poultry products are the primary sources of C. jejuni (ICMSF, 1998; Mead, 2004). The

most important risk of Campylobacteriosis is to consume undercooked poultry meat or

to mishandle raw poultry meat (Isohanni and Lyhs, 2009; Nather et al., 2009). Once

birds get infected, Campylobacter spp. spread fast (Nather et al., 2009). Horizontal

transmission is the major route to spread organisms. Vertical transmission of

campylobacter rarely occurs since only a few bacteria could survive on eggs. In contrast

to Salmonella, Campylobacter cannot survive under long dry conditions of feeding food,









so the food is not the source for transmission of Campylobacter (Mead, 2004). Bacteria

counts on carcasses are likely to increase during defeathering and evisceration (Nather

et al., 2009).

Campylobacter are gram-negative, very slender curved to spiral shaped rods, 0.2-

0.4 pm in width and length is 1.5-3.5 pm. Most Campylobacter are motile by a single

flagellum. Campylobacter can survive well at microaerophilic conditions. The

atmosphere that contains 5% oxygen and 10% carbon dioxide is optimum growth for

Campylobacter (Cunningham and Cox, 1987; Simmons et al., 2008). Keener et al.

(2004) stated that Campylobacterjejuni is unusually sensitive to oxygen and

dehydration. Jay (1992) also stressed that Campylobacter requires low oxygen,

approximately 6% to 8% to grow, and if oxygen is more than 21%, the growth of

Campylobacterjejuni is inhibited. Campylobacter has a higher optimum growth

temperature than Salmonellae (Mead, 2004). Studies reported that when the internal

temperature of ground beef reached 70C, Campylobacter counts were reduced 7 log

cfu/g, when tested after 10 minutes. When placing chicken carcass into -18 C storage

condition, Campylobacter counts were reduced by 5 log cfu/g (Jay, 1992).

Antimicrobials Used in Chicken Breast Meat to Control Pathogenic and Spoilage
Bacteria

ICMSF (1998) listed three mechanisms that could contribute to attachment of

bacterial regarding poultry carcasses surface, there are retention, entrapment and

adhesion mechanisms. "Retention" occurs when poultry carcasses contact the

contaminated water. The bacteria coming from the contaminated water is residual and

develops film on the surface of carcasses. Therefore, the microbial load on the surface

of carcasses has positive effect with bacteria in the water. "Entrapment" occurs when









the muscle tissues are swollen by absorbed water, followed by bacterial penetration into

the deep channel or crevices from the outer poultry carcass surface. This processing

occurs easily in broken skin, meat and cut meat, such as chicken breast meat. Also as

time increased, bacteria retained on the surface of carcass, might change to entrapped

situation. Under the circumstances, spraying carcass with water cannot remove

contaminants. Antimicrobials are added into spraying water and remove these

entrapped bacteria. "Adhesion" occurs in the soft tissue and loosed connective tissue,

but not all bacteria are capable of adhesion to these tissues. Adhesion bacteria function

when the optimal conditions such as neutral pH, low ionic strength, and immersion in

water for some time occur. When adhesion occurs, spraying, rinsing, and immersion are

not good methods to reduce microbial load. Researchers reported that adding salts into

immersion water could decrease the degree of adhesion and increase ionic strength.

The effectiveness of chemical compounds depends on bacteria retained, entrapped or

adhered to the tissue.

Fresh broiler chicken meat is prone to microbiological spoilage due to providing

excellent substrate for microbial growth. If fresh meat is stored under inappropriate

conditions or is not treated with preservatives, it becomes very perishable (Mead, 2004).

The purpose of chemical intervention strategies in chicken carcasses is to prevent

contaminants, remove contaminants, and extend lag phase of pathogenic and spoilage

organisms, or destroy contaminants completely (George, 1989). Many Intervention

decontaminants are described and grouped into physical, chemical and combination

chemical and physical methods. Physical methods include rinsing, spraying, steaming

with hot or cold water, Ultra high pressure, irradiation, Pulsed Electric Field, Ultrasonic









energy, and UV light. Chemical approaches include but not limited to chlorine (chlorine

dioxide, cetylpyridinium chloride, sodium hypochlorite, stannous chloride, timsen,

acidified sodium chlorite, sodium chlorite), organic acids (lactic acid, acetic acid, citric

acid, propionic acid) and organic acid salt preservatives (sodium lactate, sodium

sorbate, sodium citrate, potassium lactate; inorganic phosphates (trisodium phosphate,

sodium tripolyphosphate, acid sodium pyrophosphate); bacteriocins (nisin, magainin;

EDTA-nisin); oxidizers (hydrogen peroxide, ozone, quaternary ammonium) and other

chemical compounds such as sodium metasilicate (Dicken and Whittemore, 1997;

Kristen et al., 1997; Bolder, 1997; Bilgili et al., 1998; Russell, 1998; Russell, 2000; Aktas

and Kaya, 2001; Jimenez-Villarreal et al., 2003; Northcutt et al., 2005; Ricke et al.,

2005; Economou et al., 2009; Quilo et al., 2009). In this literature review, the

effectiveness of these chemical compounds in poultry processing plants and their

mechanisms of action will be described in detail.

The suitable chemical agents should have effective ability with low concentration,

fast working, without residual on the surface of the carcass, and no detrimental effect to

consumers. The agents should not produce undesirable appearance, texture, color,

odor and favor. Some of the chemical compounds listed above are suited for one

process, but might fail in another. Some chemical compounds have been verified to

control microbial growth on lab level but can fail when applied under commercial plant

conditions. For example, the problems could be meat color change, off-flavor

development, equipment and tools erosive. In this literature review, the advantages or

disadvantages of these interventions and their chemical actions and mode action will be

explained.









Chloride

European Food Safety Authority (EFSA, 2005) reported antimicrobials that can be

used in poultry carcasses include sodium tripolyphosphate, acidified sodium chlorite,

chlorine dioxide, and peroxyacetic acid. In the United States, Chlorinated water was

employed for carcass washing, spraying carcass or equipment and chiller water for on-

line reprocessing to reduce microbial growth and cross-contamination (EFSA, 2005;

Northcutt et al, 2005). Chlorine solution prohibited the Salmonella growth in water, but

failed to reduce the bacteria on the surface of carcasses (Brotsky and Bender, 1991).

The most common antimicrobial product used in carcass spraying is acidified sodium

chlorite (Bauermeister et al., 2008). However, in chiller processing, chlorine dioxide is

being used instead of acidified sodium chlorite because of stability of chlorine dioxide;

however, the effectiveness of chlorine dioxide is influenced by the organic matters from

water and chicken. Chlorine and organic matter could react and produce

trihalomethane, a mutagenic compound. The compound might cause cancer (Cooper,

2009). Recently, researchers pointed out that chlorine solutions could react with organic

matter from high protein food such as chicken breast meat and produce semicarbazide

(EFSA, 2005). In the light of the limited evaluation information, whether the compounds

could threaten public health still needs further researches. Pearson and Dutson (1994)

reported that chlorine or acid spaying could corrode equipment and tools when used to

spray the poultry carcass. Bauermeister et al. (2008) also reported that chlorine

significantly lost its efficacy when the water contained high amount of organic matter

and pH over 7.0.

Acidified sodium chlorite (ASC) is FDA (U.S. Food and Drug Administration) and

USDA approved for use as an antimicrobial intervention on post-evisceration poultry









products. ASC is the formation of sodium chloride with any acid that is generally

recognized to be safe in food. The chemical formula of ASC is NaCIO2. The pH range is

2.3 to 2.9 at concentration of 500-1200 mg/L sodium chloride dip. This solution can be

applied either as a 15 second spraying or a 5-8 second. This treatment could result in 2

log reductions in Escherichia coli, Campylobacter spp., and Salmonella spp. For

immersion chilled water, the concentration increases to 150 mg/L at a pH between 2.8

and 3.2 (EFSA, 2005). ASC provides an average 2.28 log reductions in E. coli and 2.56

log reductions in Campylobacterspp. The antimicrobial properties come from chlorous

acid, which has stronger oxidation than either chlorine dioxide or chlorine. Chlorous acid

oxidizes cellular constituents and disrupts protein synthesis (EFSA, 2005).

Organic Acids and Their Salts

Various organic acids could prohibit gram-negative spoilage microbial growth

attaching on surface of meat (Bolder, 1997). They could effectively reduce the microbial

load in the scalding water but have no significantly effect on the carcasses (Dickens and

Whittemore, 1997). Two common organic acids, acetic acid and lactic acid, have been

investigated for possible utilization in the meat and poultry industry. This is because

they are effective for reducing specific organisms and are generally recognized as safe

(GRAS) (Pearson and Dutson, 1998). The organic acid treatment may impact meat

color and flavor which are determined by the concentration and application of acid.

Aktas and Kaya (2001) reported that concentration of lactic and citric acid over 1.0%

could cause meat sourness. Bauermeister et al. (2008) reported that organic acids,

including acetic, formic, citric, and lactic and propionic acid, could control microbial

proliferation but could also bring about an undesirable flavor and color. He also pointed

out that 0.022% peracetic acid and 0.012 % hydrogen peroxide in solution could









maintain or increase the acceptability of flavor and color in poultry, in addition to its

antimicrobial function. He drew the conclusion that low levels of propionic acid

employed as antimicrobial in poultry chillers could reduce the population of Salmonella

Typhimurium and Campylobacterjejuni on the final product without a change in

organoleptic characteristics.

Bilgili et al. (1998) reported that organic acid (acetic, citric, lactic, malic, mandelic

and tartaric acid) stimulated chiller condition, decreased lightness and increased

yellowness values, as levels of concentration increased. In addition, lactic acid with

sodium benzoate could control proliferation of Salmonella on chicken skin when

refrigerated. A combination of 1% lactic acid and 0.5% hydrogen peroxide has 4 log

reductions of Salmonella. Bauermeister et al. (2008) indicated that when carcasses

inoculated with Salmonella (106 cfu) or Campylobacter (106 cfu), peracetic acid at

concentration as low as 0.0025% was effective in reducing Salmonella spp. and at

concentration as low as 0.002% was effective in reducing Campylobacter spp., when

placed into poultry chiller. They also reported that the combination of 1% acetic acid and

3% hydrogen peroxide could significantly decrease the load of Escherichia coli,

Salmonella, and Listeria innocua when sprayed on a previously inoculated beef

carcass. Russell (1998) reported that 5% or more lactic acid eradicated all spoilage

organisms isolated from broiler chicken. Bolder (1997) reported that poultry carcasses

treated with 1-2% lactic acid solution after slaughter and during storage reduced

bacteria population without a change in color or flavor. Brotsky and bender (1991)

reported that using lactic or acetic acid above the specified level would control bacteria

but was unacceptable with regards to sensory change. Organic acid antimicrobial









efficacy is determined by the level of acid and the pH value of the solution. Lactic acid

removed bacteria attached to lean pork faster than bacteria attached to fatty parts. A

combination of lactic acid and sodium benzoate could extend the shelf life and maintain

meat quality. Therefore, organic acids, especially lactic acid, have the potential to be

promising meat and poultry surface decontaminants.

The addition of organic acid and their salt compounds as preservatives in poultry

and meat products has been utilized in commercial meat plants (Alvarado and Mckee,

2007). These chemical antimicrobials include sodium lactate, potassium lactate,

sodium citrate, and combinations of these compounds. Jimenez-Villarreal et al. (2003)

determined that cetylepyridinium chloride, chlorine dioxide, lactic acid and trisodium

phosphate could be effective in reducing the numbers of bacteria. Also, cetylepyridinium

chloride and trisodium phosphate could maintain the meat color and improve sensory

characteristics and decrease the lipid oxidation rate compared to the untreated ground

beef. Researchers also concluded that potassium lactate could be effective in reducing

Listeria monocytogenes on various meats. Previous studies pointed out that sodium

lactate, sodium acetate, sodium diacetate, potassium lactate, sodium citrate, the

combination of sodium lactate and sodium diacetate, and the combination of sodium

lactate and potassium were able to prevent the microbial population and increase the

sensory evaluation of meat product (Shafit, 2000; White, 2000; Alvarado and Mckee,

2007). Shafit (2000) reported that 1.25 % lactic acid could lead to the discoloration of

meat, and concentration of more than 2.0 % could cause flavor problems. Sodium

lactate also has these problems. Williams and Phillips (1998) determined that increasing

the concentration of sodium lactate reduced the population of psychrotrophic counts on









chicken breast meat. However, over 2% of sodium lactates could result in the cooked

chicken meat having a bitter taste, so sensory problems limit the concentration level of

chemicals use (Williams and Phillips, 1998). The effect of salt of organic acid has been

attributed to cross molecular membranes and acid crosses the membrane barrier to

acidify the cell interior.

Sodium Tripolyphosphate

The most commonly used poultry marinade is sodium tripolyphosphate, which had

been shown to increase meat yield and water-holding capacity, as well as improve color

and texture. Phosphate salt could prevent bacterial growth on carcass skin and not

influence color or texture. Sodium tripolyphosphate as an intervention strategy could

control the growth of Salmonella, Campylobacter and E. coli 0157:H7 (Weber et al.,

2004).

The chemical mode of action of sodium tripolyphosphate differs from chlorine,

ozone, chlorine dioxide and acidified sodium chlorite, which could react and quickly

remove unsaturated bonds from solution, and reduce the antimicrobial effect. Sodium

tripolyphosphate is an alkaline salt. The high pH value of sodium tripolyphosphate (pH

12.1) could destroy cell membrane and damage the fat film of meat. The hydroxyl

radical, remaining on meat surface, continues to function as an antimicrobial and retard

the growth of bacterial after treatment (Ricke et al., 2005). It can be applied to remove

"retention" and "entrapment" microorganisms. Brotsky and Bender (1991) reported that

the death rate of Salmonella increased during scalding if the pH value of scald warm

water was adjusted to around pH 9.0. The pH adjusting agents were sodium hydroxide,

potassium hydroxide, sodium carbonate, and alkaline tripolyphosphate. He also

concluded that trisodium phosphate dodecahydrate had the most powerful lytic action to









Salmonella typhosa, compared with monosodium disodium, and dipotassium

orthophosphate. In addition, treating poultry carcasses or parts with 4% to 12%

trisodium or tripotassium phosphate dodecahydrate was equally effective as sodium

hydroxide, or phosphoric acid and sodium hydroxide. Alvarado and McKee (2007)

mentioned that acid pH phosphates will lower water holding capacity, while alkaline

phosphates had the reverse trend, which means that meat samples had a higher

cooking yield, higher water-holding capacity, more juicer and tender, longer shelf life,

higher color stable capacity, lower purge lost, and lower oxidation acidity after treated

with alkaline phosphate.

Sodium Metasilicate

Sodium metasilicate (SMS) share some common with sodium tripolyphosphate. It

is an alkaline salt with a high pH the ability to buffer. The pH value of a 1% aqueous

solution is about 12.3, and the pH value of 5% aqueous solution is approximate 12.7.

Sodium metasilicate has strong corrosive and penetrating ability. When sodium

metasilicate reacted with protein and collagen, the saponifying effect occurs on lipid and

dehydrates the tissue and cells. It can maintain pH stability when reacted with muscle

tissue (Temple and Smith, 1997).

Sodium metasilicate as antimicrobial has been of interest in for years. Sodium

metasilicate is considered GRAS (Generally Recognized as Safe) under 21 CFR173.310

and is permitted to be added directly to food for human consumption (FDA, Code

Federal Register, 2006). The USDA approved the application of sodium metasilicate on

raw beef carcasses as an anti-microbial processing aid (USDA, 2009). Up to 4% (plus

or minus 2%) of a solution could be used in the raw beef carcasses.









Quilo et al. (2009) applied the 4% SMS (w/v) to beef trimming and observed that

the SMS treated sample was much juicier, had lower shear force, had less cooking loss

than the control, and had no difference in sensory characteristics compared to the

control product. Bender (2006) reported that the protein containing products contacted

with alkali silicate solution for a period of time could sufficient to saturate the food

products and absorbed the solution into product. He also concluded that SMS had lower

cooked loss than untreated samples. Additionally, sodium metasilicate at concentration

of 0.35% had slightly higher cooking yield than 0.35% phosphate treated samples.

Weber et al. (2004) indicated that exposure of E. coli 0157:H7 to 0.4% SMS solution for

20 minutes had same effective with exposure to 0.6% SMS solution for 5-10 seconds

which caused 100% inhibition without recoverable.

Recently, USDA approved sodium metasilicate for injection into raw meat and

poultry as a 2% marinade solution by weight (UDSA, 2009). However, there is no

documentation of the affect of sodium metasilicate in poultry products and little

documentation recording the mechanisms of using sodium metasilicate to inhibit the

growth of microorganisms. Therefore, SMS may have the same effectiveness in control

growth of Salmonella and Campylobacter and may have the same mechanical action as

sodium tripolyphosphate. Moreover, it may also improve the physical and chemical

properties without sensory undesirable detectable. Also it may have no side effect to

environment residue which may be different with sodium tripolyphosphate. Also it may

also be more effective at extending shelf life when combined with other technologies.









CHAPTER 3
MATERIALS AND METHODS

This study was conducted in three phases. Phase I included preliminary studies to

determine application method and to evaluate the effectiveness of sodium metasilicate

(SMS) at the USDA approved level for poultry meat. Phase II included preliminary

studies to determine the effectiveness of sodium metasilicate at approved and elevated

levels and a shelf life study. Phase III included to investigate the effectiveness of

sodium metasilicate at the USDA approved level and elevated levels on antimicrobial,

sensory, chemical and physical characteristics of fresh chicken breast meat and a shelf

life study. Marination processing was conducted at the University of Florida Meat

Processing facility, and all analyses were performed in the Meat Research Laboratories.

Phase I. Preliminary Study: Application Method and Evaluation of Sodium
Metasilicate at Approved Level for Poultry Meat

Sample Preparation

USDA GRADE A 97% fat free boneless skinless chicken breast fillets with rib meat

and with expiration date of at least 7 days were purchased from a local supermarket. In

order to insure the freshest fillets were used in the study, the fillets were purchased on

the day of arrival to the store and immediately transported to the Meat Research

Laboratory, and stored at 4C in a walk-in cooler.

Sample Treatment and Marination Yield

Experiment one

Experiment one was conducted in a 4C walk-in cooler. The fillets were randomly

and evenly divided into three groups. A still-marinating process was used wherein the

fillets were weighed and immersed into solutions containing either 0, 1 or 2% sodium

metasilicate (AVGARDXR, Lot. U012106, Danisco USA Inc., New century, KS) for 30









minutes (15 minutes for each side). The treated fillets were drained for 2 minutes,

weighed and two fillets were packaged in a Cryovac 2.0" tray (Type CS978, Mulinix

package Inc., Fort Wayne, IN), overwrapped with 18"X2000'plastic foodservice film

(CompanionsTM, Unipro Foodservice Inc., Atlanta, GA) and stored at 40C for analysis.

All samples were analyzed for marination yield, pH, total psychrotrophic counts, cooking

yield, color, shear force and sensory evaluation on day 0.

Experiment two

Experiment two was conducted in the Meat Processing facility under simulated

plant conditions in a 20C processing room. Eighteen fillets were randomly and evenly

divided into three groups. The fillets were weighed and placed into a vacuum tumbler

(Lyco vacuum tumbler, model 40, Columbus, WI) with marinade solutions containing

either 0, 1 or 2% sodium metasilicate solutions and tumbled under vacuum for 20

minutes at approximate 172.32 kPa (kilopascal) of pressure. The objective was to use

the marinade solution to yield 10% increase in the total fillet original batch weight for

each treatment. A vacuum tumbling processing was performed in a 20C cold room to

prevent fillets from increasing in temperature during marination. Control treatment

samples were marinated with tap water (20C). For 1% and 2% treatments, the sodium

metasilicate compound was completely dissolved in tap water before marinated with

samples. Except for tap water and sodium metasilicate, no other ingredients were

added to the fillets in this study. The treated fillets were weighed and packaged in trays

as previously discussed. Two fillets were placed into each tray and stored at 40C for 6

days. For each treatment, two packages were randomly collected on 0, 1, 3 and 6 days

and analyzed for marination yield, pH, total psychrotrophic counts, cooking yield color,









Instron and sensory evaluation. The marination yield (%) was calculated using the

following equation:

Marination Yield (%) =100* W1/W2 (3-1)

W2 represents weight of fillets pre-marination, g

W1 represents weight of fillets post-marination, g

pH Analysis

The pH analysis was the same for experiments one and two. The pH value was

determined immediately after completing microbiology analysis. The pH value was

measured using a pH Meter (Accumet Basic AB15, Fisher Scientific, Fair Lawn, NJ).

Prior to analysis of pH for each treatment, the pH meter was calibrated using pH buffers

4.00 (SB101-500, Fisher Scientific, Fair Lawn, NJ) and 7.00 (SB 107-500, Fisher

Scientific, Fair Lawn, NJ). The probe was placed into the sample homogenate and

allowed to equilibrate for one minute before the pH reading was recorded. All pH

readings were performed in duplicates.

Cooking Yield Analyses

Experiment one: Grill reconstitution method

The grills (Hamilton beach, proctor-silex, Inc., Southern Pines, NC) were heated to

176.7 C approximately 15 minutes. The fillets from the same treatment were placed on

the same grill, and were heated for approximately 30 to 40 minutes. The fillets were turn

over when the grill line occurred on the surface during grilling. The copper-constantan

thermocouples were inserted the thickest part of fillets before grilling. The fillets were

stopped cooking when the internal temperature reached 74 C monitored with

thermocouples attached to a potentiometer. The weights (Mettler Toledo scales, Mettler









instrumental corp., Model: MS 3001S 103, Hightstown. NJ) of before and after cooked

fillets were recorded and cooking yield (%) was calculated using the following equation:

Cooking yield % = 100* W2/W1 (3-2)

W1 represents the weight before grilling, g

W2 represents the weight after grilling, g

Experiment two: Oven reconstitution method

Four fillets of each treatment were placed in a roasting pan. The roasting pan was

covered with aluminum foil (Handi-Foil; 18"x 500', Wheeling, IL,) to avoid moisture lost

from fillets. The fillets were baked in a conventional gas oven (Model: JGRS14 GE Built

In Gas Oven) at 176.7 C, until internal temperature reached 74 C which was

monitored with copper-constantan thermocouples attached to a potentiometer. The

copper-constantan thermocouples were inserted into the thickest part of the fillets

before baking. The oven was preheated approximately 20 minutes until the oven

temperature reached 176.7 C. The weights (Mettler Toledo scales, Mettler instrumental

corp., Model: MS 3001S 103, Hightstown. NJ) of the fillets were recorded before and

after cooking, and cooking yield (%) was calculated using the following equation:

Cooking yield % = 100* W2/W1 (3-3)

W1 represents the weight before cooking, g

W2 represents the weight after cooking, g

Microbiological Analyses

Experiment one

The treated fillets were analyzed for total psychrotrophic counts on each assigned

sampling days. Twenty-five gram fillets were aseptically cut and placed into a sterile

stomacher bag (400ml, Fisher Scientific, Pittsburgh, PA). The 225 ml sterile 0.1%









peptone water (Cat. No. DFO1897-17-4, Detroit, MI) was poured into the stomacher

bag. The stomacher bag was manually massaged for two minutes to loose surface

bacteria. One milliliter of homogenate aliquot from stomacher bag was transferred into a

test tube, which containing 9 ml sterile 0.1% peptone water. Two tubes were employed

for each treatment from 10-1 to 10-2 serial dilution. The contents of tubes were mixed

using vortex (Votex Geniz 2TM Cat. No. 12-812 Model G 250, Fisher scientific, McGaw,

IL) for 15 seconds to insure the bacterial evenly distributed. 3M Petrifilm Aerobic count

plate (Cat. No. 6406, Fisher Scientific, Pittsburgh, PA) was placed on a level surface.

The top film was lifted, and 1 milliliter aliquot from each tube was ascetically transferred

into the plate, and a plastics squared spread was placed on the top center of plate and

dispersed the aliquot on plate. The 3M Petrifilm Aerobic Plate Count was held at room

temperature forl5 minutes. Plates were incubated at 70C refrigerator for 48 hours in a

horizontal position for the total psychrotrophic count (Hamm, 2001). Microbiological

counts were expressed as Logarithmic Colony Forming Units per grams (log cfu/g). The

counts were recorded when containing 25-250 colonies on plate. All samples were

plated in duplicates.

Experiment two

The sample homogenate and serial dilutions were prepared as discussed in

Experiment One. Approximately 0.1 mL aliquot of the diluted sample homogenate from

each serial dilution was aseptically transferred into sterile disposable 100 x 20mm Petri

plates (Cat. No. 08-757-103C, Fisher Scientific, Suwanee, GA) that contained

prepoured hardened Tryptic Soy Agar (No.1010617, MP Biomedicals, Inc., Solon, OH).

The homogenate was spreaded on the plates using a sterile glass hockey stick. The

stick was sterilized with 70% ethanol and flamed before spreading. The plates were









incubated aerobically at 70C for 10 days to determine the total psychrotrophic counts

(Hamm, 2001). Microbiological counts were expressed as Logarithmic Colony Forming

Units per grams (log cfu/g). The counts were recorded when 25-250 colonies were on

the plate. All plates were done in duplicates.

Objective Color Measurement

The color of raw and cooked fillets was measured with the Hunter MiniScan XE

plus colorimeter (Hunter Associates Laboratory, Inc, Reston, VA) in the same manner

for experiments one and two. The colorimeter was calibrated with a standard black tile

and white tile as recommended by manufacturer. Fillets (two fillets per package) were

measured at a total of four different locations for L*, a* and b* values. The instrumental

color of L* a* b color spectrum were recorded, where L* represents the total light

reflected on a scale ranging from 0 = black to 100 = white, a* represents the amount of

red (positive values) and green (negative values), and b value represents the amount

of yellow (positive values) and blue (negative values).

Warner-Bratzler Shear Force Analysis

The 1.0 cm cooked strips were employed for shear force measurement. The

cooked 1.0 cm strips were covered with aluminum foil and stored at 40C for 18 hours

prior to shear force measurements. Texture measurements were conducted as

described by Lyon and Lyon (1991). Each strip was oriented in the Warner-Bratzler

shear attachment, which was attached to the Model 1011 Instron Texture machine

(Model 1011 Instron, Instron Corporation, Norwood, MH). The speed of cross-head was

200 mm/min with a 50 kg load cell. The full scale range was 10 kg (Williams and

Phillips, 1998). The Warner-Bratzler shear force values were recorded in kilograms.

Five values were obtained from each treatment. All treatments were done in duplicates.









Sensory Evaluation Analyses

Experiment one: Grilled fillets

The fillets were cut into two 1.9 cm wide strips paralleled with the direction of the

fibers. One strip was separated into three or four cubic cm for sensory evaluation, and

another strip was used to determine instrumental texture. The cubes were trimmed into

uniform size. Two cubes of each treatment were placed into a pre-warmed container to

keep the serving temperature at approximate 55C. The serving containers were

labeled with one digit numbers. The sensory evaluation was performed in the Meat

Laboratory sensory room equipped with eleven separated booths. Each booth was

equipped with a ceiling lighting system with red, white, blue, or yellow lighting as

needed (Williams and Phillips, 1998). The eight-point hedonic scoring scales were

employed for Juiciness, chicken flavor intensity, overall tenderness and a six-point

hedonic scoring scale was employed for off-flavor. The samples were evaluated in an

informal taste test by two experienced panelists.

Experiment two: Baked fillets

The panelists were recruited from faculty, undergraduate and graduate students

and staff in the Department of Animal Sciences who had participated in previous poultry

sensory evaluations. The panelists were trained to comprehend the conception of

Juiciness, tenderness, and chicken flavor intensity and to describe off-flavor. Juiciness

evaluation included two treatments. Samples were baked in a conventional gas oven

and covered with aluminum film to retain maximum moisture, and another group of

samples were grilled to produce samples with lower moisture content than the baked

samples. Tenderness evaluation included two treatments of chicken tenderloin. One

group of samples were baked in a conventional gas oven and covered with aluminum









film to retain maximum moisture, and another group of samples were grilled, allowed to

cool at 4C for 15 minutes, and reheated in the microwave (Microwave Oven, Model:

NN-S961, Panasonic, San Francisco, CA) for 3 minutes to produce a tough texture.

Chicken flavor intensity evaluation included using different marinade solution and time.

One treatment was soaked into chicken broth overnight, the weight of chicken broth

marinade accounted for 30% total weight of fillets, this treatment had stronger chicken

flavor. Another treatment was marinated with tap water and employed still-marinated for

30 minutes, the amount of tap water was 10% of fillets weight, and baked the samples

at 176.7 C. The marination processing was performed at 4C cooler. Off-flavor

evaluation included four treatments. Panelists were trained to identify the off-flavor

descriptors, such as salty, metallic, and bitter. The samples were marinated with tap

water, 2% sodium chloride (salty), 2% of potassium chloride (bitter) and 0.5% sodium

tripolyphosphate (metallic), and then baked in a conventional oven at 176.7C, until

internal temperature reach 74C. The panelists were also trained to fill in the sensory

sheet.

The eight-point hedonic scoring scales were employed for juiciness, chicken flavor

intensity, and tenderness evaluation, where 8 represents extremely juicy, extremely

intense and extremely tender, 7 represents very juicy, very intense, and very tender, 6

represents moderately juicy, moderately intense, and moderately tender, 5 represents

slightly juicy, slight intense and slight tender, 4 represents slightly dry, slight bland and

slight tough, 3 represents moderately dry, moderately bland and moderately tough, 2

represents very dry, very bland and very tough, and 1 represents extremely dry,

extremely bland and extremely tough. A six-point scale was utilized for off-flavor









evaluation. 6 represents none detected, 5 represents threshold; barely detected, 4

represents slight off-flavor, 3 represents moderate off-flavor, 2 represents strong off-

flavor and 1 represents extreme off-flavor.

Cooked meat was sectioned for sensory and instrumental texture measurements

as described by Lyon et al. (2005) with some minor changes. The fillets were cut into 2

to 3 cubic cm wide strips paralleled with the direction of fiber. On strip was employed for

instrumental texture, and another strips were employed for sensory evaluation. The

cubes were discarded when the fibers from strips were not paralleled. The cubes were

trimmed into uniform sizes. Two cubes of each treatment were placed into a pre-

warmed container to keep the serving temperature at approximate 550C. The serving

container was labeled with one digit number. All treatments for sensory evaluation were

served at the same time.

Phase II. Preliminary Study: Determination of the Effectiveness of Sodium
Metasilicate at Approved and Elevated Levels and a Shelf Life Study.

In phase II, the sampling days included 0, 1, 3, 5, 7, 9 days. The fillets were

marinated with tap water that contains 1, 2, 3 or 4% sodium metasilicate. The materials

and methods for sampling preparation, sampling treatment, marination yield, pH

analysis, microbiology analysis, color, cooking yield and sensory evaluation were the

same as phase I in experiment two.

This preliminary study not only determined the effectiveness of the USDA

approved levels, but also evaluated the effectiveness of elevated levels of sodium

metasilicate on the shelf life of poultry meat. In addition to the parameters determined in

experiment II in phase I, water-holding capacity values were determined.









Water-Holding Capacity Analyses

Water-holding capacity with sodium chloride. The water-holding capacity

method described by zhuang et al. (2008) was conducted in this study. The treated

fillets were minced with food processor (Braun Multiquick Hand Blender, Model: MR 400

HC, Type 4185, Lighthouse Point, FL). Ten gram minced samples were placed into a 50

ml tube containing 15 ml of 0.6 M sodium chlorine solution and vortexed (Votex Geniz

2TM Cat. No. 12-812 Model G 250, Fisher scientific, McGaw, IL) for 1 minute per tube to

ensure evenly distribution. The tubes were placed in a 4C cooler for 15 minutes prior to

centrifuge. The centrifuge machine (Superspeed Refrigerated Centrifuge, Sorvall RC-

5B, Beverly, MA) was turned on approximate one hour before measuring. The tubes

were centrifuged at 3000 rpm at 40C for 15 minutes. The liquid was decanted, and the

solid material was maintained in the tube. The weights of before and after centrifuged

meat were recorded.

Water-holding capacity with distilled water. The water holding capacity

percentage values also were determined by distilled water method. The purpose of

measuring these values with distilled water were to compare with fillets measured with

sodium chloride. Except for addition of distilled water, the procedure to determine water-

holding capacity was the same as using sodium chloride. Therefore, the 15 ml distilled

water in place of sodium chloride was added into tubes that contained ten grams

minced samples. The samples were analyzed in duplicate. The data for this method

were collected through day 3 to day 9. The same equation was used for these two

methods.

WHC (%) was determined by using the following equation:

WHC % = 100 (W1-W2)/W3 (3-4)









Where W1 represents solution added into the sample, g

W2 represents solution removed, g

W3 represents the meat sample mass, g

Phase III. Investigation of the Effectiveness of Sodium Metasilicate at the USDA
Approved Level and Elevated Level on Antimicrobial, Sensory, Chemical and
Physical Characteristics of Fresh Chicken Breast Meat Stored at 40C for 9 Days

In phase II test, the sampling days included day 0, 1, 3, 5, 7 and 9, and in phase

III, the sampling days included days 0, 1, 3, 5, 6, 7, and 9, and purge loss was

measured. The procedures of sampling preparation, sampling treatment, marination

process, pH measurement, microbiology analysis, and water holding capacity were the

same as phase II tests. The parameters of sensory evaluation, raw meat color, cooked

meat color, cooking yield, Warner-Bratzler shear force were performed in duplicates in

phase III. The treatments included 0 (control), 1, 2, 3, and 4% sodium metasilicate in

marinade solution.

Sample Preparation

USDA GRADE A 97% fat free boneless skinless chicken breast fillets with rib meat

and with expiration date of at least 7 days were purchased from a local supermarket. In

order to insure the freshest fillets were used in the study, the fillets were purchased on

the day of arrival to the store and immediately transported to the Meat Research

Laboratory, and stored at 4C in a walk-in cooler.

Sample Treatment and Marination Yield

Experiment was conducted in the Meat Processing facility under simulated plant

conditions in a 2C processing room. One hundred forty fillets were randomly and

evenly divided into five groups. The fillets were weighed and placed into a vacuum

tumbler (Lyco vacuum tumbler, model 40, Columbus, WI) with marinade solutions









containing either 0, 1, 2, 3 or 4% sodium metasilicate solutions and tumbled under

vacuum for 20 minutes at approximate 172.32 kPa of pressure. The objective was to

use the marinade solution to yield 10% increase in the total fillet original batch weight

for each treatment. Vacuum tumbling processing was performed in a 2C cold room to

prevent fillets from increasing in temperature during marination. Control treatment

samples were marinated with tap water (2C). For sodium metasilicate treatments, the

sodium metasilicate compound was completely dissolved in tap water before marinated

with samples. Except for tap water and sodium metasilicate, no other ingredients were

added to the fillets in this study. The treated fillets were weighed and packaged in

Cryovac 2.0" trays (Type CS978, Mulinix package Inc., Fort Wayne, IN). Two fillets were

placed into each tray and stored at 4C for 9 days. For each treatment, two packages

were randomly collected on 0, 1, 3, 5, 6, 7 and 9 days and the samples were analyzed

the marination yield, pH, the total psychrotrophic counts, water holding capacity, purge

loss, cooking yield, color, shear force and sensory evaluation. The marination yield (%)

was calculated using the following equation:

Marination Yield (%) =100* W1/W2 (3-5)

W2 represents weight of fillets pre-marination, g

W1 represents weight of fillets post-marination, g

pH Analysis

The pH value was determined immediately after completing microbiology analysis.

pH value was measured using pH Meter (Accumet Basic AB15 pH Meter, Model no. SA

520, Fisher Scientific, Fair Lawn, NJ). Prior to analysis of pH for each treatment, the pH

meter was calibrated using pH buffers 4.00 (SB101-500, Fisher Scientific, Fair Lawn,

NJ) and 7.00 (SB 107-500, Fisher Scientific, Fair Lawn, NJ). The probe was placed into









the sample homogenate and allowed to equilibrate for one minute before the pH reading

was recorded. All pH readings were performed in duplicates.

Water-Holding Capacity Analyses

Water-holding capacity with sodium chloride. The water-holding capacity

method described by zhuang et al. (2008) was conducted in this study. The treated

fillets were minced with a food processor (Braun Multiquick Hand Blender, Model:

Mr400 HC, Type 4185, Lighthouse Point, FL). Ten gram minced samples were placed

into a 50 ml tube containing 15 ml 0.6 M sodium chlorine solution and vortexed (Votex

Geniz 2TM Cat. No. 12-812 Model G 250, Fisher scientific, McGaw, IL) for 1 minute per

tube to insure even distribution. The tubes were placed in a 4C cooler for 15 minutes

prior to centrifuge. The centrifuge machine (Superspeed Refrigerated Centrifuge,

Sorvall RC-5B, Beverly, MA) was turned on approximate one hour before measuring.

The tubes were centrifuged at 3000 rpm at 40C for 15 minutes. The liquid was

decanted, and the solid material was maintained in the tube. The weights of before and

after centrifuged meat were recorded (Zhuang et al., 2008). The samples were analyzed

in duplicate.

WHC (%) was determined by using the following equation:

WHC % = 100 (W1-W2)/W3 (3-6)

Where W1 represents solution added into the sample, g

W2 represents solution removed after, g

W3 represents the meat sample mass, g

Water-holding capacity with distilled water. Except for addition of distilled

water, the method was the same as described by zhuang et al. (2008). The treated

fillets were minced with a food processor (Braun Multiquick Hand Blender, Model:









Mr400 HC, Type 4185, Lighthouse Point, FL). Ten gram minced samples were placed

into a 50 ml tube containing 15 ml distilled water and vortexted (Votex Geniz 2TM Cat.

No. 12-812 Model G 250, Fisher scientific, McGaw, IL) for 1 minute per tube to insure

even distribution. The tubes were placed in a 40C cooler for 15 minutes prior to

centrifuge. The centrifuge machine (Superspeed Refrigerated Centrifuge, Sorvall RC-

5B, Beverly, MA) was turned on approximate one hour before measuring. The tubes

were centrifuged at 3000 rpm at 40C for 15 minutes. The liquid was decanted, and the

solid material was maintained in the tube. The weights of before and after centrifuged

meat were recorded. The samples were analyzed in duplicate.

WHC (%) was determined by using the following equation:

WHC % = 100 (W1-W2)/W3 (3-7)

Where W1 represents solution added into the sample, g

W2 represents solution removed after, g

W3 represents the meat sample mass, g

Purge Loss Analysis

Purge loss included any liquid that was collected from the package tray. The

weights (Mettler Toledo scales, Model: MS 3001S 103, Switzerland) of liquid released

from fillets were recorded. Purge loss (%) was calculated by using the following

equation:

Purge loss (%) =100*W1/W2 (3-8)

W1 represents liquid released from fillets, g

W2 represents original fillet weight, g









Cooking Yield Analysis

Four fillets of each treatment were placed in a roasting pan. The roasting pan was

covered with aluminum foil (Handi-Foil; 18"x 500', Wheeling, IL) to avoid moisture lost

from fillets. The fillets were baked in a conventional gas oven (Model: JGRS14 GE Built

In Gas Oven) at 176.70C until internal temperature reached 740C, which was monitored

with copper-constantan thermocouples attached to a potentiometer. The copper-

constantan thermocouples were inserted into the thickest part of the fillets before

baking. The oven was preheated approximately 20 minutes until the oven temperature

reached 176.70C. The weights (Mettler Toledo scales, Model: MS 3001S 103,

Switzerland) of the fillets were recorded before and after cooking, and cooking yield (%)

was calculated using the following equation:

Cooking yield % = 100* W2/W1 (3-9)

W1 represents the weight before cooking, g

W2 represents the weight after cooking, g

Microbiological Analysis

The treated fillets were analyzed for total psychrotrophic counts on each of the

assigned sampling days. Twenty-five gram fillets were aseptically cut and placed into a

sterile stomacher bag ( Cat. NO. 400ml, Fisher Scientific, Pittsburgh, PA). The 225 ml

sterile 0.1% peptone water (Cat. No. DFO1897-17-4, Detroit, MI) was poured into the

stomacher bag. The stomacher bag was manually massaged for two minutes to loose

surface bacteria. One milliliter of homogenate aliquot from stomacher bag was

transferred into a test tube containing 9 ml sterile 0.1% peptone water. Five tubes were

employed for each treatment from 10-2 to 10-6 serial dilutions. The contents of tubes

were mixed using vortex (Votex Geniz 2TM Cat. No. 12-812 Model G 250, Fisher









scientific, McGaw, IL) for 15 seconds to insure that the bacteria were evenly distributed.

Approximately 0.1 mL aliquot of the diluted sample homogenate from each serial

dilution was aseptically transferred into sterile disposable 100 x 20mm Petri plates (Cat.

No. 08-757-103C, Fisher Scientific, Suwanee, GA) that contained prepoured hardened

Tryptic Soy Agar (No.1010617, MP Biomedicals, Inc., Solon, OH). The homogenate

was spread on the plates using a sterile glass hockey stick. The stick was sterilized with

70% ethanol and flamed before spreading. The plates were incubated aerobically at 7C

for 10 days for total psychrotrophic counts (Hamm, 2001). Microbiological counts were

expressed as Logarithmic Colony Forming Units per grams (Log CFU/g). The counts

were recorded when 25-250 colonies were on the plate. All plates were done in

duplicates.

Objective Color Measurement

The color of raw and cooked fillets was measured with the Hunter MiniScan XE

plus colorimeter (Hunter Associates Laboratory Inc., Reston, VA). The colorimeter was

calibrated with a standard black tile and white tile as recommended by manufacturer.

Fillets (two fillets per package) were measured at a total of four different locations for L*,

a* and b* values. The instrumental color of L* a* b color spectrum was recorded,

where L* represents the total light reflected on a scale ranging from 0 = black to 100 =

white, a* represents the amount of red (positive values) and green (negative values),

and b value represents the amount of yellow (positive values) and blue (negative

values). All color measurements were performed in duplicates.

Warner-Bratzler Shear Force Analysis

The 1.0 cm cooked strips were employed for Instron shear force. The cooked 1.0

cm strips were covered with aluminum foil, and stored at 40C for 18 hours prior to









Instron measurements. Texture measurements were conducted as described by Lyon

and Lyon (1991). Each strip was oriented in the Warner-Bratzler shear attachment

(Type D. D., Catalog no. 2830-002), which was attached to the Model 1011 Instron

Texture machine (Model 1011, Instron Corporation, Norwood, MH). The speed of cross-

head was 200 mm/min with a 50 kg load cell. The full scale range was 10 kg (Williams

and Phillips, 1998). The Warner-Bratzler shear force values were recorded in kilograms.

Five values were obtained from each treatment. All treatments were done in duplicates.

Sensory Evaluation

Cooked meat was sectioned for sensory and instrumental texture measurements

as described by Lyon et al., (2005) with some minor changes. The fillets were cut into 2

to 3 cubic cm wide strips paralleled with the direction of fiber. One strip was separated

into three or four cubic cm for sensory evaluation, and another strip was used to

determine instrumental texture. The cubes were trimmed into uniform size. Two cubes

of each treatment were placed into a pre-warmed container to keep the serving

temperature at approximate 550C. The serving containers were labeled with one digit

numbers. The sensory evaluation was performed in the Meat Laboratory sensory room

equipped with eleven separated booths. Each booth was equipped with a ceiling lighting

system with red, white, blue, or yellow lighting as needed (Williams and Phillips, 1998).

The eight-point hedonic scoring scales were employed for juiciness, chicken flavor

intensity, and tenderness evaluation, where 8 represents extremely juicy, extremely

intense and extremely tender, 7 represents very juicy, very intense, and very tender, 6

represents moderately juicy, moderately intense, and moderately tender, 5 represents

slightly juicy, slight intense and slight tender, 4 represents slightly dry, slight bland and

slight tough, 3 represents moderately dry, moderately bland and moderately tough, 2









represents very dry, very bland and very tough, and 1 represents extremely dry,

extremely bland and extremely tough. A six-point scale was utilized for off-flavor

evaluation. 6 represents none detected, 5 represents threshold; barely detected, 4

represents slight off-flavor, 3 represents moderate off-flavor, 2 represents strong off-

flavor and 1 represents extreme off-flavor.

Statistical Analysis

The experiment was arranged in a complete randomized 5 (treatments) x7

(sampling days) factorial design and was replicated two times. Data were analyzed

using the GLM procedure of SAS (SAS Institute, 2002) by generating an analysis of

variance (ANOVA). The model included the main effects of antimicrobial treatment,

storage day, and treatment by day interaction. Data were re-analyzed within a day and

within a treatment. Comparisons among means were performed using SAS Duncan

Multiple Range test of the Statistical Analysis System. Treatments effects and

differences were considered significantly when P < 0.05. The MEANS procedure was

employed to analyze day and treatment.









CHAPTER 4
RESULTS AND DISCUSSION

Phase I. Preliminary Study: Application Method and Evaluation of Sodium
Metasilicate at Approved Level for Poultry Meat

Experiment 1

Marination yield analysis

The fillets treated with 1% and 2% sodium metasilicate had slightly higher

observed marination yields than control treatment (Figure 4-1). The data suggested that

sodium metasilicate had ability to bind more water under still-marination conditions.

pH and cooking yield analyses

The data demonstrated that meat pH values increased as the concentration of

sodium metasilicate levels increased. The pH value of control fillets and fillets treated

with 1% and 2% sodium metasilicate were 6.05, 6.65 and 6.85, respectively (Figure 4-2).

This is also true for the marinade solutions wherein pH increased with increased sodium

metasilicate levels (Figure 4-3).

Control fillets and fillets treated with 2% sodium metasilicate had higher cooking

yields than fillets treated with 1% sodium metasilicate (Figure 4-4). The higher cooking

yield for 2% may due to the water binding capacity of sodium metasilicate.

Microbiological analysis

The total psychrotrophic counts (TPC) for all treatments had too numerous to

count (TNTC) for dilution of 10 -1 and 10 -2 on day 0 (Table 4-1). The results indicated

that fillets treated with 2% sodium metasilicate had less observed psychrotrophic counts,

when compared to control fillets and fillets treated with 1% sodium metasilicate.









Objective color measurement

Raw fillet color. On day 0, the L* (lightness ) values of raw fillets treated with 0%

(Control, tap water), 1% and 2% sodium metasilicate solution were 58.48, 63.35, and

61.20, respectively (Table 4-2). Based on International Commission on Illumination

(CIE) lightness values for chicken breast meat, normal L* values (lightness) of fillets are

between 48 and 53, L* values of fillets less than 46 are considered dark, and L* values

of fillets greater than 53 are considered light for chicken meat (Qiao et al., 2002). L*

values higher than 60 are considered Pale, Soft, Exudative (PSE) (Van Laack et al.,

2000). Qiao et al. (2002) also reported the color change of three groups of breast meat

samples after overnight storage at 4C. The samples were chopped prior to measure,

the L*, a* and b* values of dark ground meat were 57.83, 5.01, and 9.05, respectively.

The L*, a* and b* values of normal ground meat were 62.07, 4.38 and 9.68,

respectively. And the L*, a* and b* values of light ground meat were 64.34, 3.75 and

9.55, respectively.

In this preliminary study, the sodium metasilicate treated samples were lighter (P >

0.05) than the control treatment. The control fillets were redder (P > 0.05) than sodium

metasilicate treatments on day 0 (Table 4-2). The control fillets were less yellow (P >

0.05) than fillets treated with sodium metasilicate on day 0. These results revealed that

sodium metasilicate treatments had higher L*, less a*, and higher b* values (P > 0.05),

when compared to the control fillets (Table 4-2).

Cooked fillet color. The data revealed that all treatments had similar (P > 0.05) a*

and b* values (Table 4-2). The control fillets had lighter (P < 0.05) cooked meat color

than fillets treated 2% sodium metasilicate, and darker (P < 0.05) than fillets treated with

1% sodium metasilicate.









Sensory evaluation and warner-bratzler shear force analyses

No significant differences (P > 0.05) were observed among treatments regarding

juiciness, chicken flavor intensity, tenderness and off-flavor sensory characteristics

(Table 4-3). All the treatments had similar (P > 0.05) Warner-Bratzler shear force (Table

4-3). The data revealed that these parameters were not influenced by the concentration

of sodium metasilicate in this preliminary study.

Experiment 2

In this preliminary study, the sampling days were 0, 1, 3, and 6. However, Off-odor,

slim formation and surface discoloration were detected in the samples on day 6,

therefore, collecting data for sensory evaluation, instrumental texture, cooked meat

color and cooking yield were discontinued after day 3.

Marination yield analysis

The control fillets and fillets treated with 2% sodium metasilicate had slightly

higher marination yield when compared to fillets treated with 1% sodium metasilicate

after marinated (Figure 4-5).

pH analysis

As concentration of sodium metasilicate increased, the pH of meat increased

(Table 4-4). The pH value of 2% sodium metasilicate treatment was significantly higher

(P < 0.05) than the control and 1% sodium metasilicate treatments over 6 days storage.

As storage time increased, the meat pH values of control treatment were similar (P >

0.05) over storage periods. The pH values of 1% sodium metasilicate treatment

decreased over storage time, and 2% sodium metasilicate treatment decreased on day

6 when compared to pH values of day 0.









Cooking yield analysis

Except for day 3, the cooking yield increased as the concentration of sodium

metasilicate increased (Figure 4-6). The cooking yield for 2% sodium metasilicate

treatment was higher than the control and 1% sodium metasilicate treatments through 3

days storage. The cooking yields for control and 2% sodium metasilicate treatments

slightly fluctuated (first decreased then increased) over storage time.

Microbiological analysis

The total psychrotrophic counts increased for all treatments as storage time

increased (Table 4-5). Except for day 3, the fillets treated with sodium metasilicate had

significantly lower (P < 0.05) total psychrotrophic counts through 6 days storage, when

compared to control treatment. No significant differences (P > 0.05) in total

psychrotrophic counts were detected between fillets treated with 1% and 2% sodium

metasilicate through 3 days storage. On day 6, the psychrotrophic counts for all

treatments had reached or exceeded 7 log cfu/g, and all samples had produced slime

formation and off-odor development.

Objective color measurement

Raw fillet color. The L* (lightness) values for control fillets were similar (P > 0.05)

with fillets treated with 1% and 2% sodium metasilicate on day 0 and day 1 (Table 4-6).

On day 3, the control fillets were significantly darker (P < 0.05) than fillets treated with

sodium metasilicate. The fillets treated with 1% sodium metasilicate had lower (P >

0.05) L* values on day 0, when compared with day 1 and day 3.

The control fillets had lower (P < 0.05) a* (redness) values than fillets treated with

1% sodium metasilicate on day 0. The fillets for all treatments had similar (P > 0.05) a*

values on day 1 and day 3.









The control fillets had lower (P < 0.05) b* yellownesss) values than fillets treated

with 2% sodium metasilicate on day 1. The fillets for all treatments were similar (P >

0.05) on day 0 and day 3.

Cooked fillet color. The fillets treated with 1% sodium metasilicate were darker

(P < 0.05) than control fillets on day 0 (Table 4-7). The fillets for all treatments were

similar L* (lightness) on day 0 and day 3. The control fillets were less red (P < 0.05)

than fillets treated with 1% and 2% sodium metasilicate on day 0. The control fillets

were redder (P < 0.05) than fillets treated with 2% sodium metasilicate on day 1. On day

3, all fillets had similar (P > 0.05) redness. The fillets treated with 1% sodium

metasilicate were yellower than control fillets and fillets treated with 2% sodium

metasilicate. All fillets were similar (P < 0.05) yellowness on day 1 and day 3.

Warner-bratzler shear force analysis

The Warner-Bratzler shear force value for all treatments fillets were less than 3.62,

which were indicative of very tender meat (Table 4-8). The Warner-Bratzler shear force

values were similar (P > 0.05) on day 0 and day 1 for all treatments. The fillets treated

with 2% sodium metasilicate had higher (P < 0.05) Warner-Bratzler shear force values,

when compared to control fillets and fillets treated with 1% sodium metasilicate.

Sensory evaluation

On day 0, the fillets treated with 1% and 2% sodium metasilicate were significantly

juicier (P < 0.05) than control fillets (Table 4-9). On day 1, all fillets had similar (P >

0.05) juiciness. On day 3, the fillets treated with 1% sodium metasilicate were

significantly juicer (P < 0.05) than fillets treated with 2% sodium metasilicate. As storage

time increased, only fillets treated with 2% sodium metasilicate decreased in juiciness









over 3 days storage, all other treatments fillets had similar (P > 0.05) juiciness through 3

days storage.

Chicken flavor intensity was similar (P > 0.05) for all treatments through 3 days

storage. The control fillets on day 3 had significantly (P < 0.05) stronger chicken flavor

intensity than day 1, all other treatment fillets had similar (P > 0.05) chicken flavor

intensity through 3 days storage.

Based on the responses of the panelists, overall tenderness varied from

moderately tender (6.14) to extremely tender (7.63). There was no significant difference

(P > 0.05) among treatments on individual sampling days. The sensory data indicated

that the panelists "barely" (score of 5) or "did not detect" (score of 6) off-flavor for all

treatments.

The effectiveness of sodium metasilicate at USDA approved level up to 2%

marinade solution did not extend shelf life, maintain the raw meat color discoloration,

and increased cooking yield and marination yield. However, the data were inconsistent

between the two preliminary experiments. Therefore, further investigation was

necessary to determine the effectiveness of sodium metasilicate at the USDA approved

levels and elevated levels on shelf life and meat quality.

Phase II. Preliminary Study: Determination of the Effectiveness of Sodium
Metasilicate at USDA Approved and Elevated Levels in a Shelf Life Study

Marination Yield Analysis

The fillets treated with sodium metasilicate had higher marination yields than

control fillets (Figure 4-7). Except for fillets treated with 2% sodium metasilicate, the

marination yield for all treatments slightly increased, as the concentration of sodium

metasilicate increased.









pH Analysis

In general, the pH of poultry meat increased, as the concentration levels of sodium

metasilicate increased (Table 4-10). The pH values of fillets treated with 4% sodium

metasilicate were significantly higher (P < 0.05) over 9 storage days, when compared

with control fillets and fillets treated with 1% sodium metasilicate. The pH values for 1%,

2%, 3%, and 4% sodium metasilicate marinade solutions were 12.42, 12.58, 12.75, and

12.83, respectively, these values were approximate 5 pH units higher than control

solution which was 7.71 (Figure 4-8). The fillets treated with sodium metasilicate were

expected to be more alkaline than control fillets. However, there was no significant

difference (P > 0.05) for pH values between control fillets and fillets treated with 1%

sodium metasilicate through 7 days storage. Except for day 7, the pH values of fillets

treated with 3% and 4% sodium metasilicate were similar (P > 0.05) over 9 days storage.

Except for fillets treated with 4% sodium metasilicate, all pH values of fillets among

treatments were similar (P > 0.05) on day 0.

Water-Holding Capacity Analyses

Water-holding capacity with sodium chloride

The results for water-holding capacity (WHC) measured with the standard method

(sodium chloride) are shown in Table 4-11. There were no significant differences in

WHC among treatments on days 0 through day 5. The WHC for all sodium metasilicate

treatments were consistently higher (P > 0.05), when compared to control treatment. On

day 7, the WHC of fillets treated with 1% and 4% sodium metasilicate were significantly

higher (P < 0.05), when compared to control fillets, and no difference (P > 0.05) was

detected among fillets treated with 1%, 2% and 3% sodium metasilicate. On day 9, the

WHC of fillets treated with 1% and 2% sodium metasilicate were significantly higher (P









> 0.05), when compared to control fillets, and were similar (P > 0.05) with fillets treated

with 3% and 4% sodium metasilicate. Except for the WHC of fillets treated with 3%

sodium metasilicate decreasing over storage time, the WHC of fillets for all treatments

were similar (P > 0.05) through 9 days storage.

Water-holding capacity with distilled water.

The WHC percentages for all treatments were similar (P > 0.05) on day 3 (Table 4-

12). On day 5, the WHC values for fillets treated with 1% sodium metasilicate were

significantly higher (P < 0.05), when compared to control fillets, and similar (P > 0.05)

among all other treatments. On day 7, the WHC values for fillets treated with 2% sodium

metasilicate were significantly lower (P < 0.05), when compared to control fillets. On day

9, the WHC values for fillets treated with 3% and 4% sodium metasilicate were

significantly higher (P < 0.05), when compared to control fillets and fillets treated with

1% sodium metasilicate.

Various methods have been developed or used to estimate meat WHC. For

example, drip loss, cooking yield, filter paper method and centrifugal method (Zhuang,

et al., 2008). In this experiment, the centrifuge method was used. The data (Table 4-11

and Table 4-12) indicated the uptake of added water by meat. The results of water

uptake in Table 4-11 indicated the effective of combination of sodium metasilicate and

sodium chloride. The results of water uptake in Table 4-12 indicated the effectiveness of

sodium metasilicate alone. The data suggested that sodium metasilicate had weaker

WHC, when compared to sodium chloride.

Cooking Yield Analysis

Although there was no statistical analysis of the data, the cooking yield values for

fillets treated with 4% sodium metasilicate were higher than the remaining fillets









treatments over 9 days storage (Figure 4-9). Except for fillets treated with 2% sodium

metasilicate on day 1, all fillets treated with sodium metasilicate had higher cooking

yield value than control fillets through 7 days storage. On day 9, only fillets treated with

1% sodium metasilicate had slightly lower cooking yields than control fillets. The

cooking yield values for all treatments on day 5 were lower than other sampling days.

The lower cooking yield values were attributed to the different storage method that was

used on day 5. On day 5, all panelists were unavailable. Therefore, fillets were stored in

the freezer overnight, and analyzed on the next day. Freezing treatment could alter the

spatial arrangement of the fibrillar network of meat, and would decrease the water

holding capacity. Therefore, much more liquid from meat would be released during

cooking, when compared to unfrozen meat.

Microbiological Analysis

In general, as storage time increased, the total psychrotrophic counts increased

for all treatments (Table 4-13). The fillets treated with 4% sodium metasilicate had

significantly lower (P < 0.05) psychrotrophic counts through 9 days storage, when

compared to control fillets and fillets treated with 1% and 2% sodium metasilicate.

Except for day 3, the fillets treated with 3% sodium metasilicate had significantly lower

(P < 0.05) psychrotrophic counts than control fillets over 9 days storage. The total

psychrotrophic counts for control fillets and fillets treated with 1% sodium metasilicate

had similar (P > 0.05) counts through 7 days storage. No microbial growth on plates

were detected for fillets treated with 3% and 4% sodium metasilicate on day 0 and day 1

at highest dilution plated, which was 10-2. In general, off-odor was detected when total

psychrotrophic counts reached 7 to 8 log cfu/g on meat surface and slime formation was

developed when total psychrotrophic counts were over 8 log cfu/g. On day 7, the









control fillets and fillets treated 1% and 2% sodium metasilicate were spoiled and the

total psychrotrophic counts had reached 7 logo cfu/g. On day 9, the fillets for all

treatments were spoiled, and the total psychrotrophic counts for all treatments

exceeded 8 log cfu/g. The data revealed that 1% and 2% sodium metasilicate

treatments did no significantly retard the microbial growth. The fillets treated with 3%

and 4% sodium metasilicate had significantly lower (P < 0.05) psychrotrophic counts

through 7 days storage, when compared to control fillets. The data demonstrated that

3% and 4% sodium metasilicate treatment retarded the growth for psychrotrophs and

increased the shelf life of the fillets at most to 2 additional days.

Objective Color Measurement

Raw fillet color

L* value. The fillets for most treatments became darker as storage time increased

(Table 4-14). On day 0, the fillets treated with 3% sodium metasilicate treatment were

significantly darker (P < 0.05) than control fillets and similar (P > 0.05) with all other

sodium metasilicate treatments. On day 5, the fillets treated with 1% and 2% sodium

metasilicate were significantly darker (P < 0.05) than control fillets and similar (P > 0.05)

to all other sodium metasilicate treatments. This effect was not observed at any other

storage intervals. As storage time increased, the L* values for fillets treated with 1%

sodium metasilicate were significantly lower (P < 0.05), when compared to day 0 and

day 9.

a* value. Except for day 0 and day 7, there was no significant difference (P > 0.05)

for a* values (Table 4-15), when compared to control fillets and fillets treated with

sodium metasilicate for other storage days. On day 0, the a* value for fillets treated with

1% sodium metasilicate were redder (P < 0.05) than fillets treated with 2% and 4%









sodium metasilicate. On day 7, the fillets treated with 3% sodium metasilicate were

significantly redder (P < 0.05) than control fillets and similar (P > 0.05) with other fillets

treated with sodium metasilicate. The a* values tend to increase as storage time

increased for all treatments. Myoglobin is responsible for the majority of the red color,

as storage time increased, the liquid released from the fillets increased, and the

concentration of myoglobin on the surface of meat increased.

b* value. The data indicated that b* values became greater as storage time

increased (Table 4-16). The b* values for control fillets and fillets treated with 4%

sodium metasilicate had slightly changed as storage time increased. The fillets treated

with 2%, 3% and 4% sodium metasilicate had similar (P > 0.05) b* values over 9 days

storage. On day 0 and day 1, fillets treated with 1% sodium metasilicate had

significantly higher (P < 0.05) b* value than fillets treated with 4% sodium metasilicate.

On day 9, fillets treated with 2% sodium metasilicate had lower (P < 0.05) b* value than

control fillets and similar (P > 0.05) with all other treatments.

Cooked fillet color

L* value. The fillets treated with 2%, 3% and 4% had similar (P > 0.05) L* values

as storage time increased (Table 4-17). Except for day 5, the control fillets and fillets

treated with 1% and 2% sodium metasilicate had similar L* values (P > 0.05) through 9

days storage. As storage time increased, the L* values for the control fillets and fillets

treated with 1% sodium metasilicate decreased (P < 0.05) slightly on day 9.

a* value. On day 0, the fillets treated with 1% sodium metasilicate had higher a*

value (P < 0.05), when compared to fillets treated with 2% and 4% sodium metasilicate

(Table 4-18). On day 7, the fillets treated with 3% sodium metasilicate had significantly









higher (P < 0.05) a* value, when compared to control fillets. Other fillets among

treatments were similar (P > 0.05) for all sampling days.

b* value. On day 0, control fillets and fillets treated with 1% sodium metasilicate

had higher (P < 0.05) b* values than fillets treated with 2% and 4% sodium metasilicate

(Table 4-19). On day 1, the fillets treated with 1% sodium metasilicate had greater (P <

0.05) b* value, when compared to fillets treated with 4% sodium metasilicate. On day 9,

the fillets treated with 2% sodium metasilicate had lower b* values than control fillets.

Fillets were similar (P > 0.05) for all other sampling days.

Warner-Bratzler Shear Force Analysis

Except for day 1, shear force values were similar (P > 0.05) for all treatments. On

day 1, the control fillets and fillets treated with 3% sodium metasilicate had lower (P <

0.05) shear force values than fillets treated with 1% sodium metasilicate. The shear

force values ranged from 1.18 kg to 2.03 kg for all treatments (Table 4-20). All samples

in this study were very tender based on the tenderness descriptions of Lyon and Lyon

(1991).

Sensory Evaluation

The panelists rated all samples slightly juicy (5.17) to very juicy (7.00) (Table 4-21).

Except for day 0, there was no significant difference in juiciness (P > 0.05) among all

treatments through 7 days storage. On day 0, the fillets treated with 3% sodium

metasilicate were juicier (P < 0.05), when compared to all fillets treated with 2% and 4%

sodium metasilicate. On day 9, the control fillets had similar (P >0.05) juiciness, when

compared to sodium metasilicate treated fillets, and the fillets treated with 2% and 3%

sodium metasilicate were juicier ( P < 0.05) than fillets treated with 1% sodium

metasilicate.









Except for day 0, the panelists rated the chicken flavor intensity for all treatments

similar (P > 0.05) for all storage days (Table 4-21). On day 0, the fillets treated with 3%

sodium metasilicate had greater (P < 0.05) chicken flavor intensity, when compared to

all other treatments.

Except for day 0, the panelists rated the tenderness of all treatments similar (P >

0.05) through 9 days storage (Table 4-22). The panelists rated all samples moderately

tender (6.33) to extremely tender (8.00). On day 0, the tenderness of fillets treated with

3% sodium metasilicate were significantly higher (P < 0.05) than all other treatments.

The fillets treated with 3% sodium metasilicate had a higher tenderness score on day 0

than on all other sampling days.

The panelists rated all treatments similar for off-flavor (P > 0.05) through 9 days

storage (Table 4-22). The data indicated that the panelists barely detected (score of 5)

or "did not detected" (score of 6) off-flavor development for all treatments.

Phase III. Investigation the Effectiveness of Sodium Metasilicate at the USDA
Approved and Elevated Levels on Antimicrobial, Sensory, Chemical and Physical
Characteristics of Fresh Chicken Breast Meat and Stored at 40C for 9 Days

Marination yield Analysis

In general, the marination yield increased, as the concentration levels increased

(Figure 4-10). The fillets treated with 1% sodium metasilicate had slightly higher

marination yield than the other sodium metasilicate treatments. In this study, all sodium

metasilicate treatments had slightly higher marination yield than control treatment.

pH Analysis

The fillets treated with 3% and 4% sodium metasilicate had significantly higher (P

< 0.05) pH values than the control fillets and fillets treated with 1% sodium metasilicate

over 9 days storage (Table 4-23). Except for day 3, the pH values were similar (P >









0.05) between the control fillets and fillets treated with 1% sodium metasilicate over 9

days storage. Except for day 7, the pH values were similar (P > 0.05) between fillets

treated with 2% and 3% sodium metasilicate. There was a slight decrease in trends for

treatments that contained sodium metasilicate over storage time. This may be due to

the production of various acid compounds by spoilage bacteria (Ruiz, 2007). The

microorganisms initially metabolized the glucose as energy, and later broke down small

compounds, such as amino acid. The metabolic processes resulted in the muscle meat

pH value decreasing. Liu et al. (2004) also reported that the pH values declined through

storage times. The complex biochemical reactions could lead to decrease in pH values.

Decreasing (P < 0.05) in pH values were observed for 2% sodium metasilicate

treatment on days 6 and 7, and for 3% and 4% sodium metasilicate treatments on day 9,

when compared to day 0 pH values.

Water-Holding Capacity Analyses

Water-holding capacity with sodium chloride.

The WHC values were expected to increase, as the pH values of fillets increased.

In this study, the WHC of fillets measured with sodium chloride had no significant

difference (P > 0.05) among treatments and over storage periods (Table 4-24).

Water-holding capacity with distilled water.

On day 1, the fillets treated with 3% sodium metasilicate had significantly higher (P

< 0.05) WHC than fillets treated with 1% sodium metasilicate (Table 4-24). On day 3,

the fillets treated with 1% and 3% sodium metasilicate had significantly higher (P < 0.05)

WHC values than control fillets. On day 7, the fillets treated with 4% sodium metasilicate

had significantly higher (P < 0.05) values than other fillets treated with sodium









metasilicate. Except for day 3, the values for fillets treated with 1% sodium metasilicate

treatments had similar (P > 0.05) with control fillets.

Purge Loss Analysis

In general, as storage time increased, the purge loss percentages for all

treatments increased (Table 4-25). The purge loss values were similar (P > 0.05)

among all treatments for 7 days storage. On day 9, the purge loss of 3% and 4%

sodium metasilicate treatments were significantly lower (P < 0.05) than all other

treatments.

Cooking Yield Analysis

On day 0, the cooking yields for fillets treated with 3% sodium metasilicate were

significantly higher (P < 0.05), when compared to all other treatments (Table 4-26). On

day 1, the cooking yields for all treatments were similar (P > 0.05). On day 3, the

cooking yields for fillets treated with 3% and 4% sodium metasilicate were higher (P <

0.05) than control fillets and fillets treated with 1% sodium metasilicate. On day 5, the

cooking yield for fillets treated with 3% and 4% sodium metasilicate were higher (P <

0.05) than all other treatments. On day 6, the cooking yields for fillets treated with 3%

were higher (P < 0.05) than control fillets and fillets treated with 4% sodium metasilicate.

The results indicated that the cooking yields for fillets treated with 3% sodium

metasilicate were higher through all storage days except for day 0.

Microbiological Analysis

In general, the total psychrotrophic counts increased as the storage time increased

for all treatments (Table 4-27). When the concentrations of antimicrobials increased, the

effectiveness of its properties increased. The total psychrotrophic counts for fillets

treated with 4% sodium metasilicate treatment were significantly lower (P < 0.05) than









control fillets and fillets treated with 1% sodium metasilicate through 9 days storage.

Except for day 0, there were no significant difference (P > 0.05) among control fillets

and fillets treated with 1% and 2% sodium metasilicate through 9 days storage. Except

for day 7, there was no significant difference (P > 0.05) among fillets treated with 3%

and 4% sodium metasilicate over storage time. Except for fillets treated with 2% sodium

metasilicate, the total psychrotrophic counts were similar (P > 0.05) for all treatments,

when compared to the initial day and day 1. From day 1 to day 5, the growth rate of

microbial accelerated for all treatments. On day 5, the control fillets and the fillets

treated 1% and 2% sodium metasilicate reached 8 log cfu/g, therefore, the samples

were spoiled. On day 6, the fillets for all treatments were spoiled. The results indicated

that the 3% and 4% sodium metasilicate treatments were effective to extend two

additional days for shelf life, when compared to control, 1% and 2% treatments.

When the means of the two trials were compared in phase III study, the total

psychrotrophic counts for the two trials were similar (P > 0.05) on day 0, but after day 3,

the total psychrotrophic counts for the two trials were higher by an average of 1- 2 log

cfu/g units than preliminary study through 7 days storage. Results from this study

suggested that the initial population of total psychrotrophic organisms was similar, but

the storage condition, handling of samples and incubation conditions may have

contributed to the acceleration of microbial growth.

Objective Color Measurement

Raw fillet color.

L* value. On the initial day, the color of fillets treated with 2% sodium metasilicate

were darker (P < 0.05), when compared to control fillets, and similar with the remaining

sodium metasilicate treatments (Table 4-28). On day 3, the color of fillets treated with









2% and 4% sodium metasilicate were darker (P < 0.05), when compared to control

fillets, and similar (P > 0.05) to other fillets treated with sodium metasilicate. On day 6,

the color of fillets treated with 3% sodium metasilicate were lighter (P < 0.05) than

control fillets and no significant differences (P > 0.05) were observed among all other

fillets treated with sodium metasilicate. On day 7, the fillets treated with 2%, 3% and 4%

sodium metasilicate were lighter (P < 0.05) than control fillets and no significant

differences (P > 0.05) were observed between control fillets and fillets treated with 1%

sodium metasilicate. On day 9, the fillets treated with 4% sodium metasilicate had

higher L* values (P < 0.05) than fillets treated with 1% sodium metasilicate. The control

fillets and fillets treated with 1% sodium metasilicate had similar (P > 0.05) over 9

storage days. The remaining fillets treated with sodium metasilicate were similar color

over 9 storage days.

The data indicated that the L* values for all treatments decreased as storage time

increased, when compared with day 0 and day 9. However, the greatest difference in L*

values change was observed in the control fillets. The L* values for control fillets were

similar (P > 0.05) through 3 days storage. From day 1 to day 3, the fillets treated with

1% sodium metasilicate increased 3 log units for total psychrotrophic counts. The

significantly L* values change for fillets treated with 1% sodium metasilicate may be due

to the drastic microbial growth after day 3. It was possible that the onset of spoilage in

the meat was on day 5 (control, 1%, and 2%) and on day 6 (3% and 4%). The bacteria

may have produced pigments on the meat surface. The data indicated that the microbial

counts increased 2 log units from day 3 to day 5, which might also explain the L* values

of control fillets changing after day 3. Therefore, sodium metasilicate could cause color









of fillets to become darker on the first three days storage, and also could maintain the L*

values for fillets treated with 3% and 4% sodium metasilicate treatments after day 3.

a* values: The fillets treated with sodium metasilicate had similar (P > 0.05) a*

values, when compared to control fillets over 6 days storage (Table 4-29). After day 6,

the control fillets were redder (P < 0.05) than all fillets treated with sodium metasilicate.

As storage time increased, the control fillets became redder. This may be explained that

as the storage time increased, the purge loss increased and the concentration of

myoglobin on the surface of the meat increased.

b* values: As storage time increased, the b* values increased (Table 4-30).

Except for day 0 and day 9, the b* values for fillets treated with 3% and 4% sodium

metasilicate were lower than ( P < 0.05) than control fillets through storage days. The

results demonstrated that the sodium metasilicate could retard the yellowness

development, when compared to control fillets.

Cooked fillet color

L* value. On day 0, the control fillets and fillets treated with 1% sodium

metasilicate were lighter (P < 0.05), when compared to fillets treated with 4% sodium

metasilicate, and were similar (P > 0.05) with remaining fillets (Table 4-31). On day 1,

the control fillets and fillets treated with 1% sodium metasilicate were lighter (P < 0.05),

when compared with remaining fillets treated with sodium metasilicate. On day 5, the

control fillets and fillets treated with 4% sodium metasilicate were darker (P < 0.05),

when compared to fillets treated with 3% sodium metasilicate.

a* value. The a* values were similar among control fillets and fillets treated with

1% sodium metasilicate through 6 days storage (Table 4-31). Also the a* values were

similar (P > 0.05) among fillets treated with 2% ,3% and 4% sodium metasilicate









through 6 days storage. The fillets treated with 4% sodium metasilicate were redder (P

< 0.05) than control fillets on day 0 and day 3.

b* values. Except for day 5, the b* values were similar (P > 0.05) for control fillets

and fillets treated with 1% sodium metasilicate through 6 days storage (Table 4-31).

Also the b* values were similar (P > 0.05) among fillets treated with 2%, 3% and 4%

sodium metasilicate through 6 days storage.

Several studies reported that there was significantly negative correlation between

the raw breast meat lightness (L*) and pH value (Allen et al., 1998). Allen et al. (1998)

reported that samples marinated with a solution containing 3% sodium tripolyphosphate

(STPP) and 7% sodium chloride had significantly higher L* (lightness) values and lower

a* (redness) values and b* yellownesss) values ,when compared to control samples.

Some researchers reported that samples marinated with 1% and 2% trisodium

phosphate had lower L* and higher a* values. Some studies reported that no color

differences were observed (P > 0.05) after meat was treated with sodium

tripolyphosphate (STPP). Some results reported that still marination with sodium

polyphosphate solution had higher L* (lightness) values for raw meat color. All of these

studies reported that the color changed after the meat was marinated with an alkaline

solution.

Warner-Bratzler Shear Force Analysis

Except day 1, no significant differences for Warner-Bratzler shear force values

were detected among all treatments through 6 days storage (Table 4-32). On day 1, the

control fillets and fillets treated with 4% sodium metasilicate were lower (P < 0.05),

when compared to fillets treated with 1%, 2% and 3% sodium metasilicate. Lyon and

Lyon (1991) reported that Warner-Bratzler shear force values less than 3.62 kg for









chicken breast meat were indicative of "very tender" meat. The Warner-Bratzler shear

force values for all treatments ranged from 1.82 kg to 2.86 kg, which was indicative of

very tender breast meat. The corresponding panelist scores were "moderately tender" to

"extremely tender" meat.

Sensory Evaluation

Juiciness

On day 0, the fillets treated with 3% and 4% sodium metasilicate were juicier (P <

0.05) when compared to the other treatments (Table 4-33). Based on the responses of

the panelists, on day 0, fillets treated with 1% sodium metasilicate were "slight dry" on

day 0. The control fillets and fillets treated with% and 2% sodium metasilicate were

"slight dry" to "slight dry" "slight juicy". The fillets treated with 3% and 4% sodium

metasilicate were "moderately juicy". Except for day 0, fillets for all treatments had

similar (P > 0.05) juiciness over 6 day storage. As storage time increased, the fillets

treated with 3% and 4% sodium metasilicate were similar (P > 0.05) over 6 days

storage.

Chicken flavor intensity

Except for day 0, the chicken flavor intensity for all treatments was similar (P >

0.05) through 6 days storage (Table 4-34). On day 0, the chicken flavor intensity for

fillets treated with 3% sodium metasilicate were higher (P < 0.05), when compared to

fillets treated with 1% sodium metasilicate, and were similar ( P > 0.05) with control

fillets and other fillets treated with sodium metasilicate.

Tenderness

Except for day 1, the tenderness of fillets in all treatments was similar (P > 0.05)

through 6 days storage (Table 4-34). On day 1, the fillets treated with 2% sodium









metasilicate were more tender (P < 0.05) when compared to control fillets. Lyon and

Lyon (1991) reported that there is a relationship between the objective shear forces

values and subjective sensory tests for tenderness in broiler chicken breast meat.

Off-flavor

None of the treatments developed off-flavor during 6 days of storage. All values

were on the range of "barely detected" (score of 5) to "none detected" (score of 6).












104.60
104.40
104.20
104.00 -
103.80
103.60
103.40
103.20
103.00 -


104.47


103.29



Control 1% SMS


2% SMS


Treatment


Figure 4-1. Marination yield percentages for boneless and skinless broiler chicken
breast meat marinated with sodium metasilicate and stored at 4C on day 0


7.00 -
6.80 -
6.60 -
6.40 -
6.20 -
6.00 -
5.80 -
5.60 -


6.85


6.65


6.05


Control


1% SMS


2% SMS


Treatment

Figure 4-2. pH value for boneless and skinless broiler chicken breast meat marinated
with sodium metasilicate and stored at 4C on day 0


104.51


I


I












14.00 -
12.00
10.00
8.00
6.00
4.00
2.00
0.00


12.42


12.58


7.61


Control


1% SMS


2% SMS


Treatment


Figure 4-3. pH of marinade solutions for boneless and skinless broiler chicken breast
meat marinated with sodium metasilicate and stored at 4C on day 0


61
60
59 -
598 -
57 -
586 -
575 -
564 -
55
54


60.30


56.61


54.78
_ _


Control


1% SMS
Treatment


2% SMS


Figure 4-4. Cooking yield percentages for boneless and skinless broiler chicken breast
meat marinated with sodium metasilicate and stored at 4C on day 0









Table 4-1. Total psychrotrophic counts for boneless and skinless broiler chicken breast
meat marinated with sodium metasilicate and stored at 40C on day 0
Treatment Dilution Al A2 B1 B2
Control 0.10 TNTC TNTC TNTC TNTC
0.01 250 252 377 332
1% SMS 0.10 TNTC TNTC TNTC TNTC
0.01 291 TNTC TNTC TNTC
2%SMS 0.10 TNTC TNTC TNTC TNTC
0.01 TNTC TNTC 84 86
Colony numbers between 25- 250 was counted;
TNTC = Colonies over 250 and it was too numerous to count;
SMS = Sodium metasilicate.

Table 4-2. Meat color measurement for boneless and skinless broiler chicken breast
meat marinated with sodium metasilicate and stored at 40C on day 0


Attribute


Treatment Raw L* Raw a* Raw b* Cooked L* Cooked a* Cooked b*
Control 58.48 7.27 14.62 82.15b 2.03 17.20
1% SMS 63.35 5.73 16.03 84.45a 1.62 16.61
2% SMS 61.20 6.51 17.22 79.59c 2.03 16.34
SEM 2.52 2.32 1.73 1.06 0.50 1.21
a-c Means in same column with different superscripts differ significantly (P < 0.05);
n = 3 values per mean;
SMS = Sodium metasilicate; SEM = Standard error of the mean.









Table 4-3. Sensory evaluation and Warner-Bratzler shear force for boneless and
skinless broiler chicken breast meat marinated with sodium metasilicate and
stored at 40C on day 0
Attribute
Chicken flavor Warner-Bratzler
Treatment Juiciness Intensity Tenderness off-flavor shear force, Kg
Control 5.00 6.50 5.50 5.50 6.41
1% SMS 4.00 6.00 5.50 4.50 6.06
2% SMS 4.00 6.00 5.00 4.50 7.41
SEM 1.15 0.91 0.58 0.71 1.48
n = 7 values per mean;
SMS = Sodium metasilicate; SEM = Standard error of the mean.


110.00
- 109.50
i 109.00
c 108.50
ca 108.00 -
a 107.50
107.00


109.40


108.50


108.00


Control


1% SMS


2% SMS


Treament


Figure 4-5. Marination yield percentages for boneless and skinless broiler chicken
breast meat marinated with sodium metasilicate and stored at 40C for 6 days


---------- F-









Table 4-4. pH measurement for boneless and skinless broiler chicken breast meat
marinated with sodium metasilicate and stored at 40C for 6 days
Storage time
Attribute Treatment d 0 d 1 d 3 d 6 SEM
pH Control 6.00cx 6.15bx 6.01 ,x 6.03b'x 0.10
1% SMS 6.46b'x 6.38b'x 6.38b'x 5.98b,y 0.10
2% SMS 6.84a,xy 7.04ax 6.62a,yz 6.39az 0.11
SEM 0.08 0.14 0.07 0.11
a-c Means in same column with different superscripts differ significantly (P < 0.05);
x-z Means in same row with different superscripts differ significantly (P < 0.05);
n = 3 values per mean;
SMS = Sodium metasilicate; SEM = Standard error of the mean.


100.00
90.00
80.00
70.00
60.00
50.00
40.00
30.00
20.00
10.00
0.00


Day 0


Day 1
Storage time


* Control
* 1% SMS
S2% SMS


Day 3


Figure 4-6. Cooking yield percentages for boneless and skinless broiler chicken breast
meat marinated with sodium metasilicate and stored at 40C for 6 days









Table 4-5. Total psychrotrophic counts for boneless and skinless broiler chicken breast
meat marinated with sodium metasilicate and stored at 4C for 6 days
Storage time
Attribute Treatment d 0 d 1 d 3 d 6 SEM
TPC, log cfu/g Control 6.55a,y 6.43a,y 6.77a'y 8.82ax 0.23
1% SMS 5.02bz 5.34bz 6.57ay 7.53cw 0.29
2% SMS 4.51bz 5.35b,y 6.73a'x 8.24b,w 0.15
SEM 0.17 0.21 0.32 0.18
a-c Means in same column with different superscripts differ significantly (P < 0.05);
x-z Means in same row with different superscripts differ significantly (P < 0.05);
n = 4 values per mean; TPC = Total psychrotrophic counts
SMS = Sodium metasilicate; SEM = Standard error of the mean.











Table 4-6. Objective raw meat color for boneless and skinless broiler chicken breast
meat marinated with sodium metasilicate and stored at 40C for 3 days
Storage time
Attribute Treatment d 0 d 1 d 3 SEM
L* Control 62.78ax 61.19ax 59.70b'x 2.85
1% SMS 55.60a,y 65.00ax 61.62ax 1.94
2% SMS 57.06ax 61.69ax 62.28ax 3.66
SEM 4.44 2.27 0.67


a* Control 3.82b,x 4.96ax 6.21ax 1.18
1% SMS 11.01ax 5.66a,y 6.79a,xy 2.09
2% SMS 6.99ab,x 7.54ax 6.56ax 0.85
SEM 2.11 1.30 0.69


b* Control 12.48a,y 14.99by 18.90ax 1.55
1% SMS 16.70ax 15.31ab,x 16.64ax 2.31
2% SMS 14.67ax 17.79ax 16.06ax 2.52
SEM 2.55 1.26 2.46
a-b Means in same column with different superscripts differ significantly (P < 0.05);
x-y Means in same row with different superscripts differ significantly (P < 0.05);
n = 3 values per mean;
SMS = Sodium metasilicate; SEM = Standard error of the mean.









Table 4-7. Objective cooked meat color for boneless and skinless broiler chicken breast
meat marinated with sodium metasilicate and stored at 40C for 3 days
Storage time
Attribute Treatment d 0 d 1 d 3 SEM
Cooked L* Control 84.25ax 84.03ax 79.62a,y 1.61
1% SMS 80.76b,y 84.13ax 79.95a,y 1.45
2% SMS 82.53ab,x 84.09ax 79.15a,y 1.36
SEM 1.30 1.28 1.79


Cooked a* Control 1.15b,y 2.03ax 1.85ax 0.33
1% SMS 2.62ax 1.74abx 1.73ax 0.71
2% SMS 2.58ax 1.23b,y 2.13ax 0.31
SEM 0.64 0.35 0.41


Cooked b* Control 16.07b'x 16.38ax 15.79ax 0.68
1% SMS 18.96ax 17.04a,xy 15.60a,y 1.03
2% SMS 16.17b,x 15.85ax 17.74ax 0.99
SEM 0.94 0.71 1.05
a-b Means in same column with different superscripts differ significantly (P < 0.05);
x-y Means in same row with different superscripts differ significantly (P < 0.05);
n = 3 values per mean;
SMS = Sodium metasilicate; SEM = Standard error of the mean.









Table 4-8. Warner-Bratzler shear force for boneless and skinless broiler chicken breast
meat marinated with sodium metasilicate and stored at 4C for 3 days
Storage time
Attribute Treatment d 0 d 1 d 3 SEM
Warner-Bratzler shear force, Kg Control 1.65a,y 2.07ax 1.68b,y 2.27
1% SMS 1.83ax 2.25ax 1.68b,x 0.47
2% SMS 1.63ax 2.20ax 2.12ax 0.36
SEM 0.33 0.51 0.24
a-b Means in same column with different superscripts differ significantly (P < 0.05);
x-y Means in same row with different superscripts differ significantly (P < 0.05);
n = 6 values per mean;
SMS = Sodium metasilicate; SEM = Standard error of the mean.









Table 4-9. Panelist rating for boneless and skinless broiler chicken breast meat
marinated with sodium metasilicate and stored at 40C for 3 days

Storage time
Attribute Treatment d 0 d 1 d 3 SEM


Juiciness


Chicken Flavor


Tenderness


Off-flavor


Control
1% SMS
2% SMS
SEM


Control
1% SMS
2% SMS
SEM


Control
1% SMS
2% SMS
SEM


Control
1% SMS
2% SMS


5.88b,x
6.88ax
7.13ax
0.71


5.75a,xy
5.50a',x
5.38ax
1.40


6.88a,xy
7.13ax
7.63a,x
0.86


5.75ax
5.88a,x
5.63a,x


5.29ax
5.86ax
5.57a'y
1.33


5.80ax
4. 00b,z


1.36


4.71ay 6.40a,x
5.14ax 6.20ax
4.71a,x 6.00axO


1.45


6.14a,y


0.63


7.20a,x


6.57a,x 7.20a,x


6.86a,x
1.04


7.60a,x
0.67


5.29ax 6.00ax
5.71a,x 6.00ax
5.57ax 6.00ax


SEM 0.70 0.90 0.00
a-b Means in same column with different superscripts differ significantly (P < 0.05);
x-y Means in same row with different superscripts differ significantly (P < 0.05);
n=10 values per mean; Sensory scale: Eight-point sensory scale for juiciness, chicken
flavor and tenderness where 8 = extremely juicy/intense/tender, 7 = very
juicy/intense/tender, 6 = moderately juicy/intense/tender, 5 = slightly
juicy/intense/tender, 4 = slightly dry/bland/tough, 3 = moderately dry/bland/tough, 2 =
very dry/bland/tough, 1 = extremely dry/bland/tough. A six-point scale for off-flavor
where 6 = none detected, 5 = threshold, barely detected, 4 = slight off-flavor, 3 =
moderate off-flavor, 2 = strong off-flavor, 1 = extreme off-flavor;
SMS = Sodium metasilicate; SEM = Standard error of the mean.


1.27
1.01
1.12


1.11
1.28
1.36


0.83
0.98
0.81


0.80
0.36
0.80











110.00. 109.33 108.65 109.52 109.95

108.00 -

106.00
0 103.91
104.00

102.00

100.00
Control 1% SMS 2% SMS 3% SMS 4% SMS
Treatment

Figure 4-7. Marination yield percentages for boneless and skinless broiler chicken
breast meat marinated with sodium metasilicate and stored at 4C for 9 days

































93









Table 4-10. pH measurement for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate
and stored at 4C for 9 days
Storage time
Attribute Treatment 0 d 1 d 3 d 5 d 7 d 9 d SEM
pH Control 6.55bx 6.56cx 6.30cz 6.45cy 6.39dy 6.22cz 0.11
1% SMS 6.86bx 6.69c,xy 6.62c,xy 6.65c,xy 6.46dy 6.63b,xy 0.10
2% SMS 7.07bx 6.91bx 6.91ab,x 6.78ab,x 6.70cx 6.75b'x 0.16
3% SMS 7.36ab,x 7.31ax 7.09a,x 7.08ab,x 6.89b 6.90ab,x 0.22
4% SMS 8.00ax 7.43a,y 7.06a,y 7.16a,y 7.30a,y 7.11a,y 0.21
SEM 0.31 0.08 0.13 0.13 0.03 0.12
a-c Means in same column with different superscripts differ significantly (P < 0.05);
x-z Means in same row with different superscripts differ significantly (P < 0.05); n = 4 values per mean;
SMS = Sodium metasilicate; SEM = Standard error of the mean.











14.00
13.00 12.42 12.58 12.75 12.83
12.00 -
= 11.00
S10.00 -
9.00
8.00 7.61
7.00
Control 1%SMS 2% SMS 3% SMS 4% SMS
Treatment


Figure 4-8. Marinade solution of pH for boneless and skinless broiler chicken breast meat marinated with sodium
metasilicate and stored at 4C on day 0










Table 4-11. Water-holding capacity percentages for boneless and skinless broiler chicken breast meat marinated with
sodium metasilicate and stored at 4C for 9 days: WHC with sodium chloride


Storage time
Attribute Treatment 0 d 1 d 3 d 5 d
WHC-NaCI, % Control 117.14ax 131.52ax 92.77a'x 142.99ax
1% SMS 148.86ax 142.98ax 142.78a'x 148.52a'x
2% SMS 130.39ax 153.39ax 143.05a'x 143.16ax
3% SMS 147.03 a' 144.08a,xy 146.65awx 143.72a,y
4% SMS 144.55ax 149.82a'x 148.51ax 152.33ax
SEM 19.83 13.25 29.40 8.56
a-c Means in same column with different superscripts differ significantly (P < 0.05);
w-z Means in same row with different superscripts differ significantly (P < 0.05); n = 2
WHC = Water-holding capacity; NaCI = Sodium chloride;
SMS = Sodium metasilicate; SEM = Standard error of the mean.


7d
134.99Cx'
147.41ab,x
142.55abc,x
140.16bc,z
152.19ax
4.12


9d
119.02bx
145.57ax
142.13a,x
140.10ab,z
139.33ab'x
8.14


values per mean;


SEM
32.69
2.55
13.43
2.84
8.48









Table 4-12. Water-holding capacity percentages for boneless and skinless broiler chicken breast meat marinated with
sodium metasilicate and stored at 4C for 9 days: WHC with distilled water only
Storage time
Attribute Treatment 3 d1 5 d 7 d 9 d SEM
WHC water, % Control 35.76a,xy 29.94bxy 62.50ax 17.74c,y 12.76
1% SMS 33.25a,yz 56.37ax 48.79ab,xy 18.44cz 6.65
2% SMS 39.72ax 52.97ab,x 31.09b,x 25.28bc'x 13.21
3% SMS 28.75a,y 52.97ab,x 57.88ab,x 36.44ab,y 2.84
4% SMS 58.39ax 36.85ab,x 58.63ab,x 42.35ax 10.32
SEM 12.45 8.96 11.43 5.56
a-c Means in same column with different superscripts differ significantly (P < 0.05);
x-z Means in same row with different superscripts differ significantly (P < 0.05);
1 the data were available from day 3; n = 2 values per mean;
WHC = Water-holding capacity; NaCI = Sodium chloride;
SMS = Sodium metasilicate; SEM = Standard error of the mean.













100.00
90.00
c 80.00 -Control
Od 70.00 1% SMS
.T 60.00
>- 50.00 -E2%SMS
40.00
30.00 3% SMS
o 20.00 -E4%SMS
o 10.00
S0.00 -
Od Id 3d 5d 7d 9d
Storage time

Figure 4-9. Cooking yield percentages for boneless and skinless broiler chicken breast meat marinated with sodium
metasilicate and stored at 4C for 9 days









Table 4-13. Total psychrotrophic counts for boneless and skinless broiler chicken breast meat marinated with sodium
metasilicate and stored at 4C for 9 days
Storage time
Attribute Treatment 0 d 1 d 3 d 5 d 7 d 9 d SEM
TPC, log cfu/g Control 3.91a,z 4.21a,yz 4.59ab,y 6.48a,x 7.93aw 8.74bv 0.19
1% SMS 3.95az 3.81ab,yz 4.97a,y 6.19ab,xy 7.95a,wx 9.11aw 1.11
2% SMS 2.94b'z 3.50a'y 4.30abx 5.53bc,w 7.75a'v 8.72b'u 0.22
3% SMS l0.00C'Z 0.00b,z 3.93by 5.15c,x 6.51bw 8.12cv 0.29
4% SMS 0.OO0c' 0.00b,z 2.94cy 3.99dx 6.29bw 8.01 ,v 0.19
SEM 0.22 1.21 0.28 0.26 0.23 0.11
a-d Means in same column with different superscripts differ significantly (P < 0.05);
u-z Means in same row with different superscripts differ significantly (P < 0.05); n = 4 values per mean;
1 Means the plates counts fewer than 25 cfu, the counts from plates less than 2500/g.
TPC = Total psychrotrophic counts
SMS = Sodium metasilicate; SEM = Standard error of the mean.









Table 4-14. Objective raw meat color L* values on boneless and skinless broiler chicken breast meat marinated with
sodium metasilicate and stored at 4C for 9 days
Storage time
Attribute Treatment 0 d 1 d 3 d 5 d 7d 9 d SEM
L* Control 62.65a'x 61.27a,xy 60.07a,xy 58.44a,y 61.45a,xy 57.83a,y 1.99
1% SMS 62.23abx 57.00a,yz 63.04a'x 55.39b'z 60.43a,xy 54.92az 2.38
2% SMS 60.94abx 57.65a'x 49.48a'x 55.19bx 58.68a'x 58.02ax 7.25
3% SMS 58.98b'x 56.64ax 58.69a'x 56.56abx 59.55ax 56.92ax 2.21
4% SMS 60.75ab,x 60.12ax 60.65ax 56.57abx 57.42a'x 57.28a'x 2.32
SEM 1.85 2.48 7.83 1.49 2.77 2.50


a-c Means in same column with different superscripts differ significantly ( P < 0.05);
x-z Means in same row with different superscripts differ significantly (P < 0.05); n = 6
SMS = Sodium metasilicate; SEM = Standard error of the mean.


values per mean;


100









Table 4-15. Objective raw meat color a* values for boneless and skinless broiler chicken breast meat marinated with
sodium metasilicate and stored at 4C for 9 days


Storage time
Attribute Treatment 0 d 1 d 3 d 5 d 7 d 9 d SEM
a* Control 5.30ab,yz 6.49axyz 7.37ax 6.40axyz 4.92b'z 6.99axy 0.99
1% SMS 6.18ax 6.77ax 6.23ax 6.85ax 6.71ab,x 7.51ax 1.27
2% SMS 5.18b,x 6.60ax 6.06ax 7.03ax 5.94ab 5.27ax 1.20
3% SMS 5.70ab,x 6.93ax 6.52ax 6.65ax 7.52ax 7.1 0ax 1.14
4% SMS 4.91b,z 5.54a,yz 5.40ayz 6.58a,xy 7.34abx 7.87ax 0.80
SEM 0.51 1.18 1.02 0.99 1.27 1.39


values per mean;


a-c Means in same column with different superscripts differ significantly ( P < 0.05);
x-z Means in same row with different superscripts differ significantly (P < 0.05); n = 6
SMS = Sodium metasilicate; SEM = Standard error of the mean.









Table 4-16. Objective raw meat color b* values for boneless and skinless broiler chicken breast meat marinated with
sodium metasilicate and stored at 4C for 9 days
Storage time
Attribute Treatment 0 d 1 d 3d 5 d 7 d 9 d SEM
b* Control 15.79ab,y 16.57ab,y 16.68a,y 18.68a,xy 17.12a,y 23.15ax 2.14
1% SMS 16.96ax 18.40ax 17.45a'x 17.1ax 18.94a,y 19.43abx 1.79
2% SMS 13.42bc,x 15.98ab,x 14.81a'x 16.21ax 17.51ax 13.92b'x 2.80
3% SMS 14.54abc,x 13.84abx 15.78a'x 16.12ax 17.66a'x 18.92ab,x 2.65
4% SMS 12.48c'y 14.69b'xy 14.47a'xy 15.23a,xy 16.20a,xy 17.49ab'x 2.09
SEM 1.69 2.22 1.93 1.79 2.78 3.13
a-c Means in same column with different superscripts differ significantly (P < 0.05);
x-z Means in same row with different superscripts differ significantly (P < 0.05); n = 6 values per mean;
SMS = Sodium metasilicate; SEM = Standard error of the mean.


102









Table 4-17. Objective cooked meat color L* values for boneless and skinless broiler chicken breast meat marinated with
sodium metasilicate and stored at 4C for 9 days


Storage time
Attribute Treatment 0 d 1 d 3 d 5 d
L* Control 62.65a'x 61.27a,xy 60.07a,xy 58.44a'y
1% SMS 62.23abx 57.00a,yz 63.04a'x 55.39bz
2% SMS 60.94abx 57.65a'x 49.48a'x 55.19bx
3% SMS 58.98b'x 56.64ax 58.69ax 56.56ab'x
4% SMS 60.75ab,x 60.12ax 60.65ax 56.57ab'x
SEM 1.85 2.48 7.83 1.49
a-c Means in same column with different superscripts differ significantly (P < 0.05);
x-z Means in same row with different superscripts differ significantly (P < 0.05); n = 6
SMS = Sodium metasilicate; SEM = Standard error of the mean.


7 d 9 d SEM
61.45a'xy 57.83a'y 1.99
60.43a,xy 54.92a'z 2.38
58.68ax 58.02a'x 7.25
59.55ax 56.92a'x 2.21
57.42ax 57.28a'x 2.32
2.77 2.50


values per mean;


103









Table 4-18. Objective cooked meat color a* values for boneless and skinless broiler chicken breast meat marinated with
sodium metasilicate and stored at 4C for 9 days


Storage time


Attribute Treatment 0 d 1 d 3 d 5 d 7 d 9 d SEM
a* Control 5.30ab,yz 6.49axyz 7.37ax 6.40axyz 4.92b'z 6.99axy 0.99
1% SMS 6.18ax 6.77ax 6.23ax 6.85ax 6.71ab,x 7.51ax 1.27
2% SMS 5.18b,x 6.60ax 6.06ax 7.03ax 5.94abx 5.27a'x 1.2
3% SMS 5.70abx 6.93ax 6.52ax 6.65ax 7.52ax 7.10ax 1.14
4% SMS 4.91b,z 5.54a,yz 5.40a,yz 6.58a,xy 7.34abx 7.87ax 0.8
SEM 0.51 1.18 1.02 0.99 1.27 1.39


values per mean;


a-c Means in same column with different superscripts differ significantly (P < 0.05);
x-z Means in same row with different superscripts differ significantly (P < 0.05); n = 6
SMS = Sodium metasilicate; SEM = Standard error of the mean.









Table 4-19. Objective raw meat color b* values for boneless and skinless broiler chicken breast meat marinated with
sodium metasilicate and stored at 4C for 9 days
Storage time
Attribute Treatment 0 d 1 d 3 d 5 d 7d 9 d SEM
b* Control 15.79ab,y 16.57ab,y 16.68a,y 18.68a,xy 17.12a,y 23.15ax 2.14
1% SMS 16.96ax 18.40ax 17.45a'x 17.10ax 18.94ax 19.43abx 1.79
2% SMS 13.42bc,x 15.98ab,x 14.81ax 16.21ax 17.51ax 13.92b'x 2.8
3% SMS 14.54abcx 13.84abx 15.78ax 16.12ax 17.66ax 18.92ab,x 2.65
4% SMS 12.48c'y 14.69b'xy 14.47a'xy 15.23a,xy 16.20a,xy 17.49ab'x 2.09
SEM 1.69 2.22 1.93 1.79 2.78 3.13
a-c Means in same column with different superscripts differ significantly (P < 0.05);
x-z Means in same row with different superscripts differ significantly (P < 0.05); n = 6 values per mean;
SMS = Sodium metasilicate; SEM = Standard error of the mean.


105









Table 4-20. Warner-Bratzler shear force for boneless and skinless broiler chicken breast meat marinated with sodium
metasilicate and stored at 4C for 9 days


storage time
Attribute Treatment 0 d 1 d 3 d 5 d
Warner-Bratzler shear force, Kg Control 1.65a,x 1.18cy 1.55a,xy 1.83ab,x
1% SMS 1.82a,xy 1.80a,xy 1.70a,xy 2.03ax
2% SMS 1.91a'x 1.36abc,y 1.51a,xy 1.58b,xy
3% SMS 1.78a'x 1.32bc,y 1.52a,xy 1.69ab,xy
4% SMS 1.53a,xy 1.66ab,xy 1.53a,xy 1.88ab,x
SEM 0.37 0.36 0.40 0.34
a-b Means in same column with different superscripts differ significantly (P < 0.05);
x-y Means in same row with different superscripts differ significantly (P < 0.05); n = 6 values
SMS = Sodium metasilicate; SEM = Standard error of the mean.


7d 9d SEM
1.54a,xy 1.40a,xy 0.35
1.58a,xy 1.50a,y 0.38
1.55a,xy 1.41a,y 0.35
1.49a,xy 1.62a,xy 0.31
1.41a,y 1.54a,xy 0.29
0.30 0.25


per mean;


106









Table 4-21. Panelist rating for juiciness and chicken flavor intensity for boneless and skinless broiler chicken breast meat
marinated with sodium metasilicate and stored at 40C for 9 days
Storage time
Attribute Treatment 0 d 1 d 3 d 5 d 7d 9 d SEM
Juiciness Control 6.83ab'x 6.43a,xy 6.50a,xy 5.29a,y 6.33a,xy 5.75abxy 1.26
1% SMS 6.83ab'x 6.86a'x 6.33a,xy 6.00a,xy 6.56a'x 4.88b,y 1.32
2% SMS 5.50bc,x 5.71a,x 7.00a,x 6.14a'x 6.44a'x 6.25a'x 1.29
3% SMS 8.00a'x 6.43a,y 6.00a,y 5.43a,y 5.89a,y 6.38a,y 1.21
4% SMS 5.17cx 6.29a'x 6.00ax 6.14a'x 6.33a'x 5.50abx 1.20
SEM 1.20 1.52 1.15 1.40 1.09 1.17

Chicken Flavor Control 6.50b'x 6.43a'x 6.00ax 5.71a,x 5.67a,x 5.75a,x 1.43
1% SMS 6.50b,x 6.43a'x 6.00ax 6.14ax 5.56ax 5.25ax 1.43
2% SMS 6.33b,x 5.86ax 6.00ax 6.14a'x 5.22a'x 5.38a'x 1.44
3% SMS 8.00ax 6.00a,y 5.67a,y 5.86a,y 5.44a,y 5.13ax 1.57
4% SMS 6.00b,x 6.00a'x 5.50a,x 6.00ax 5.56ax 5.00a,x 1.63
SEM 1.03 0.94 0.96 1.59 1.60 2.16


a-c Means in same column with different superscripts differ significantly (P < 0.05);
x-y Means in same row with different superscripts differ significantly (P < 0.05); n =


10 values per mean;


Sensory scale: Eight-point sensory scale for juiciness, chicken flavor where 8 = extremely juicy/intense, 7 = very
juicy/intense, 6 = moderately juicy/intense, 5 = slightly juicy/intense, 4 = slightly dry/bland, 3 = moderately dry/bland, 2 =
very dry/bland, 1 = extremely dry/bland;
SMS = Sodium metasilicate; SEM = Standard error of the mean.









Table 4-22. Panelist rating for tenderness and off-flavor for boneless and skinless broiler chicken breast meat marinated
with sodium metasilicate and stored at 4C for 9 days
Storage time
Attribute Treatment 0 d 1 d 3 d 5 d 7 d 9 d SEM
Tenderness Control 7.17abx 7.29ax 7.50ax 6.71a,x 7.00a,x 7.13a'x 1.01
1% SMS 6.83b'x 7.29ax 7.17a'x 7.00ax 7.00ax 6.75a'x 1.19
2% SMS 6.67b'x 6.86a'x 7.67a,x 7.29ax 7.33a,x 7.13ax 1.01
3% SMS 8.00ax 7.14a,xy 7.67a,xy 6.86a,y 7.00a,xy 7.38a,xy 0.91
4% SMS 6.33b,x 7.14ax 7.17a'x 6.86ax 7.11ax 6.88a'x 1.06
SEM 0.90 1.15 0.63 1.07 1.08 1.19

Off-flavor Control 6.00ax 5.71a,x 6.00a,x 6.00ax 5.56a'x 5.63a'x 0.65
1% SMS 6.00ax 5.71ax 6.00a,x 5.86a'x 5.56a'x 5.75a'x 0.57
2% SMS 5.67ax 5.57ax 5.83a'x 6.00ax 5.78a'x 5.75a'x 0.54
3% SMS 6.00ax 5.57ax 5.33a'x 6.00ax 5.78a'x 5.75a'x 0.62
4% SMS 5.67ax 5.57ax 5.67a'x 5.86a'x 5.67a'x 5.62a'x 0.64
SEM 0.52 0.58 0.68 0.24 0.8 0.59
a-b Means in same column with different superscripts differ significantly (P < 0.05);
x-y Means in same row with different superscripts differ significantly (P < 0.05); n = 10 values per mean;
Sensory scale: Eight-point sensory scale for tenderness where 8 = extremely tender, 7 = very tender, 6 = moderately
tender, 5 = slightly tender, 4 = slightly tough, 3 = moderately tough, 2 = very tough, 1 = extremely tough. A six-point scale
for off-flavor where 6 = none detected, 5 = threshold, barely detected, 4 = slight off-flavor, 3 = moderate off-flavor, 2 =
strong off-flavor, 1 = extreme off-flavor;
SMS = Sodium metasilicate; SEM = Standard error of the mean.


108













109.50 -
S109.00 108.89 108.65 108.43
c 108.50 108.06
0
4. 108.00 -
107.50 -
107.00
106.50
Control 1%SMS 2% SMS 3% SMS 4% SMS
Treatment
Figure 4-10. Marination yield percentages for boneless and skinless broiler chicken
breast meat marinated with sodium metasilicate and stored at 4C for 9 days


109









Table 4-23. Mean pH measurements for boneless and skinless broiler chicken breast meat marinated with sodium
metasilicate and stored at 4C for 9 days
Storage time
Attribute Treatment 0 d 1 d 3 d 5d 6 d 7 d 9 d SEM
pH Control 6.29b'z 6.57c,wxy 6.29 6.42c,yz 6.44c,xyz 6.71b 6.67b,wx 0.15
1% SMS 6.72bx 6.65cx 6.60cx 6.66bc,x 6.57Cx 6.75b'x 6.70b,x 0.18
2% SMS 7.28a'x 7.08b,xy 6.99b,xy 6.96ab,xy 6.75bc,y 6.79b,y 7.03a,xy 0.29
3% SMS 7.40ax 7.40ab,x 7.21b,xy 7.08a,xy 6.98ab,y 7.03a,xy 7.00a,y 0.24
4% SMS 7.61a,xy 7.69a,x 7.71a,x 7.27a,xyz 7.16a,yz 7.22a,xyz 6.99a'z 0.31

SEM 0.37 0.88 0.16 0.25 0.25 0.14 0.18
a-c Means in same column with different superscripts differ significantly (P < 0.05);
w-z Means in same row with different superscripts differ significantly (P < 0.05); n = 4 values per mean;
SMS = Sodium metasilicate; SEM = Standard error of the mean.


110









Table 4-24. Mean water-holding capacity percentages for boneless and skinless broiler chicken breast meat marinated
with sodium metasilicate and stored at 40C for 9 days: WHC with sodium chloride and distilled water
Storage time


Attribute
WHC-Nacl, %










WHC-Water, %


Treatment
Control
1% SMS
2% SMS
3% SMS
4% SMS
SEM


Control
1% SMS
2% SMS
3% SMS
4% SMS
SEM


Od
144.98
143.38
149.06
148.28
147.42
6.85


28.04a,xy
30.56a'xy
34.95ax
35.93ax
40.06ax
10.83


1 d
137.17
142.49
148.25
148.07
148.24
9.27


33.37ab,xy
24.84b,xy
28.97ab,xy
36.56ax
35.00ab,xy
6.80


3d
135.66
147.06
146.47
148.13
143.50
13.08


18.44b,y
21.41a,xy
28.63ab,xy
30.69a,x
25.57ab,y
6.89


5d
146.55
147.75
146.58
144.05
144.81
4.63


25.78a,y
26.97a,xy
31.14ax
25.45ax
33.52a,xy
8.03


6d
147.17
148.85
145.11
143.14
145.78
6.08


19.50a,y
19.48a,y
21.32a'y
23.29ax
25.25a'y
4.50


7d
144.67
148.26
148.52
147.05
148.32
2.83


31.57ab,xy
25.52b,xy
27.54b,x
24.90b,x
39.60a,x
6.13


a-b Means in same column with different superscripts differ significantly (P < 0.05);
x-y Means in same row with different superscripts differ significantly (P < 0.05); n = 4 values per mean;
WHC = Water-holding capacity; NaCI = Sodium chloride
SMS = Sodium metasilicate; SEM = Standard error of the mean.


9d
146.94
147.26
146.57
149.37
147.91
3.27


42.37a,x
32.29a,x
29.20a,xy
32.47ax
34.24a,xy
11.36


SEM
12.30
6.56
3.66
6.54
4.64



9.96
7.51
5.62
8.66
8.27









Table 4-25. Mean purge loss percentages for boneless and skinless broiler chicken breast meat marinated with sodium
metasilicate and stored at 4C for 9 days
Storage time
Attribute Treatment 0 d 1 d 3 d 5 d 6 d 7 d 9 d SEM
Purge loss, % Control 6.70ax 6.64ax 6.29ax 7.63ax 6.39ax 7.09ax 10.45abx 2.97
1% SMS 5.59ax 4.94ax 6.89ax 6.10ax 5.68ax 6.47ax 10.21bx 3.55
2% SMS 4.75a,y 6.20a,xy 6.75a,xy 6.68a,xy 5.64a,y 6.57a,xy 11.25a'x 3.35
3% SMS 4.17ax 4.94ax 5.11ax 7.17ax 5.53ax 5.32ax 8.68cx 3.64
4% SMS 4.97ax 4.33ax 4.50ax 5.70ax 4.13ax 5.56ax 8.29cx 3.67
SEM 3.19 3.59 4.20 3.40 3.66 4.14 0.53
a-c Means in same column with different superscripts differ significantly (P < 0.05);
x-y Means in same row with different superscripts differ significantly (P < 0.05); n = 4 values per mean;
SMS = Sodium metasilicate; SEM = Standard error of the mean.


112









Table 4-26. Mean cooking yield percentages for boneless and skinless broiler chicken breast meat marinated with
sodium metasilicate and stored at 4C for 6 days
Storage time
Attribute Treatment 0 d 1 d 3 d '5 d 16 d SEM
Cooking yield, % Control 80.35bc,xy 80.72a,x 74.81bz 75.32b,yz 81.24cx 2.74
1% SMS 79.13c'xy 80.77a,xy 69.09,z 75.04b,yz 85.01abc,x 4.83
2% SMS 86.41 b,x 80.43a,xy 78.83aby 73.60b,y 88.24abx 3.90
3% SMS 93.03ax 85.25a,yz 81.90a'z 86.29axy 85.93a,xy 3.28
4% SMS 85.66bx 86.96ax 82.38ax 85.22ax 86.81bc,x 3.13
SEM 3.92 4.64 2.76 3.94 1.81
a-c Means in same column with different superscripts differ significantly (P < 0.05);
x-z Means in same row with different superscripts differ significantly (P < 0.05); n = 4 values per mean;
1 on trial II, only 3% and 4% treatments were not spoiled on 5 d and 6 d;
SMS = Sodium metasilicate; SEM = Standard error of the mean.


113









Table 4-27. Mean total psychrotrophic counts for boneless and skinless broiler chicken breast meat marinated with
sodium metasilicate and stored at 4C for 9 days
Storage time
Attribute Treatment 0 d 1 d 3 d 5 d 6 d 7d 9 d SEM
TPC, log cfu/g Control 4.27az 4.20az 6.54a,y 8.56ax 8.97awx 9.50aw 9.69aw 0.52
1% SMS 3.80az 3.93az 6.40a,y 8.23a'x 8.91a,w 9.41 a, 9.33ab,w 0.46
2% SMS 0.68b,z 2.89ay 5.76ab,x 8.44aw 8.74ab,w 9.44aw 9.38ab,w 0.96
3% SMS 10.00bz 0.00b,z 4.78b,y 6.81b,x 7.84abx 9.16a, 9.07bcw 0.76
4% SMS 0.00b,z 0.00b,z 4.99b,y 6.22b'x 8.02b'w 8.42b'w 8.74cw 0.69
SEM 0.76 1.00 0.77 0.80 0.64 0.31 0.34
a-c Means in same column with different superscripts differ significantly (P < 0.05);
w-z Means in same row with different superscripts differ significantly (P < 0.05); n = 4 values per mean;
1 means the plates counts fewer than 25 CFU, the counts from plates less than 2500/g;
TPC = Total psychrotrophic counts;
SMS = Sodium metasilicate; SEM = Standard error of the mean.









Table 4-28. Mean objective raw meat color L* values for boneless and skinless broiler chicken breast meat marinated
with sodium metasilicate and stored at 4C for 9 days
Storage time
Attribute Treatment 0 d 1 d 3 d 5 d 6 d 7 d 9 d SEM
L* Control 62.83a'w 60.00a'wx 59.97a'wx 57.08a'xy 55.54b,yz 52.91c,z 55.80abyz 2.11
1% SMS 61.57ab'w 59.47a'wx 57.81ab,xy 57.46axy 56.30ab,yz 55.78bc,yz 55.44b,z 1.65
2% SMS 59.38b,x 58.32a,xy 56.61b,xy 58.63axy 57.35abxy 58.11 ab,xy 55.33ab,y 2.39
3% SMS 61.00ab,x 59.15ax 58.90abx 58.37ax 58.52a'x 60.45a'x 58.09abx 2.16
4% SMS 60.10ab,x 58.42a,xy 56.70b,y 57.59axy 56.15ab,y 58.69abxy 58.82axy 2.02
SEM 1.83 2.20 1.78 2.29 1.75 2.12 2.47
a-c Means in same column with different superscripts differ significantly (P < 0.05);
x-z Means in same row with different superscripts differ significantly (P < 0.05); n = 16 values per mean;
SMS = Sodium metasilicate; SEM = Standard error of the mean.


115









Table 4-29. Mean objective raw meat color a* values for boneless and skinless broiler chicken breast meat marinated
with sodium metasilicate and stored at 4C for 9 days
Storage time
Attribute Treatment 0 d 1 d 3 d 5 d 6 d 7d 9 d SEM
a* Control 4.69a'z 5.59a,yz 5.82a,yz 5.90a,yz 6.42a,yz 8.70a'x 7.01a,xy 1.22
1% SMS 5.38ax 5.79ax 6.88ax 5.14ax 5.70ax 5.64b'x 5.82ab,x 1.23
2% SMS 6.23ax 5.63a'x 6.29ax 5.31 a,x 5.56a,x 5.09b,x 5.47abx 1.24
3% SMS 5.29a,xy 4.98a,xy 5.05a,xy 5.89ax 4.79a,xy 4.12b,y 4.41b,xy 0.97
4% SMS 5.52ax 4.96a,xy 6.21a,x 5.70a,x 5.04a,xy 4.73b,xy 3.94b,y 0.96
SEM 0.98 0.83 1.24 1.14 1.12 1.15 1.38
a-b Means in same column with different superscripts differ significantly (P < 0.05);
x-y Means in same row with different superscripts differ significantly (P < 0.05); n = 16 values per mean;
SMS = Sodium metasilicate; SEM = Standard error of the mean.


116









Table 4-30. Mean objective raw meat color b* values for boneless and skinless broiler chicken breast meat marinated
with sodium metasilicate and stored at 4C for 9 days
Storage time
Attribute Treatment 0 d 1 d 3 d 5 d 6 d 7 d 9 d SEM
b* Control 18.97az 22.40a,yz 24.62a,y 25.36a,y 26.74a,y 33.35ax 27.22a,y 3.19
1% SMS 19.95az 20.71ab,yz 24.16a'xyz 22.95ab,yz 24.42abxyz 29.46abx 25.96a'xy 3.40
2% SMS 20.06az 19.42b,z 21.95a'xyz 22.28abxyz 21.12bc,yz 26.31ab,x 26.08a,xy 3.19
3% SMS 19.16a,xy 16.91c,y 17.97b'xy 21.06bc,xy 18.43cdxy 22.74b,x 22.07ax 2.93
4% SMS 17.11a,xy 14.88C,y 17.81b,xy 17.90c,xy 16.77dxy 20.62b,x 21.39ax 3.12
SEM 2.54 1.47 2.61 2.48 2.36 5.54 3.54
a-b Means in same column with different superscripts differ significantly (P < 0.05);
x-z Means in same row with different superscripts differ significantly (P < 0.05); n = 16 values per mean;
SMS = Sodium metasilicate; SEM = Standard error of the mean.









Table 4-31. Mean cooked meat color for boneless and skinless broiler chicken breast
meat marinated with sodium metasilicate and stored at 40C for 6 days
Storage time


Attribute
L*


Treatment
Control
1% SMS
2% SMS
3% SMS
4% SMS
SEM


Control
1% SMS
2% SMS
3% SMS
4% SMS
SEM


Control
1% SMS
2% SMS
3% SMS
4% SMS
SEM


a-c Means in same column with different superscripts differ significantly (P < 0.05);
x-z Means in same row with different superscripts differ significantly (P < 0.05);
On trial II, only 3% and 4% treatments were not spoiled on 5 d and 6 d;
n = 24 values per mean;
SMS = Sodium metasilicate; SEM = Standard error of the mean.


118


0d
81.29ax
82.00ax
79.33ab,x
79.58ab,x
77.73b,y
2.18


1.78b,yz
1.96b,x
2.55ab,x
2.89a,x
3.00a,x
0.58


17.61b,y
19.02bx
21.71a,x
21.51ax
21.88ax
1.59


1 d
82.42ax
81.98ax
80.58b,x
80.25bx
80.11 b,xy
0.92


2.25a,yz
2.09a,x
2.03a,x
2.10a'y
2.13ax
0.46


18.45a,y
17.93ax
19.43a,xy
18.28a,yz
19.47a,yz
1.24


3d
77.21a,x
80.47a,xy
80.70a,x
80.57a,x
79.84a,xy
4.70


1.74bz
2.06ab,x
2.30ab,x
2.31 ab,xy
2.59a,x
0.42


18.09a,y
18.65ax
19.13a'xy
19.40a,y
20.06a,y
1.48


5d
76.79b,x
78.09ab,y
79.13ab,x
81.08ax
79.09b,xy
1.34


3.72a,x
2.66a,x
2.84a,x
1.76a,y
2.16ax
0.45


20.73a,x
18.89bx
19.91 ab,xy
19.80ab,xy
20.70a,xy
0.68


6d
78.66ax
79.65a'xy
78.90ax
81.34ax
80.80ax
1.84


2.76a,y
3.00a,x
2.69a,x
1.83a,y
2.30a,x
0.55


18.08a,y
18.61ax
18.76a,y
17.07az
18.16az
1.25


SEM
5.17
1.70
1.68
2.21
1.49




0.51
0.55
0.44
0.44
0.53



1.14
1.84
1.32
1.33
1.00









Table 4-32. Mean Warner-Bratzler shear force for boneless and skinless broiler chicken breast meat marinated with
sodium metasilicate and stored at 4C for 6 days


Storage time
Attribute Treatment 0 d 1 d 3 d 15 d 16 d SEM
Warner-Bratzler shear force, Kg Control 2.08ay 2.03b,y 1.95a,y 1.82a,y 2.81 a,x 0.27
1% SMS 2.17a,xy 2.59a,xy 2.42a,xy 1.96a,y 2.86ax 0.37
2% SMS 2.21a,xy 2.66a,x 2.31a,xy 1.85a,y 2.36a,xy 0.29
3% SMS 2.13ax 2.54ax 2.34ax 2.04ax 2.80ax 0.57
4% SMS 2.25ax 2.15b'x 2.28ax 2.20ax 2.26ax 0.30
SEM 0.29 0.20 0.29 0.40 0.73


Means in same column with different superscripts differ significantly (P < 0.05);
x-y Means in same row with different superscripts differ significantly (P < 0.05); n = 4 v
1on trial II, only 3% and 4% treatments were not spoiled on 5 d and 6 d;
SMS = Sodium metasilicate; SEM = Standard error of the mean.


values per mean;


119









Table 4-33. Panelist rating for juiciness and chicken flavor intensity for boneless and skinless broiler chicken breast meat
marinated with sodium metasilicate and stored at 40C for 6 days
Storage time
Attribute Treatment 0 d 1 d 3 d 15 d 16 d SEM
Juiciness Control 4.60b,y 5.38a,xy 5.92ax 5.09a,xy 5.50a,xy 0.65
1% SMS 4.11b,y 4.69a,xy 6.03ax 5.34a,xy 5.63a,xy 0.80
2% SMS 4.51 b,y 5.02a,xy 6.13ax 6.04ax 5.50a,xy 0.67
3% SMS 5.99ax 5.98ax 6.40ax 4.95ax 5.60ax 1.05
4% SMS 5.69ax 5.08ax 5.92ax 6.36ax 6.50ax 0.99
SEM 0.65 0.96 0.76 1.13 0.90

Chicken Flavor Control 5.08abx 4.23ax 4.90ax 5.34ax 5.00ax 0.98
1% SMS 3.90b,y 4.88a,xy 5.26a,xy 5.79ax 5.13a,xy 0.85
2% SMS 4.53abx 4.58ax 5.35ax 4.59ax 4.75ax 0.88
3% SMS 6.04ax 5.88ax 5.97ax 5.21ax 4.68a,x 1.33
4% SMS 5.20ab,y 5.19a,y 5.53a,xy 6.63a'x 6.29a,xy 1.09
SEM 0.42 1.15 0.80 1.10 1.23


a-Means in same column with different superscripts differ significantly
x-y means in same row with different superscripts differ significantly (P


(P < 0.05);
< 0.05); n = 20 values per mean;


Sensory scale: Eight-point sensory scale for juiciness, chicken flavor where 8 = extremely juicy/intense, 7 = very
juicy/intense, 6 = moderately juicy/intense, 5 = slightly juicy/intense, 4 = slightly dry/bland, 3 = moderately dry/bland, 2 =
very dry/bland, 1 = extremely dry/bland.
1 on trial II, only 3% and 4% treatments were not spoiled on 5 d and 6 d;
SMS = Sodium metasilicate; SEM = Standard error of the mean.


120









Table 4-34. Panelist rating for tenderness and off-flavor for boneless and skinless broiler chicken breast meat marinated
with sodium metasilicate and stored at 4C for 6 days
Storage time
Attribute Treatment 0 d 1 d 3 d 15 d 16 d SEM
Tenderness Control 5.61ax 5.48b,x 6.46a'x 7.54a'x 7.13ax 1.40
1% SMS 7.84ax 5.81ab,x 6.08ax 7.67a'x 7.13ax 1.33
2% SMS 7.16ax 7.33ax 7.49ax 7.67a'x 7.13ax 0.33
3% SMS 6.93a,xy 7.19abx 7.24a'x 6.31a,xy 5.71a,y 0.78
4% SMS 6.38ax 6.15abx 6.65ax 6.71a'x 6.40ax 0.77
SEM 1.00 1.08 0.98 0.76 0.94

Off-Flavor Control 5.29a,y 5.79ax 5.94a'x 5.25b'y 6.00ax 0.29
1% SMS 5.75ax 5.86ax 5.69ax 5.88ax 5.75abx 0.34
2% SMS 5.70ax 5.73abx 5.81ax 5.59abx 5.38b'x 0.22
3% SMS 5.63ax 5.94ax 5.82ax 5.83ax 5.78abx 0.29
4% SMS 5.81a'x 5.52b'x 5.55ax 5.82ax 5.81ab,x 0.27
SEM 0.36 0.17 0.25 0.27 0.27
a-b Means in same column with different superscripts differ significantly (P < 0.05);
x-y Means in same row with different superscripts differ significantly (P < 0.05); n = 20 values per mean;
Sensory scale: Eight-point sensory scale for tenderness where 8 = extremely tender, 7 = very tender, 6 = moderately
tender, 5 = slightly tender, 4 = slightly tough, 3 = moderately tough, 2 = very tough, 1 = extremely tough. A six-point scale
for off-flavor where 6 = none detected, 5 = threshold, barely detected, 4 = slight off-flavor, 3 = moderate off-flavor, 2 =
strong off-flavor, 1 = extreme off-flavor;
1 on trial II, only 3% and 4% treatments were not spoiled on 5 d and 6 d;
SMS = Sodium metasilicate; SEM = Standard error of the mean.









CHAPTER 5
SUMMARY AND CONCLUSION

Results from this study suggested that the fillets treated with sodium metasilicate

had higher marination yield, when compared to control treatment. The pH values of

meat after marination with sodium metasilicate increased, and the values of pH were

close to neutral point (pH = 7). The water holding capacity measured with sodium

chloride for fillets were similar among all treatments through 9 days storage. The water-

holding capacity measured with distilled water for fillets treated with 3% and 4% sodium

metasilicate were slightly higher than control fillets. The purge loss percentages for all

treatments were similar through 7 days storage. The fillets treated with 3% sodium

metasilicate had higher cooking yield than control fillets. The fillets treated with 3% and

4% sodium metasilicate had one additional day of shelf life, when compared to control

fillets. Fillets treated with 3% sodium metasilicate were darker during the first 3 days of

storage, when compared to control fillets. But after day 3, the fillets treated with 3%

sodium metasilicate were lighter than control fillets. The fillets treated with 3% and 4%

sodium metasilicate were less yellow than control fillets, and had similar red color for all

treatments. Based on the panelist responses, the fillets treated with 3% and 4% sodium

metasilicate were juicier than control fillets, and no significant differences were

observed among all treatments for tenderness, chicken flavor intensity and off-flavor

characteristics. No significantly differences were observed for shear force values for all

treatments.

The results revealed that USDA approved levels were not effective to improve the

meat quality and shelf life. The elevated levels of 3% and 4% sodium metasilicate could

extend shelf life to two additional days. The disadvantages of sodium metasilicate


122









treatments included discoloration (darken) of the fillets, and provided suitable pH values

for microbial growth. More work should be conducted to investigate the utilization of

sodium metasilicate in hurdle technology to improve the meat quality and shelf life.

Hurdle technology would include using sodium metasilicate in combination with other

antimicrobials and at higher concentration levels (i.e.) for sodium metasilicate greater

than approved level of 2% in marinade solutions.


123









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BIOGRAPHICAL SKETCH

Huisuo Huang was born in Hebei province in China, in 1981. She received her

Bachelor of Science degree in Food Science and Technology with honors from Hebei

Normal University of Science & Technology, Qinhuangdao, China in 2005. She worked

in Hebei Food Additive Co., LTD. for one and half years after graduated. She started

her master's degree in 2009 in Food Science and Human Nutrition at the University of

Florida. She conducted her master's research in the Department of Animal Science

since August 2009. Her current concentration was Food Safety and Food Microbiology.

She earned her Master of Science degree in August 2010. Upon graduation, Huisuo

plans to continue doing research in food industries or academy institutes. Her ultimate

goal is to accelerate the exchanges and cooperation between China and the United

States about economic and trade related with food.


130





PAGE 1

1 THE EFFECTS OF SODIUM METASILICATE ON ANTIMICROBIAL, SENSORY, PHYSICAL AND CHEMICAL CHARACTERISTICS OF FRESH COMMERCIAL CHICKEN BREAST MEAT STORED AT FOUR DEGREES CELSIUS FOR NINE DAYS By HUISUO HUANG A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2010

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2 2010 Huisuo Huang

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3 T o my husband, Y ongqiang Yang ; my son, Allen Y ang; and my parents, Fuxing Huang and X iaoyu W ang.

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4 ACKNOWLEDGMENTS I would like to convey my gratitude to Dr. Sally K. Williams my major professor, for her supervision, advice, and guidance from the very early stage of this research as well as giving me extraordinary experiences throughout the work. She provided her unflinching encouragement and support in various ways. Appreciation is also expressed to my committee members, Dr. Amarat Simonne, Dr. Charles A Sims, for their advice and support during this project. Their t ruly scientist intuition exceptionally inspire and enrich my growth as a student, a researcher and a scientist I appreciate them more than they know. I would like to express special thanks and appreciation to Dr. Gary Eugene Rodrick for giving me the opportunity to continue my career. I would like to thank Noufoh Djeri for technical assistances and abundantly help during the work. I would like to thank her for being the first person who taught me how to work in this project. I also would like to deeply i mpress my appre ciation to Frank Robbins Jr. for his assistance and encouragement. I would like to express gratitude to my husband. This research project would not have been done without his support. Special thanks to my son, Allen, for his spiritual suppor t and providing the huge motivation. I would like to express my love and gratitude to my parents and parents in laws for their understanding and endless love through the duration of this project. I would like to thank my sisters for their love and support. Finally, I would like to thank everybody who was important to the successful realization of thesis, as well as expressing my apology that I could not mention personally one by one.

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5 TABLE OF CONTENTS ACKNOWLEDGMENTS .................................................................................................. 4 Page TABLE OF CONTENTS .................................................................................................. 5 LIST OF TABLES ............................................................................................................ 8 LIST OF FIGURES ........................................................................................................ 11 ABSTRACT ................................................................................................................... 12 CHAPTER 1 INTRODUCTION .................................................................................................... 14 2 LITERATURE REVIEW .......................................................................................... 17 Possible Contamination Sources during Broiler Chicken Breast Processing and Control Strategies ................................................................................................ 17 Sanitary Conditions .......................................................................................... 17 Primary Processing of Broiler Chicken Breast .................................................. 19 Factors that Affect Microbial Growth on Fresh Broiler Chicken Breast Meat .......... 25 Intrinsic Factors ................................................................................................ 25 Extrinsic Factors ............................................................................................... 27 Spoilage and Pathogenic Microorganisms Associated with Fresh Broiler Chicken Meat ....................................................................................................... 28 Spoilage Organisms Associated with Raw Chicken Breast Meat ..................... 28 Pathogenic Organism s Associated with Raw Poultry Breast Meat. .................. 30 Salmonella ................................................................................................. 31 Campylobacter ........................................................................................... 33 Antimicrobials Used in Chicken Breast Meat to Control Pathogenic and Spoilage Bacteria ................................................................................................ 34 Chloride ............................................................................................................ 37 Organic Acids and Their Salts .......................................................................... 38 Sodium Tripolyphosphate ................................................................................. 41 Sodium Metasilicate ......................................................................................... 42 3 MATERIALS AND METHODS ................................................................................ 44 Phase I. Preliminary Study: Application Method and Evaluation of Sodium Metasilicate at Approved Level for Poultry Meat .................................................. 44 Sample Preparation .......................................................................................... 44 Sample Treatment and Marination Yield .......................................................... 44 Experiment one .......................................................................................... 44 Experiment two .......................................................................................... 45

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6 pH Analysis ...................................................................................................... 46 Cooking Yield Analyses .................................................................................... 46 Experiment one: Grill reconstitution method .............................................. 46 Experiment two: Oven reconstitution method ............................................. 47 Microbiological Analyses .................................................................................. 47 Experiment one .......................................................................................... 47 Experiment two .......................................................................................... 48 Objective Color Measurement .......................................................................... 49 Warner Bratzler Shear Force Analysis ............................................................. 49 Sensory Evaluation Analyses ........................................................................... 50 Experiment one: Grilled fillets .................................................................... 50 Experiment two: Baked fillets ..................................................................... 50 Phase II. Prelimi nary Study: Determination of the Effectiveness of Sodium Metasilicate at Approved and Elevated Levels and a Shelf Life Study. ............... 52 Water Holding Capacity Analyses .................................................................... 53 Phase III. Investigation of the Effectiveness of Sodium Metasilicate at the USDA Approved and Elevated Level s on Antimicrobial, Sensory, Chemical and Physical Characteristics of Fresh Chicken Breast Meat Stored at 4C for 9 Days .................................................................................................................... 54 Sample Preparation .......................................................................................... 54 Sample Treatment and Marination Yield .......................................................... 54 pH Analysis ...................................................................................................... 55 Water Holding Capacity Analyses .................................................................... 56 Purge Loss Analysis ......................................................................................... 57 Cooking Yield Analysis ..................................................................................... 58 Microbiological Analysis ................................................................................... 58 Objective Color Measurement .......................................................................... 59 Warner Bratzler Shear Force Analysis ............................................................. 59 Sensory Evaluation .......................................................................................... 60 Statistical Analysis ............................................................................................ 61 4 RESULTS AND DISCUSSION ............................................................................... 62 Phase I. Preliminary Study: Application Method and Evaluation of Sodium Metasilicate at Approved Leve l for Poultry Meat .................................................. 62 Experiment 1 .................................................................................................... 62 Marination yield analysis ............................................................................ 62 pH and cooking yield analyses ................................................................... 62 Microbiological analysis ............................................................................. 62 Objective color measurement .................................................................... 63 Sensory evaluation and warner bratzler shear force analyses ................... 64 Experiment 2 .................................................................................................... 64 Marination yield analysis ............................................................................ 64 pH analysis ................................................................................................ 64 Cooking yield analysis ............................................................................... 65 Microbiological analysis ............................................................................. 65 Objective color measurement .................................................................... 65

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7 Warner bratzler shear force analysis ......................................................... 66 Sensory evaluation .................................................................................... 66 Phase II. Preliminary Study: Determination of the Effectiveness of Sodium Metasilicate at USDA Approved and Elevated Levels in a Shelf Life Study ........ 67 Marination Yield Analysis ................................................................................. 67 pH Analysis ...................................................................................................... 68 Water Holding Capacity Analyses .................................................................... 68 Water holding capacity with sodium chloride ............................................. 68 Water holding capacity with distilled water. ............................................... 69 Cooking Yield Analysis ..................................................................................... 69 Microbiological Analysis ................................................................................... 70 Objective Color Measurement .......................................................................... 71 Raw fillet color ............................................................................................ 71 Cooked fillet color ...................................................................................... 72 Warner Bratzler Shear Force Analysis ............................................................. 73 Sensory Evaluation .......................................................................................... 73 Phase III. Investigation the Effectiveness of Sodium Metasilicate at the USDA Appr oved Level and Elevated Level s on Antimicrobial, Sensory, Chemical and Physical Characteristics of Fresh Chicken Breast Meat and Stored at 4C for 9 Days ............................................................................................................ 74 Marination yield Analysis .................................................................................. 74 pH Analysis ...................................................................................................... 74 Water Holding Capacity Analyses .................................................................... 75 Water holding capacity with sodium chloride. ............................................ 75 Water holding capacity with distilled water. ............................................... 75 Purge Loss Analysis ......................................................................................... 76 Cooking Yield Analysis ..................................................................................... 76 Microbiological Analysis ................................................................................... 76 Objective Color Measurement .......................................................................... 77 Raw fillet color. ........................................................................................... 77 Cooked fillet color ...................................................................................... 79 Warner Bratzler Shear Force Analysis ............................................................. 80 Sensory Evaluation .......................................................................................... 81 Juiciness .................................................................................................... 81 Chicken flavor in tensity .............................................................................. 81 Tenderness ................................................................................................ 81 Off flavor .................................................................................................... 82 5 SUMMARY AND CONCLUSION .......................................................................... 122 LIST OF REFERENCES ............................................................................................. 124 BIOGRAPHICAL SKETCH .......................................................................................... 130

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8 LIST OF TABLES Table p age 4 1 Total psychrotrophic counts for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C on day 0 ............... 85 4 2 Meat color measurement for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C on day 0 ............... 85 4 3 Sensory evaluation and War ner Bratzler shear force for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C on day 0 ........................................................................................ 86 4 4 pH measurement for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 6 days ...................... 87 4 5 Total psychrotrophic counts for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 6 days ............. 88 4 6 Objective raw meat color for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 3 days ............. 89 4 7 Objective cooked meat color for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 3 days ............. 90 4 8 Warner Bratzler shear force for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 3 days ............. 91 4 9 Panelist rating for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 3 days ...................... 92 4 10 pH measurement for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days ...................... 94 4 11 Water holding capacity percentages for boneless and skinless broiler chicken breast meat marinated w ith sodium metasilicate and stored at 4C for 9 days: WHC with sodium chloride ................................................................................. 96 4 12 Water holding capacity percentages for boneless and skinless broiler chicken breast meat marinated with s odium metasilicate and stored at 4C for 9 days: WHC with distilled water only ............................................................................. 97 4 13 Total psychrotrophic counts for boneless and skinless broiler chicken breast meat marinated with sodium m etasilicate and stored at 4C for 9 days ............. 99 4 1 4 Objective raw meat color L* values on boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C f or 9 days 100

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9 4 15 Objective raw meat color a* values for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days 101 4 16 Objective raw meat color b* values for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days 102 4 17 Objective cooked meat color L* values for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days .......................................................................................................... 103 4 18 Objective cooked meat color a* values for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days .......................................................................................................... 104 4 19 Objective raw meat color b* val ues for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days 105 4 20 Warner Bratzler shear force for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days ........... 106 4 21 Panelist rating for juiciness and chicken flavor intensity for boneless and skinless broiler chick en breast meat marinated with sodium metasilicate and stored at 4C for 9 days .................................................................................... 107 4 22 Panelist rating for tenderness and off flavor for boneless and skinless broiler chicken breast meat mari nated with sodium metasilicate and stored at 4C for 9 days .......................................................................................................... 108 4 23 Mean pH measurements for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days ........... 110 4 24 Mean water holding capacity percentages for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days: WHC with sodium chloride and distilled water ................................ 111 4 25 Mean purge loss percentages for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days 112 4 26 Mean cooking yield percentages for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 6 days 113 4 27 Mean total psychrotrophic counts for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days 114 4 28 Mean objective raw meat color L* values for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days .......................................................................................................... 115

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10 4 29 Mean objective raw meat color a* values for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days .......................................................................................................... 116 4 30 Mean objective raw meat color b* values for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days .......................................................................................................... 117 4 31 Mean cooked meat color for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 6 days ........... 118 4 32 Mean Warner Bratzler shear force for boneless and skinless broiler chicken breast meat marinated with sodium m etasilicate and stored at 4C for 6 days 119 4 33 Panelist rating for juiciness and chicken flavor intensity for boneless and skinless broiler chicken breast meat marinated with sodium metasil icate and stored at 4C for 6 days .................................................................................... 120 4 34 Panelist rating for tenderness and off flavor for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 6 days .......................................................................................................... 121

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11 LIST OF FIGURES Figure 4 1 Marination yield percentages for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C on day 0 ............... 83 p age 4 2 pH value for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C on day 0 ........................................ 83 4 3 pH of marinade solutions for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C on day 0 ............... 84 4 4 Cooking yield percentages for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C on day 0 ............... 84 4 5 Marination yield percentages for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 6 days ............. 86 4 6 Cooking yield percentages for boneless and skinless broiler chick en breast meat marinated with sodium metasilicate and stored at 4C for 6 days ............. 87 4 7 Marination yield percentages for boneless and skinless broiler chicken breast meat marinated with sodium m etasilicate and stored at 4C for 9 days ............. 93 4 8 Marinade solution of pH for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C on day 0 ............... 95 4 9 Cooking yield percentages for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days ............. 98 4 10 Marination yield percentages for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days ........... 109

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12 Abstract of Thesis Presented to the Graduat e School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science THE EFFECTS OF SODIUM METASILICATE ON ANTIMICROBIAL, SENSORY, PHYSICAL AND CHEMICAL CHARACTERISTICS OF FRESH COMMERCIAL CHICKEN BREAST MEAT STORED AT FOUR DEGREES CELSIUS FOR NINE DAYS By Huisuo Huang August 2010 Chair : Sally K. Williams Major: Animal Sciences Marination for meat quality enhancement is an increasingly popular trend in the meat industry. The purpose of this study was to investigate the effectiveness of sodium metasilicate at the USDA approved level and at elevated level s with respect to a ntimicrobial effect sensory, chemical and physical characteristics of fresh chicken breast meat stored at 4C for 9 day s. Breast fillets were marin ated in a vacuum tumbler (172.32 kPa) with tap water and 1%, 2%, 3% or 4% sodium metasilicate for 20 minutes. Marination yield, pH, water holding capacity, purge loss, cooking yield, total psychrotrophic counts, raw meat color, cooked meat color and texture were evaluated in this study. Sensory evaluation included j ui ciness, chicken flavor intensity, tenderness and off flavor using a trained sensory panel The evaluation of treated raw fillets for 9 days storage revealed that, fi llets treated with 3% and 4% sodium metasilicate had higher (P < 0.05) pH and two additional days of shelf life, when compared to control fillets. The cooking yield percentage for fillets treated with 3% sodium metasilicate were higher (P < 0.05), when com pared to control fillets. The control fillets and fillets treated with sodium metasilicate were similar (P > 0.05) for purge loss, cooked meat color,

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13 instrumental texture, sensory evaluation, and water holding capacity. When the sodium metasilicate solutions elevated levels up to 4%, the fillets treated with 3% and 4% sodium metasilicate could result in discoloration during the first 3 days of storage, when compared to control fillets. These results suggested that sodium metasilicate at USDA approved levels up to 2% could not sufficiently extend shelf life of raw chicken breast meat. If it were employed in practice, combi nation with other antimicrobial approaches or increasing the sodium metasilicate levels might be applicable to control microbial growth and extend shelf life.

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14 CHAPTER 1 INTRODUCTION Poultry meat and products are important components of diets in the United States. The annual per capita consumption continues to increase each year and has for decades. Chickens contribute seventy to 80% of the annual consumption, while turkeys contribute to only 19% (International Commission on Microbiological Specification for Foods ICMSF, 1998). Total meat per capita consumption (red meat and poultry) in 2007 was 100.7 kilograms. Of these meat, 53.2 kilogram s were contributed by red meat, whereas, 47.5 kilograms was from poultry. Meat consumption has significantly increased since 1975, where only 21.5 kilograms poult ry meat was consumed per capita (Laux, 2009; USDA, 2009). Consumers prefer purchasing skinles s or boneless poultry parts and further processed products instead of the whole carcasses. For example, approximately 90% of poultry meat in the United States is sold as parts or further processed products (Young and Lyon, 1997). Consumers are especially i nterested in chicken parts due to the convenience and nutritional value, such as chicken breast meat (Seabra et al., 2001). Broiler breast meat is considered the premium part in the United States (Saha et al., 2009). Due to the uneven geographic distributi on of poultry producers in the USA, most poultry plants are located in the southeast. Therefore, raw poultry products require transportation from the southeast of the U.S. to other districts in order to provide fresh poultry (Russell, 1998; Angella, 1999). A major problem with extensive transporting of raw poultry is that the natural properties of chicken provide an excellent substrate for microbial growth and raw poultry meat is a highly perishable commodity (Russell, 1998; White, 2000; Mead, 2004). The sa fety of poultry directly impacts the public health and

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15 economy. Therefore, the requiring intervention strategies that could prolong shelf life of poultry and poultry products are of major concern to the government, corporation and consumers (Johny et al., 2008). More than 1.4 million cases of nontyphoid salmonellosis and 2.4 million cases of Campylobacter infection were reported annually in the United States. The money spent for Salmonella and Campylobacter related illnesses associated with poultry were approximately $ 64 million to $ 114.6 million, and $ 362 million to $ 699 million, respectively (Altekruse et al., 1999; Johny et al., 2008). Inadequate cooking, time and temperature abuse, and cross contamination obtained from raw poultry products are major contributors to the primary reasons of foodborne illness outbreak. Cunningham and Cox (1987) stressed that anything that contacts a single bird might lead to contamination and anything that contacts more than one bird might have crosscontamination. Ja y ( 1992) reported that intrinsic parameters and extrinsic parameters associated with poultry could determine microbial lo ad and types. Any technologies that could modify these factors could extend shelf life of poultry products. Numerous approaches that have been investigated can be divided into chemical, physical and a combination of chemical and physical methods (Bolder, 1997) Each step in poultry processing, from farm to ready to cook product may be factors that influence the microbial load and types. Various antimicrobial chemicals have been employed into the poultry processing line. For instance, organic acids are used to wash, rinse and spray to clean carcasses and to reduce numbers of microorganisms. Other antimicrobial chemicals such as alternativ e chlorine and phosphate using in scalding water and spraying also have been

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16 investigated to affect the shelf life and poultry quality. A nother process that may be applied to introduce chemical anti microbials is called marination which included vacuum tumb ling, injection or combination methods In this literature review, the source of contamination during poultry proces sing control methods to reduce microbial load; factors that determine the micr obial quality of poultry meat; the microorganisms associated with poultry; mechanisms of action and effect of chlorine, organic acids and salts acidified sodium chlorite, and sodium tripolyphosphate on sensory characteristics and the functional possibilities of applying sodium metasilicate, which shares some similarities with sodium tripolyphosphate, will be discussed.

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17 CHAPTER 2 LITERATURE REVIEW Possible Contamination Sources during Broiler Chicken Breast Processing and Control Strategies Sanitary Conditions The numbers and types of microorganisms present in fres h chicken carcasses mainly contribute to four sources: (1) original flora of microorganisms in the raw chicken; (2) sanitary conditions around products such as wall surfaces, equipment, transfer machine, air and handlers; (3) control measures utilized duri ng processing; and (4) sanitary conditions during packaging, handling and storage (Pearson and Dutson, 1994; Mead, 2007). Initial contamination generally results from live birds even healthy chickens. A healthy live bird carries several kinds of microorganisms on its skin, feathers, and in its intestinal tract. The microbial population of poultry carcasses could be generally divided into three types: the natural flora of skin; the transient flora, attached on the skin and feathers, which could be easily removed during slaughter processing; and obtained organisms during processing, it is generally called cross contamination. Carcasses may be contaminated due to contact with equipment, tools, hands or gloves of workers and contaminated birds (Cunningham and C ox, 1987; ICMSF, 1998). However, most natural floras have no detrimental effect on consumers. But if control measurements are not used appropriately or efficiently, natural floras will decrease product quality (Russell, 1997). The finished products that c ontained amounts and types of organisms were dependent on processing practices (Pearson and Dutson, 1994). Some microorganisms can be transmitted from the intestines of parent chicken to its offspring. Live healthy birds may get infected by contacting wit h the contaminated eggs, net materials and

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18 incubators. Additionally, air current may spread microorganisms among hatcheries (ICMSF, 1998). B esides, the healthy chicken may be contaminated by the feeding food and drinking water. Feeding food may contain ani mal protein ingredients and drinking water may be contaminated by dust, litter, feathers, feet and feces. R odents and cockroaches may spread microorganisms within the poultry flock. Also w orkers may spread pathogens through their shoes within flocks as w ell (ICMSF, 1998). Hence, live birds may arrive at the processing plant with various bacteria from both the external and internal part of chicken bodies ( Bolder 1997; Russell, 1997). T here are some possibilities that any of these microorganisms could be t he sources of contamination of the final products (Mead, 2004). Spoilage bacteria, mainly Achromobacter (Acinetobacter), Corynebacterium and Flavobacterium, were detected in the respiratory systems of fresh broiler chickens. These microorganisms were detected on feathers, feet of live chickens, water and feed supply, and equipment in the processing plant (Russell, 1997; Russell, 1998). However, the number of spoilage organism s significantly declined after scalding. Cunningham and Cox (1987) reported that P seudomonas, primarily detected in eviscerated spoiled chicken, could not be isolated in the respiratory system or in the intestinal tract after washing. The potential pathogens derived from the intestine of live chickens, which Salmonella spp., Campylobact er spp., Listeria spp., E. coli O157:H7 and Staphylococcus are of concern to processors (Bolder, 1997). If the processing plant practices do not efficiently manage the spread of microorganisms, then final meat quality and shelf life could be significantly affected (Russell, 1997). The presence of bacteria and spreading routes depend on plant hygiene conditions during harvest,

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19 slaughter, processing, storage, distribution and preparation (Russell, 1997; Mead, 2004). Primary Processing of Broiler Chicken Br east Mead (2004) concluded that the processing flow, which involved from live broiler chicken to ready to cook chicken products, could be classified into four steps. The first step includes receiving and hanging the live broilers. The s econd step is considered the dirty processing (Mead, 2004), which includes stunning, slaughter, bleeding, and defeathering (scalding, picking and washing). The elements of the third step are evisceration (viscera removal, offal) and carcass washing. The fourth step involves chilling, grading, packaging, shipping, and may include further processing (Cunningham and Cox, 1987; ICMSF, 1998; Mead, 2004). Mead (2004) pointed out that the types and population of microorganisms on t he final chicken products were chiefly dependent on the microbial state of the live broiler chicken. Since the plant producers cannot assure eradication of all pathogens during processing, it is important to control the pathogenic organisms on the farm. Vaccinating the birds and maintaining a clean environm ent are regarded as the best strategies to reduce the opportunity for vertical contamination of pathogenic microorganisms. The principal genera of microorganisms could be detected in the intestinal system and respiratory system of the healthy broiler chick en. In the intestinal system, the organisms include Lactobacillus, Corynebacterium Escherichia coli, Streptococcus faecalis, and Clostridium perfringens The respiratory system of healthy birds contains Streptococcus, Staphylococcus, Corynebacterium, Lact obacillus, Escherichia, and Bacillus. The psychrotrophic bacteria that could be found on the feet, skin, and feathers of live chicken are Flavobacterium, Achromobacter, and Corynebacterium However,

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20 after scalding, the psychrotrophic organisms would be dramatically diminished. Pseudomonas is not commonly detected in scalding water since it does not exist on the live chicken (Cunningham and Cox, 1987) After unloading birds to the processing plant, E coli numbers were higher on the chicken breast surface com pared with that prior to loading (Mead, 1989). Marin and Lainez (2009) reported that the colonization of Salmonella after transportation to the abattoirs was strikingly amplified. Some researchers concluded that stress during loading and transportation may accelerate the spread of bacteria (Mead, 1989; Richardson and Mead, 1999). During hanging chicken on the shackle, a majority of chicken s may struggle and flap their wings causing dust, feathers and litter to fall down, which may lead to scatter dust and s pread microorganisms. Mead (1989) also reported that Salmonellas and Staphylococcus aureus were easily detected in the air of the unloading compartment. So the effective method preventing spreading bacteria was to separate the unloading truck from the other following processing. Traditional stunning birds with electrical shock and then bleeding carcasses have been reported to have an insignificantly influence on the final product regarding microbial quality (ICMSF 1998). After stunning, the neck cutting machines, with one or two blades commonly used in the poultry industry, will detach the carotid vein and artery on each side of the neck. The advantage of this method is to remove the esophagus and trachea during evisceration processing (Mead, 2004). The next step is defeathering which contains scalding, picking and washing. Methods of scalding include hot water immersion, hot water spray, steam, and combination of hot water spray and defeathering (ICMSF, 1998). In general, hot water immersion scalding is the most

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21 common in industry. T he time and temperature of scalding water was determined by the appearance of the required product and chilling method (ICMSF, 1998). For example, turkeys are usually hard scalded to mai n tain the white skin appearance. In industry, chickens are soft scald ed when meat is sold fresh due to the unappealing color developed when using hard scald. The primary purpose of scalding is to readil y remove feathers when plucking, but the microbial effect cannot be ignored during scalding process. After scalding, microorganisms are detected in the water tank. These microorganisms come from skin, feathers, and intestinal tracts of birds. Several bacteria could be isolated from the scalding water or from the carcass immediately after scalding, such as Clostridium, Micrococcus, Proteus, Pseudomonas, Salmonella, Staphylococcus, and Streptococcus (ICMSF, 1998). However Mead (2007) stated that Salmonella was not frequently isolated from scalding water, and Pseudomonas was easily inactivated at any scalding temperature. When scalding water was maintained at 58C to 60C, it was not a major source of contamination (Pearson and Dutson, 1994). Furthermore, experimental evidence also proved the theory that a scalding water temperature of more than 60C could reduce a larger number of bacteria than a lower temperature (Cunningham and Cox, 1987; Mead, 2004). ICMSF (1998) reported that salmonellae were not detected on chicken carcasses after scalding at 60 C for 200 seconds, but at 55 C for 105 seconds. Brotsky and B ender (1991) stressed that the external and internal Salmonella of carcasses could be reduced by adjusting the pH value of scalding hot water to approximately 9.0. Cross contamination can be reduced by adjusting the scalding water temperature, scalding time and water pH (ICMSF, 1998; Mead, 2004).

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22 Subsequent to the scalding step, psychrotrophic bacteria were dramatically diminished. Pseudomonades were not usually detected in scald water (Cunningham and Cox, 1987). Therefore, scalding was not the significant source of the contamination of spoilage microorganisms, nor the best step to control propagation of Campylobacter jejuni (ICMSF, 1998). Alternative interventions such as steam with hot water scalding and three tank systems with hyperchlorinat ion solution could control cross contamination. Nevertheless, it is not practical in industry because these methods could produce discoloration of carcasses (Mead, 2004; ICMSF, 1998; Davies and Board, 1992). In contrast, cross contamination was of most c oncern during the defeathering and evisceration processing (Pearson and Dutson, 1994). There are machines that employed rotating rubber fingers to release feathers from carcasses, however, if the rubber fingers fail to release the feathers, the feathers fr om the rubber fingers will harbor microorganisms and be difficult to clean. The rubber fingers deteriorate easily due to high line operating speed. Hence, the rubber fingers would become the source of spreading microbial to carcasses. In addition, aerobi c plate counts and staphylococcal counts, rather than psychrotrophic spoilage bacteria counts, were higher after d efeathering (ICMSF, 1998; Mead, 1989). Research reported that strains of Staphylococcus aureus attached to the machine became resistant to low concentrations of chlorine. A fterwards, bacteria became indigenous to the machines and were difficult to eliminate. The best method to control the contamination during defeathering and evisceration was cleaning with a higher level of chlorine before disinfecting, also frequently altering rubber fingers and preventing feathers from depositing into the

PAGE 23

23 machine. Furthermore, the infection of Salmonellae, Campylobacter and E.coli O157: H7 organisms spread from few carcasses to many carcasses in the early step of feathering processing. In later stages, microorganisms may penetrate into muscles and are hard to get rid of. Therefore, defeathering was the major step to cause carcass contamination (Mead, 1989). The population of microorganisms after defeathering co uld predict microbial load, and quality of poultry carcass to some degree (ICMSF, 1998). The third step included evisceration and washing the carcass. During evisceration, carcasses may become cross contaminated from the hands of workers, carcasses to equipment or tools, then to the rest of the carcasses (ICMSF, 1998; Russell, 1997). Mead (2004) demonstrated that psychrotrophic bacteria contamination could take place during evisceration because Pseudomonades could spread from gloves to carcasses. The psych rotrophic pathogens, like Listeria monocytogenes, could attach to the evisceration apparatus (Mead, 2004). Spraying carcasses with water after defeathering and evisceration could get rid of organic substances and microorganisms gained during evisceration. Spraying carcasses many times after evisceration could decrease population of Salmonella and Enterobacteriaceae compared to spraying carcasses a single time (ICMSF, 1998). Eviscerated poultry may carry a high population of Salmonella. Salmonella attached on the carcasses surface involved multiplication sequence, transmitted to equipment, hands or other surfaces. In spite of this, water spraying could eliminate Salmonella (Brotsky and Bender, 1991) and also could reduce aerobic plate counts, Enterobacteriace ae and coliform s by 50 to 90%, respectively (ICMSF, 1998). However, some Pseudomonas spp. may disperse among carcasses during spraying. Studies concluded that spraying carcasses with organic acid or

PAGE 24

24 chlorine did not inhibit the cross contamination, and it could not prolong the shelf life of fresh poultry meat (ICMSF, 1998), because the chlorine solutions immediately fell down from the carcasses, and this reduced the effectiveness of the chemical compounds (Mead, 2004; Northcutt et al., 2005). The forth st ep included chilling, grading, packaging and transporting, as well as pos sibility of further processing. After evisceration, chilling was a valuable step to slow the growth rate of spoilage microorganisms and to manipulate pathogenic microbial growth (ICMS F, 1998; Mead, 2004). Most pathogenic organisms cannot generally grow below 6C, but psychrotrophic bacteria could multiply at below 0C. Common chilling processes were air chilling (dry chilling), wet chilling and combination chilling. Which chilling method used depended on how the meat was sold. It may be sold as a whole carcass, portioned or deboned meat like chicken breast meat. Raw chicken breast meat was sold wet fresh or frozen; therefore, wet chilling processing would be used. If raw broiler chicken breast meat was chilled by air, the discoloration would appear and impair the meat quality. Meat without normal surface color could not be accepted by producers and consumers. For raw chicken meat, the most common wet chilling methods were water immersion chilling and spray chilling (ICMSF, 1998; Mead, 2004). After chilling processing, no further growth of mesophile organisms should be detected. However, a time delay in the transfer of carcasses to chill storage would tolerate growth of psychrotrophic organisms (Mead, 1989). Further cross contamination could be related to handling, incising whole carcasses, deboning and circumstances related to packaging.

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25 The long shelf life of meat can be determined by monitoring the growth of psychrotrophic microorganis ms. Therefore, keeping hygienic conditions of equipment, carrying out sanitation specifications, maintaining the appropriate storage temperature and properly holding of products were of great importance to assure the quality of the chicken breast (ICMSF, 1 998; Russell, 1998; Mead, 2004). Blackburn (2006) concluded that the current methods of controlling cross contamination of microorganisms in slaughterhouses, during processing and package were contingent upon fulfilling the hygienic standards of Good Manuf acturing Practices (GMP) at farms, Good Hygienic Practices (GHP), animal husbandry practices, and carrying out the HACCP system. Factors that Affect Microbial Growth on Fresh Broiler Chicken Breast Meat Intrinsic Factors Raw fresh broiler chicken meat pr ovides good substrate for bacteria growth due to the biological and chemical composition of chicken meat. Bacteria growth on broiler chicken is determined by inherent properties of chicken meat as well as external circumstances around chicken meat. Inherent parameters are moisture content, water activity or available water, pH or total acidity, oxidationreduction potential (Eh), nutrient content, and the biological structure of raw chicken (George, 1989; Michael et al., 2001). Temperature and gas conditions during storage and distribution are considered to be the key extrinsic factors that affect the shelf life of raw fresh chicken meat (Pearson and Dutson, 1994). The combination of intrinsic factors and extrinsic factors could determine the shelf life and quality of fresh chicken breast meat. The proteinrich poultry meat could provide a faster microbial growth environment than those with lower protein meat. The water content of raw broiler chicken meat is around 74%. Protein and fat content are approximate ly 23% and 2%, respectively

PAGE 26

26 (Qiao, et al., 2002). Wattanachant et al. (2004) analyzed the biceps femoris and pectoralis muscles of Thailand broiler chicken meat and calculated protein content to be around 20%, fat content to be lower than 1%, moisture co ntent to be around 75%, and pH to be 5.9 to 6.6 for muscle samples. The water activity for poultry meat is about 0.98 to 0.99 which is based on storage environment and storage time (ICMSF, 1998). Slaughter processing and other operations also could impinge on intrinsic factors, such as the pH of chicken breast meat would fall in the range of 5.7 to 5.9, and the PSE (pale, soft, exudative) chicken meat color, caused by the poor practice and high stress of bird, is darker than normal meat. The pH of the PSE is lower than that of normal chicken breasts, because of rapid lactic acid accumulation in a short time (Stringer and Colin, 2000). In additional, food ingredients added to meat could change the pH and water activity, such as acid flavoring seasonings. Pat hogenic microorganisms require a slightly acidic pH level of 4.67.5. The pH value of chicken breast meat has an optimum acid tolerance level for the spoilage organisms and pathogen organisms to grow (ICMSF, 1998; White, 2000; Serv S afe E ssential 5th, 2006) For example, the minimum pH for Salmonella and Pseudomonas growth are 4.0 and 5.5, respectively. So if ingredients alter muscle pH to the optimum acidity condition, the type and rate of microbial proliferation would change. Environmental redox potenti al is an important determinant of microbial growth. Aerobic microorganisms required positive redox potential value, while anaerobes required negative redox value. The redox potential of poultry was reported to range from 150 mV to +250 mV and has similar level with beef, pork and lamb (ICMSF, 1998). Biological structure of poultry meat is also susceptible to microbial growth. Many microbes reside under the skin of poultry providing more

PAGE 27

27 occasions to assault the muscle. Thus, skin and muscle tissue of poult ry provide good substrates for bacteria growth (ICMSF, 1998). Extrinsic Factors In additional to intrinsic parameters that could affect the rate and extent of microbial growth, extrinsic factors influence growth of microorganisms as well. Therefore, the c ombination of factors could be determinants of the shelf life of meat. The extrinsic factors include storage environment such as storage temperature and time, relative humidity of the environment, and the presence and concentration of gas around chicken meat in package, and antimicrobials added (Stringer and Colin, 2000). Storage time could affect the population of microorganisms and the temperature could affect the multiplication and rate of microorganisms. For example, psychrotrophic bacteria have higher adaption under chill conditions. So, improper storage temperature is the most important factor affecting perishability of meat, especially in muscle meat. The rate of spoilage of fresh poultry at 10C is about twice that at storage of 5C, and that 15C s torage is about three times faster than the when the storage temperature is 5C (Jay, 1992). Pearson and Dutson (1994) reported the same conclusion that the mean shelf life at 0C is 14 days, and when the storage time increases to 5C, storage days are reduced to 7 days, and so on. During the high humidity of refrigerator storage, the meat spoilage microorganism is mainly psychrotrophic bacteria. These organisms grow well under the chilled condition and cause meat spoilage. Studies also revealed that vacuum and gas atmosphere storage could delay the spoilage of poultry. When compared with raw poultry stored in oxygen permeable film, vacuum package, and carbon dioxide flushed highbarrier film, the shelf life was 9 days, 10 days and 17 days, respectively (Jay 1992).

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28 Spoilage and Pathogenic Microorganisms Associated with Fresh Broiler Chicken Meat The bacteria harbored on poultry could be divided into pathogens (causing foodborne disease after food consumption) and nonpathogens (not associated with disease) Most nonpathogenic organisms, also called spoilage organisms, are still a concern of producers since spoilage organism could produce off flavor, discoloration and cause undesirable texture in the meat (Cunningham and Cox, 1987; White, 2000). Pathogenic microorganisms associated with fresh poultry are Salmonella, Campylobacter, Clostridium perfringens, Staphylococcus aureus, Listeria monocytogenes and Clostridium botulinum (ICMSF, 1998; White, 2000; Mead, 2004). Controlling growth of Salmonella Enteritis and Campylobacter jejuni continue to be the major concerns for the poultry industry in the USA. The United States Department of Agriculture (USDA) made a regulation that the maximum level of Salmonella allowed in poultry carcasses is 10% (Bauermeister et al., 2008). More efforts should be performed to reduce cross contamination during processing. Spoilage Organisms Associated with Raw Chicken Breast Meat The initial bacteria of raw poultry meat are mesophile microorganisms (Saucier et al., 2000). Immediately after processing, the isolated bacteria from fresh chicken carcasses were Micrococcus (50%), grampositive rods (14%), Flavobacteria (14%), Enterobacteriaceae (8%), Pseudomonas (2%), Acinetobacter (7%), and unknown genera (5%). Of these, only Pseudomonas and Acinetobacter grow faster at refrigeration storage for 10 days, and 90% of the bacterial species were Pseudomonas fluorescens in the later storage time (Russell, 2000; Charles et al. 2006; Mead, 2007). Under refrigeration storage conditions, organis ms generated fastest during refrigeration

PAGE 29

29 conditions, are termed psychrotrophic. The psychrotrophic microorganisms grow well at below 7C and produce visible colonies at 7C for 10 days, and the optimum temperature growth is between 20C and 30C (Jay, 1992). The primary species of psychrotrophic microorganism s is P seudomonas in fresh refrigerated poultry meat and mainly Pseudomonas fluorescens Pseudomonas putida and pseudomonas fragi (White, 2000; Blackburn, 2006). Pseudomonas organisms cannot grow under vacuum and adequate carbon dioxide conditions. They can proliferate under aerobic and less than 20% carbon dioxide storage. Other characteristics of P seudomonas are formation of off flavor and surface stickiness. At the beginning of spoilage, the microor ganisms exhaust glucose till completely depleted, and then degrade the small compounds, like amino acids. Prior to slime formation, the metabolism of amino acids release off flavor substance s. Later, colonies appear on the surface of meat. Finally, colonie s grow together and develop a coat on the meat. The off flavor could be detected when counts are up to 7 8 log 10CFU/g and the slime and sticky coat could be detected when the counts are over 8 log 10CFU/g Russell (1998) explained that the dominant bac teria that produced off odor were Shewanella putrefaciens, Pseudomonas fluorescens and Pseudomonas putida. Previous studies also demonstrated that majority of bacterial species on poultry meat in the later stage of storage were Pseudomonas fluorescens Ru ssell (1997) reported that the sulfur compound from off flavor in poultry meat was mainly produced by Pseudomonas and Shewanella spoilage bacterial. Methods that measure spoilage in poultry include chemical methods (such as discoloration, release of gas, or chemical contents), physical methods (such as pH

PAGE 30

30 value change, surface tension), bacteriological and physiochemical methods. For example, Jay (1992) pointed out that the total psychrotrophic counts and water holding capacity could be indicators of meat spoilage. Pathogenic Organisms Associated with Raw Poultry Breast Meat. Poultry products are a common media for foodborne illness outbreaks (ICMSF, 1998), because inappropriately cooling and heating, time and temperature abuse, undercooking, improper handling of raw poultry meat and cross contamination are fundamental factors that lead to outbreak of foodborne illness. Pathogenic bacteria associated with poultry meat are Salmonella e nteritidis Campylobacter jejuni, Clostridium perfringens, Staphylococcus aureus, Listeria monocytogenes (ICMSF, 1998; White, 2000; Mead, 2004). Salmonella Enteritidis may be found in the intestinal tracts of warmblooded animals such as poultry meat and egg products. Campylobacter jejuni is one of the most common sources that cause diarrheal illness in humans. Monitoring cross contamination and not consuming undercooked poultry meat could reduce infection of this disease. Food poisoning due to Clostridium perfringens is mainly associated with improper storage of cooked turkey. Staphylococcus aureus has been isolated on human hands and ready to eat food such as chicken salad. Live poultry can carry Staphylococci in bruised tissue, infected lesions, inside of nasal, arthritic joint, and on breast meat surface (ICMSF, 1998). Mos t of the original staphylococci organisms on birds are damaged after scalding, however, the birds are infected by Staphylococcus aureus from defeathering machine. Staphylococcus aureus isolated from poultry are never been reported causing the serious foodborne outbreak, and under low temperature storage conditions, Staphylococcus aureus is a poor competitor with other spoilage organisms on raw meat and poultry. The majority of Staphylococcus

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3 1 aureus foodborne illness associated with poultry is due to the im proper handling of the cooked poultry product. Therefore, Staphylococcus aureus is not a concern for public health (ICMSF, 1998). Listeria monocytogenes is often present on raw meat, and can be destroyed by cooking, but poor hygiene practices still can cau se consumer foodborne illness. However, there is no evidence shown that Listeria monocytogenes multiplication on raw meat is the primary causative of listeriosis foodborne illness outbreak. Therefore, Listeria monocytogenes is generally associated with cooked and ready to eat poultry products. B y far, Salmonellae and Campylobacter are the most important pathogens associated with raw poultry product (ICMSF, 1998). Salmonella Salmonella is a gram negative, facultative anaerobic, nonspore forming, and rodsh aped bacteria. The majority of Salmonella species can move by peritrichous flagella. USDA (2009) reported that Salmonella is a member of the family Enterobacteriaceae, many of them can cause human illness and they are catalase positive, oxidase negative, and hemoorganotrophic. Salmonella has the ability to metabolize nutrients by both respiratory and fermentative routes. It comprises two species: Salmonella bongori and Salmonella enterica. Salmonella enterica causes intestinal disease, and could be isolat ed from human and warm blooded animals. Salmonella enterica account for more than 99.5% of serotypes. S. typhi, S. typhimurium and S. enteritidis are three main serovars of S. enterica. S. enteritidis is the most common sources of foodborne illness in the United States. Vertical and horizontal transmissions of Salmonella are the primary pathways of cross contamination in poultry plants. Scientists have identified more than 2,400 serotypes of the genes Salmonella bacteria. Of these, two serotypes are specifi c poultry pathogens ( S. gallinarum and S. pullorum) (Breytenbach, 2004; Revolledo et al.,

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32 2009). Paratyphoid Salmonella ( S. e nteritidis, S. t yphimurium, and S. typhi ) have a wide host range and could not lead to poultry disease, but these serotype pathogens are of major concern for public health. Salmonella outbreaks cost an estimated $ 3 billion annually in the United States. Salmonella is named after Dr. D. E. Salmon in 1900. He, along with his coworkers was the first person to observe and report the characteristics of Salmonella Choleraesuis Since 1933, the term Salmonella has prevailed (Cunningham and Cox, 1987). Salmonella growth range is 7C to 47C, the optimum growth temperature range being 35C to 37C, which is close to body temperature. If the t emperature is below 6.7C, the growth of Salmonella could be prevented. Temperature over 70C could kill Salmonella and refrigeration temperature prevents the growth of Salmonella but will not kill them (ICMSF, 1998; White, 2000). Salmonella can grow betw een pH values from 4.0 to 9.0 and the optimum pH range is 6.5 to 7.5 (White, 2000). Jay (1992) reported that the best pH for S almonella growth is between 6.6 and 8.2. The minimal water activity for growth of Salmonella was about 0.94 (White, 2000). Live poultry are the primary reservoir of Salmonella bacteria. Some organisms on the carcasses surface may spread to other carcasses during processing, packing, distribution and holding and further processing. There are mainly three routes of Salmonella crossco ntamination: first, feed and drinking water; second, birds get infected by vertical transmission, namely, from contaminated eggs to their offsprings; and the third vehicle is called horizontal transmission, which means that healthy poultry is contaminated by other carcasses, or equipment, tools, workers and other animals (Mead, 2004). Researchers concluded that Salmonella horizontal transmission could be

PAGE 33

33 the major determinant of the final microbial load and types on meat products. However, the initial sour ce associated with poultry is feeding contaminated water and food (Cunnin gham and Cox, 1987; Mead, 2004). One unique characteristic of some Salmonella strains is the ability to penetrate from chicken skin to inside organs of chicken (Mead, 2004). An infect ious dose of Salmonella on poultry carcass is small, probably from 15 to 20 cells, but sometimes more than 14 log 10CFU/g of skin occurred (ICMSF, 1998). However, a low dose level of Salmonella ingesting contaminated meat might be lethal. Control methods employed in industry are to avoid crosscontamination between flocks and to provide poultry vaccination on farm. The control recommendation methods for producers are to keep carcass Salmonella free, avoid feeding contaminated food and water, and prevent cr oss contamination between carcasses. For consumers and retailer s, improper cooling, holding, reheating, and undercook ing contribute to Salmonellosis outbreak s (Cunningham and Cox, 1987). Campylobacter The Campylobacter species has been considered the main common sources of human bacterial gastroenteritis in the United States (Isohanni and Lyhs, 2009). Egg and poultry products are the primary sources of C. jejuni (ICMSF, 1998; Mead, 2004). The most import ant risk of Campylobacteriosis is to consu m e undercoo ked poultry meat or to mish andle raw poultry meat (Isohanni and Lyhs, 2009; Nather et al., 2009). Once birds get infected, Campylobacter spp. spread fast (Nather et al., 2009). Horizontal transmission is the major rout e to spread organism s. Vertical transm ission of campylobacter rarely occurs since only a few bacteria could survive on eggs. In contra s t to Salmonella, Campylobacter cannot survive under long dry conditions of feeding food,

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34 so the food is not the source for transmission of Campylobacter (Mead, 2004). Bacteria counts on carcasses are likely to increase during defeathering and evisceration (Nather et al., 2009). Campylobacter are gram negative, very slender curved to spiral shaped rods, 0.20.4 m in width and length is 1.53.5 m Most Campylobacter are motile by a single flagellum. Campylobacter c an survive well at microaerophilic conditions. The atmosphere that contains 5% oxygen and 10% carbon dioxide is optimum growth for Campylobacter (Cunningham and Cox 1987; Simmons et al., 2008). Keener et al. (2004) stated that Campylobacter jejuni is unusually sensitive to oxygen and dehydration. Jay (1992) also stressed that Campylobacter requires low oxygen approximately 6 % to 8% to grow, and if oxygen is more than 21%, the growth of Campylobacter je juni is inhibited. Campylobacter has a higher optimum growth temperature than Salmonellae (Mead, 2004). Studies reported that when the internal temperature of ground beef reached 70C, Campylobacter counts were reduced 7 log cfu / g, when tested after 10 minutes. When placing chicken carcass into 18 C storage condition, Campylobacter counts were reduced by 5 log cfu /g (Jay, 1992). Antimicrobials Used in Chicken Breast Meat to Control Pathogenic and Spoilage Bacteria ICMSF (1998) listed three mechanisms that could contribute to attachment of bacterial regarding poultry carcasses surface, there are retention, entrapment and adhesion mechanisms. Retention occurs when poultry carcasses contact the contaminated water. The bacteria coming from the contaminated w ater is residual and develops film on the surface of carcasses. Therefore, the microbial load on the surface of carcasses has positive effect with bacteria in the water. Entrapment occurs when

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35 the muscle tissues are swollen by absorbed water, followed by bacterial penetration into the deep channel or crevices from the outer poultry carcass surface. This processing occurs easily in broken skin, meat and cut meat, such as chicken breast meat. Also as time increased, bacteria retained on the surface of carcass, might change to entrapped situation. Under the circumstances, spraying carcass with wat er cannot remove contaminants. Antimicrobials are added into spraying water and remove these entrapped bacteria. Adhesion occurs in the soft tissue and loosed connective tissue but not all bac teria are capable of adhesion to these tissues. Adhesion bacteria function when the optimal conditions such as neutral pH, low ionic strength, and immersion in water for some time occur When adhesion occurs, spraying, rinsing, and immersion are not good methods to reduce microbial load. Researchers reported that adding salts into immersion water could decrease the degree of adhesion and increase ionic strength. The effect iveness of chemical compounds depends on bacteria retained, entrapped or adhered to the tissue. Fresh broiler chicken meat is prone to microbiological spoilage due to providing excellent substrate for microbial growth If fresh meat is stored under inappropriate conditions or is not treated with preservatives, it becomes very perishable (Mead, 2004). The purpose of chemical intervention strategies in chicken carcasses is to prevent contaminants, remove contaminants, and extend lag phase of pathogenic and spoilage organisms, or destroy contaminants completely ( George, 1989). Many Intervention decontaminants are described and grouped into physical, chemical and combination chemical and physical methods. Physical methods include rinsing, spraying, steaming with hot or cold water, U ltra high pressure, irradiation, P ulsed E lectric F ield, U ltrasonic

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36 energy, and UV light. Chemical approaches include but not limited to chlorine (chlorine dioxide, cetylpyridinium chloride, sodium hypochlorite, stannous chloride, timsen, acidified sodium chlorite, sodium chlorite), organi c acids (lactic acid, acetic acid, citric acid, propionic acid) and organic acid salt preservatives (sodium lactate, sodium sorbate, sodium citrate, potassium lactate; inorganic phosphates (trisodium phosphate, sodium t ripolyphosphate, acid sodium pyr ophos phate); bacteriocins (nisin, magainin; EDTAnisin); oxidizers (hydrogen peroxide, ozone, quaternary ammonium ) and other chemical compounds such as sodium metasilicate (Dicken and Whittemore, 1997; Kristen et al., 1997; Bolder, 1997; Bilgili et al., 1998; Russell, 1998; Russell, 2000; Aktas and Kaya, 2001; Jimenez Villarreal et al., 2003; Northcutt et al., 2005; Ricke et al., 2005; Economou et al., 2009; Quilo et al., 2009). In this literature review, the effectiveness of these chemical compounds in poultry processing plants and their mechanisms of action will be described in detail. The suitable chemical agents shoul d have effective ability with low concentration, fast working, without residual on the surface of the carcass, and no detrimental effect to co nsumers. The agents should not produce undesirable appearance, texture, color, odor and favor. Some of the chemical compounds listed above are suited for one process, but might fail in another. Some chemical compounds have been verified to control microbi al growth on lab level but can fail when applied under commercial plant conditions. For example, the problems could be meat color change, off flavor development, equipment and tools erosive In this literature review, the advantages or disadvantages of these interventions and their chemical actions and mode action will be explained.

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37 Chloride European Food Safety Authority ( EFSA, 2005) reported antimicrobials that c an be used in poultry carcasses include sodium tripoly phosphate, acidified sodium chlorite, chlorine dioxide, and peroxyacetic acid. In the United States, Chlorinated water was employed for carcass washing, spraying carcass or equipment and chiller water for online reprocessing to reduce microbial growth and cross contamination (EFSA, 2005; Nort hcutt et al, 2005). C hlorine solution prohibited the Salmonella growth in water, but failed to reduce the bacteria on the surface of carcasses (Brotsky and Bender 1991). T he most common antimicrobial product used in carcass spraying is acidified sodium ch lorite (Bauermeister et al., 2008). However, in chiller processing, chlorine dioxide is being used instead of acidified sodium chlorite because of stability of chlorine dioxide; however, the effectiveness of chlorine dioxide is influence d by the organic matters from wat er and chicken. Chlorine and organic matter could react and produce t rihalomethane, a mutagenic compound. The compound might cause cancer ( Cooper, 2009). Recently, researchers pointed out that chlorine solutions could react with organic matte r from high protein food such as chicken breast meat a nd produce semicarbazide (EFSA, 2005). In the light of the limited evaluation information, whether the compounds could threaten public health still needs further researches. Pearson and Dutson (1994) re ported that chlorine or acid spay ing could corrode equipment and tools when used to spray the poultr y carcass. Bauermeister et al. (2008) also reported that chlorine significantly lost its efficacy when the water contained high amount of organic matter and pH over 7.0. Acidified sodium chlorite (ASC) is FDA (U.S. Food and Drug Administration) and USDA approved for use as an antimicrobial intervention on post evisceration poultry

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38 products. ASC is the formation of sodium chloride with any acid that is generally recognized to be safe in food. The chemical formula of ASC is NaClO2. The pH range is 2.3 to 2.9 at concentration of 5001200 mg/L sodium chloride dip This solution can be applied either as a 15 second spraying or a 5 8 second. This treatment could result in 2 log reductions in Escherichia coli, Campylobacter spp., and Salmonella spp. For immersion chilled water, the concentration increases to 150 mg/L at a pH between 2.8 and 3.2 (EFSA, 2005). ASC provides an average 2.28 log reductions in E. coli and 2.56 log reductions in Campylobacter spp. The antimicrobial properties come from chlorous acid, which has stronger oxidation than either chlorine dioxide or chlorine. Chlorous acid oxidizes cellular constituents and disrupts protein synthesis (EFSA, 2005) Organic Acids and Their Salts Various organic acids could prohibit gram negative spoilage microbial growth attaching on surface of meat (Bolder, 1997). They could effectively reduce the microbial load in the scalding water but have no significantly eff ect on the carcasses (Dickens and Whittemore, 1997). Two common organic acids, acetic acid and lactic acid, have been investigated for possible utilization in the meat and poultry industry. This is because they are effective for reducing specific organisms and are generally recognized as safe (GRA S) (Pearson and Dutson, 1998). The organic acid treatment may impact meat color and flavor which are determined by the concentration and application of acid. Aktas and Kaya (2001) reported that concentration of l actic and citric acid over 1.0% could cause meat sourness. Bauermeister et al. (2008) reported that organic acids, including acetic, formic, citric, and lactic and propionic acid, could control microbial proliferation but could also bring about an undesirable flavor and color. He also pointed out that 0.022% peracetic acid and 0.012 % hydrogen peroxide in solution could

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39 maintain or increase the acceptability of flavor and color in poultry, in addition to its antimicrobial function. He drew the conclusion that low levels of propionic acid employed as antimicrobial in poultry chillers could reduce the population of Salmonella Typhimurium and Campylobacter jejuni on the final product without a change in organoleptic characteristics. Bilgili et al. (1998) repor ted that organic acid (acetic, citric, lactic, malic, mandelic and t artaric acid) stimulated chiller condition, decreased lightness and increased yellowness values, as levels of concentration increased. In addition, lactic acid with sodium benzoate could c ontrol proliferation of Salmonella on chicken skin when refrigerated. A combination of 1% lactic acid and 0.5% hydrogen peroxide has 4 log reductions of Salmonella. Bauermeister et al. (2008) indicated that when carcasses inoculated with Salmonella (106 cfu) or Campylobacter (106 cfu) peracetic acid at concentration as low as 0.0025% was effective in reducing Salmonella spp. and at concentration as low as 0.002% was effective in reducing Campylobacter spp., when placed into poultry chiller. They also reported that the combination of 1% acetic acid and 3% hydrogen peroxide could significantly decrease the load of Escherichia coli, Salmonella and Listeria innocua when sprayed on a previously inoculated beef carcass. Russell (1998) reported that 5% or more l actic acid eradicated all spoilage organisms isolated from broiler chicken. Bolder (1997) reported that poultry carcasses treated with 12% lactic acid solution after slaughter and during storage reduced bacteria population without a change in color or flavor. Brotsky and bender (1991) reported that using lactic or acetic acid above the specified level would control bacteria but was unacceptable with regards to sensory change. O rganic acid antimicrobial

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40 efficacy is determined by the level of acid and the pH value of the solution. L actic acid removed bacteria attached to lean pork faster than bacteria attached to fatty parts. A combination of lactic acid and sodium benzoate could extend the shelf l ife and maintain meat quality. Therefore, organic acids, espec ially lactic acid, have the potential to be promising meat and poultry surface decontaminants. The addition of organic acid and their salt compounds as preservatives in poultry and meat products has been utilized in commercial meat plants (Alvarado and Mc kee, 2007). These chemical antimicrobials include sodium lactate, potassium lactate, sodium citrate, and combinations of these compounds. Jimenez Villarreal et al. (2003) determined that cetylepyridinium chloride, chlorine dioxide, lactic acid and trisodi um phosphate could be effective in reducing the numbers of bacteria. Also cetylepyridinium chloride and trisodium phosphate could maintain the meat color and improve sensory characteristics and decrease the lipid oxidation rate compared to the untreated ground beef. Researchers also concluded that potassium lactate could be effective in reducing Listeria monocytogenes on various meats. Previous studies pointed out that sodium lactate, sodium acetate, sodium diacetate, p otassium lactate, sodium citrate, the combination of s odium lactate and sodium diacetate, and the combination of sodium lactate and potassium were able to prevent the microbial population and increase the sensory evaluation of meat product (Shafit, 2000; White, 2000; Alvarado and Mckee, 2007) Shafit (2000) reported that 1.25 % lactic acid could lead to the discoloration of meat, and c oncentration of more than 2.0 % could cause flavor problems. Sodium lactate also has these problems. Williams and Phillips (1998) determined that increasing the concentration of sodium lactate reduced the population of psychrotrophic counts on

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41 chicken breast meat. However, over 2% of sodium lactates could result in the cooked chicken meat having a bitter taste, so sensory problems limit the concentration level of chemicals use ( Williams and Phillips, 1998 ). The effect of salt of organic acid has been attributed to cross molecular membranes and acid crosses the membrane barrier to acidify the cell interior. Sodium Tripolyphosphate The most commonly used poultry mari nade is sodium tripolyphosphate, which had been shown to increase meat yield and water holding capacity, as well as improve color and texture. Phosphate salt could prevent bacterial growth on carcass skin and not influence color or texture. Sodium tripoly p hosphate as an intervention strategy could control the growth of Salmonella, Campylobacter and E. coli O157:H7 (Weber et al., 2004). The chemical mode of action of sodium tri poly phosphate differs from chlorine, ozone, chlorine dioxide and acidified sodium chlorite, which could react and quickly remove unsaturated bonds from solution, and reduce the antimicrobial effect. S odium tripo lyphosphate is an alkaline salt. The high pH value of sodium tripolyphosphate (pH 12.1) could destroy cell membrane and damage the fat film of meat. The hydroxyl radical, remaining on meat surface, continues to function as an antimicrobial and retard the growth of bacterial after treatment (Rick e et al., 2005). It can be applied to remove retention and entrapment microorganis ms. Brotsky and B ender (1991) r eported that the death rate of Salmonella increased during scalding if the pH value of scald warm water was adjusted to around pH 9.0. The pH adjusting agents were sodium hydroxide, potassium hydroxide, sodium carbonate, and alkaline tripolyphosphate. He also concluded that trisodium phosphate dodecahydrate had the most powerful lytic action to

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42 Salmonella typhosa, compared with monosodium disodium, and dipotassium orthophosphate. In addition, treating poultry carcasses or part s with 4% to 12% trisodium or tripotassium phosphate dodecahydrate was equally effective as sodium hydroxide, or phosphoric acid and sodium hydroxide. Alvarado and McKee (2007) mentioned that acid pH phosphates will lower water holding capacity, while alka line phosphat es had the reverse trend, which means that meat samples had a higher cooking yield, higher water holding capacity, more juice r and tender, longer shelf life, higher color stable capacity, lower purge lost, and lower oxidation acidity after treated with alkaline phosphate. Sodium Metasilicate Sodium metasilicate (SMS) share some common with sodium tripolyphosphate. It is an alkaline salt with a high pH the ability to buffer. The pH value of a 1% aqueous solution is about 12.3, and the pH value of 5% aqueous solution is approximate 12.7. Sodium metasilicate has strong corrosive and penetrating ability. When sodium metasilicate reacted with protein and collagen, the saponifying effect occurs on lipid and d ehydrates the tissue and cells. It can ma intain pH stability when reac ted with muscle tissue ( Temple and Smith, 1997). Sodium metasilicate as antimicrobial has been of interest in for years. Sodium metasilicate is considered GRAS (Generally Recognized as Safe) under 21CFR173.310 and is permitted to be added directly to food for human consumption ( FDA, Code Federal Register, 2006). The U SDA approved the application of sodium metasilicate on raw beef carcasses as an a nti microbial processing aid (USDA, 2009). Up to 4% (plus or minus 2% ) of a solution could be used in the raw beef carcasses.

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43 Quilo et al. (2009) applied the 4% SMS (w/v) to beef trimming and observed that the SMS t reated sample was much juicier, had lower shear force, had less cook ing loss than the control, and had no difference in sen sory characteristics compared to the control product Ben der (2006) reported that the protein containing products contacted with alkali silicate solution for a period of time could sufficient to saturate the food products and absorbed the solution into product. He also concluded that SMS had lower cooked loss than untreated samples. Additionally, sodium metasilicate at concentration of 0.35% had slightly higher cooking yield than 0.35% phosphate treated samples. W eber et al. (2004) indicated that exposure o f E. coli O157: H7 to 0. 4 % SMS solution for 20 minutes had same effectives with exposure to 0.6% SMS solution for 510 seconds which caused 100% inhibition without recoverable. Recently, USDA approved sodium metasilicate for injection i nto raw meat and poultry as a 2% marinade solution by weight (UDSA, 2009). However, there is no documentation of the affect of sodium metasilicate in poultry products and little documentation recording the mechanisms of using sodium metasilicate to inhibit the growth of micro organisms. Therefore, SMS may have the same effectiveness in control growth of Salmonella and Campylobacter and may have the same mechanical action as sodium tripolyphosphate. Moreover, it may also improve the physical and chemical properties without senso ry undesirable detectable. Also it may have no side effect to environment residue which may be different with sodium tripolyphosphate. Also it may also be more effective at extending shelf life when combined with other technologies.

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44 CHAPTER 3 MATERIALS AND METHODS This study was conducted in three phases. Phase I included preliminary studies to determine application method and to evaluate the effectiveness of sodium metasilicate (SMS) at the USDA approved level for poultry meat. Phase II included preliminary studies to determine the effectiveness of sodium metasilicate at approved and elevated levels and a shelf life study. Phase III included to investigate the effectiveness of sodium metasilicate at the USDA approved level and elevated levels on antimicrobial, sensory, chemical and physical characteristics of fresh chicken breast meat and a shelf life study. Marination processing was conducted at the University of Florida Meat Processing facility, and all analyses were performed in the Meat Research Laboratories. Phase I. Preliminary Study: Application Method and Evaluation of Sodium Metasilicate at Approved Level for Poultry Meat Sample Preparation USDA GRADE A 97% fat free boneless skinless chicken breast fillets with rib meat and with expiration date of at least 7 days were purchased from a local supermarket. In order to insure the freshest fillets were used in the study, the fillets were purchased on the day of arrival to the store and immediately transported to the Meat Research Laboratory, and stored at 4C in a walk in cooler. Sample Treatment and Marination Yield Experiment o ne Experiment one was conducted in a 4C walk in cooler. The fillets were randomly and evenly divided into three groups. A s tillmarinating process was used wherein the fillet s were weighed and immersed into solutions containing either 0, 1 or 2% sodium metasilicate (AVGARDXR, Lot. U012106, Danisco USA Inc., New century, KS) for 30

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45 minutes (15 minutes for each side). The treated fillets were drained for 2 minutes, weighed and two fillets were packaged in a Cryovac 2.0 tray (Type CS978, Mulinix package Inc., Fort Wayne, IN), overwrapped with 18X2000plastic foodservice film (CompanionsTM, Unipro Foodservice Inc., Atlanta, GA) and stored at 4C for analysis. All samples were analyzed for marination yield, pH, total psychrotrophic counts, cooking yield, color, shear force and sensory evaluation on day 0. Experiment t wo Experiment two was conducted in the Meat Processing facility under simulated plant condit ions in a 2C proces sing room. Eighteen fillets were randomly and evenly divided into three groups. The fillets were weighed and placed into a vacuum tumbler (Lyco vacuum tumbler, model 40, Columbus, WI) with marinade solutions containing either 0, 1 or 2% sodium metasilicate solutions and tumbled under vacuum for 20 minutes at approximate 172.32 kPa ( kilopascal) of pressure. The objective was to use the marinade solution to yield 10% increase in the total fillet original batch weight for each treatment. A v acuum tumbling proc essing was performed in a 2C cold room to prevent fillets from increasing in temperature during marination. Control treatment samples were marinated with tap water (2C). For 1% and 2% treatments, the sodium metasilicate compound was completely dissolved in tap water before marinated with samples. Except for tap water and sodium metasilicate, no other ingredients were added to the fillets in this study. The treated fillets were weighed and packaged in trays as previously discussed. Two fillets were placed into each tray and stored at 4C for 6 days. For each treatment, two packages were randomly collected on 0, 1, 3 and 6 days and analyzed for marination yield, pH, total psychrotrophic counts, cooking yield color,

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46 Instron and sensory evaluation. The marinat ion yield (%) was calculated using the following equation: Marination Yield (%) =100* W1/W2 (3 1) W2 represents weight of fillets premarination, g W1 represents weight of fillets post marination, g pH Analysis The pH analysis was the same for e xperime nts one and two. The pH value was determined immediately after completing microbiology analysis. The pH value was measured using a pH Meter (Accumet Basic AB15, Fisher Scientific, Fair Lawn, NJ). Prior to analysis of pH for each treatment, the pH meter was calibrated using pH buffers 4.00 (SB101500, Fisher Scientific, Fair Lawn, NJ) and 7.00 (SB 107500, Fisher Scientific, Fair Lawn, NJ). The probe was placed into the sample homogenate and allowed to equilibrate for one minute before the pH reading was rec orded. All pH readings were performed in duplicates. Cooking Yield Analyse s Experiment one: Grill reconstitution m ethod The grills (Hamilton beach, proctor silex, Inc., Southern Pines, NC) were heated to 176.7 C approximately 15 minutes. The fillets from the same treatment were placed on the same grill, and were heated for approximately 30 to 40 minutes. The fillets were turn over when the grill line occurred on the surface during grilling. The copper constantan thermocouples were inserted the thickest part of fillets before grilling. The fillets were stopped cooking when the internal temperature reached 74 C monitored with thermocouples attached to a potentiometer. The weights (Mettler Toledo scales, Mettler

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47 instrumental corp., Model: MS 3001S 103, Hightstown. NJ) of before and after cooked fillets were recorded and cooking yield (%) was calculated using the following equation: Cooking yield % = 100* W2/W1 (3 2) W1 represents the weight before grilling, g W2 represents the weight after grilling, g Ex periment t wo: O ven r econstitution m ethod Four fillets of each treatment were placed in a roasting pan. The roasting pan was covered with aluminum foil (Handi Foil; 18x 500, Wheeling, IL,) to avoid moisture lost from fillets. The fillets were baked in a c onventional gas oven (Model: JGRS14 GE Built In Gas Oven) at 176.7 C, until internal temperature reached 74 C which was monitored with copper constantan thermocouples attached to a potentiometer. The copper constantan thermocouples were inserted into the thickest part of the fillets before baking. The oven was preheated approximately 20 minutes until the oven temperature reached 176.7 C. The weights (Mettler Toledo scales, Mettler instrumental corp., Model: MS 3001S 103, Hightstown. NJ) of the fillets were recorded before and after cooking, and cooking yield (%) was calculated using the following equation: Cooking yield % = 100* W2/W1 (3 3) W1 represents the weight before cooking, g W2 represents the weight after cooking, g Microbiological Analyse s E xperiment o ne The treated fillets were analyzed for total psychrotrophic counts on each assigned sampling days. Twenty five gram fillets were aseptically cut and placed into a sterile stomacher bag (400ml, Fisher Scientific, Pittsburgh, PA ). The 225 ml sterile 0.1%

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48 peptone water (Cat. No. DFO1897174, Detroit, MI) was poured into the stomacher bag. The stomacher bag was manually massaged for two minutes to loose surface bacteria. One milliliter of homogenate aliquot from stomacher bag was transferred into a test tube, which containing 9 ml sterile 0.1% peptone water. Two tubes were employed for each treatment from 101 to 102 serial dilution. The contents of tubes were mixed using vortex (Votex Geniz 2TM Cat. No. 12812 Model G 250, Fisher scientific, McGaw, IL) for 15 seconds to insure the bacterial evenly distributed. 3M Petrifilm Aerobic count plate (Cat. No. 6406, Fisher Scientific, Pittsburgh, PA) was placed on a level surface. The top film was lifted, and 1 milliliter aliquot from each tube was asceti cally transferred into the plate, and a plastics squared spread was placed on the top center of plate and dispersed the aliquot on plate. The 3M Petrifilm Aerobic Plate Count was held at room temperature for 15 minutes. Plates were incubated at 7C refriger ator for 48 hours in a horizontal position for the total psychrotrophic count (Hamm 2001). Microbiological counts were expressed as Logarithmic Colony Forming Units per grams (log cfu/g). The counts were recorded when containing 25250 colonies on plate. All samples were plated in duplicates. Experiment t wo The sample homogenate and serial dilutions were prepared as discussed in Experiment One. Approximately 0.1 mL aliquot of the diluted sample homogenate from each serial dilution was aseptically transferred into sterile disposable 100 x 20mm Petri plates (Cat. No. 08757103C, Fisher Scientific Suwanee, GA) that contained prepoured hardened Tryptic Soy Agar (No.1010617, MP Biomedicals, Inc., Solon, OH). The homogenate was spreaded on the plates using a sterile glass hockey stick. The stick was sterilized with 70% ethanol and flamed before spreading. The plates were

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49 incubated aerobically at 7C for 10 days to determine the total psychrotrophic counts (Hamm, 2001). Microbiological counts were expressed as Logarithmic Colony Forming Units per grams (log cfu/g). The counts were recorded when 25250 colonies were on the plate. All plates were done in duplicates. Objective Color Measurement The color of raw and cooked fillets was measured with the Hunter MiniScan XE plus colorimeter (Hunter Associates Laboratory, Inc, Reston, VA) in the same manner for experiments one and two. The colorimeter was calibrated with a standard black tile and white tile as recommended by manufacturer. Fillets (two fillets per pack age) were measured at a total of four different locations for L*, a* and b* values. The instrumental color of L* a* b color spectrum were recorded, where L* represents the total light reflected on a scale ranging from 0 = black to 100 = white, a* represe nts the amount of red (positive values) and green (negative values), and b value represents the amount of yellow (positive values) and blue (negative values). Warner Bratzler Shear Force Analysis The 1.0 cm cooked strips were employed for shear force measurement The cooked 1.0 cm strips w ere covered with aluminum foil and stored at 4C for 18 hours prior to shear force measurements. Texture measurements were conducted as described by Lyon and Lyon (1991). Each strip was oriented in the Warner Bratzler shear attachment, which was attached to the Model 1011 Instron Texture machine (Model 1011 Instron, Instron Corporation, Norwood, MH). The speed of cross head was 200 mm/min with a 50 kg load cell. The full scale range was 10 kg (Williams and Phillips 1998). The Warner Bratzler shear force values were recorded in kilograms. Five values were obtained from each treatment. All treatments were done in duplicates.

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50 Sensory Evaluation Analyse s Experiment one: Grilled f illets The fillets were cut into two 1.9 cm wide strips paralleled with the direction of the fibers. One strip was separated into three or four cubic cm for sensory evaluation, and another strip was used to determine instrumental texture. The cubes were trimmed into uniform size. Two cubes of each treatment were placed into a prewarmed container to keep the serving temperature at approximate 55C. The serving containers were labeled with one digit numbers. The sensory evaluation was performed in the Meat Laboratory sensory room equipped with ele ven separated booths. Each booth was equipped with a ceiling lighting system with red, white, blue, or yellow lighting as needed (Williams and Phillips, 1998). The eight point hedonic scoring scales were employed for Juiciness, chicken flavor intensity, ov erall tenderness and a six point hedonic scoring scale was employed for off flavor. The samples were evaluated in an informal taste test by two experienced panelists. Experiment t wo: B aked fillets The panelists were recruited from faculty, undergraduat e and graduate students and staff in the Department of Animal Sciences who had participated in previous poultry sensory evaluations. The panelists were trained to comprehend the conception of Juiciness, tenderness, and chicken flavor intensity and to describe off flavor. Juiciness evaluation included two treatments. Samples were baked in a conventional gas oven and covered with aluminum film to retain maximum moisture, and another group of samples were grilled to produce samples with lower moisture content than the baked samples. Tenderness evaluation included two treatments of chicken tenderloin. One group of samples were baked in a conventional gas oven and covered with aluminum

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51 film to retain maximum moisture, and another group of samples were grilled, allo wed to cool at 4C for 15 minutes, and reheated in the microwave (Microwave Oven, Model: NNS961, Panasonic, San Francisco, CA) for 3 minutes to produce a tough texture. Chicken flavor intensity evaluation included using different marinade solution and tim e. One treatment was soaked into chicken broth overnight, the weight of chicken broth marinade accounted for 30% total weight of fillets, this treatment had stronger chicken flavor. Another treatment was marinated with tap water and employed still marinat ed for 30 minutes, the amount of tap water was 10% of fillets weight, and baked the samples at 176.7 C. The marination processing was performed at 4C cooler. Off flavor evaluation included four treatments. Panelists were trained to indentify the off flav or descriptors, such as salty, metallic, and bitter. The samples were marinated with tap water, 2% sodium chloride (salty), 2% of potassium chloride (bitter) and 0.5% sodium tripolyphosph ate (metallic), and then baked in a conventional oven at 176.7C, unt il internal temperature reach 74C. The panelists were also trained to fill in the sensory sheet. The eight point hedonic scoring scales were employed for juiciness, chicken flavor intensity, and tenderness evaluation, where 8 represents extremely juicy, extremely intense and extremely tender, 7 represents very juicy, very intense, and very tender, 6 represents moderately juicy, moderately intense, and moderately tender, 5 represents slightly juicy, slight intense and slight tender, 4 represents slightly dry, slight bland and slight tough, 3 represents moderately dry, moderately bland and moderately tough, 2 represents very dry, very bland and very tough, and 1 represents extremely dry, extremely bland and extremely tough. A six point scale was utilized f or off flavor

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52 evaluation. 6 represents none detected, 5 represents threshold; barely detected, 4 represents slight off flavor, 3 represents moderate off flavor, 2 represents strong off flavor and 1 represents extreme off flavor. Cooked meat was sectioned for sensory and instrumental texture measurements as described by Lyon et al. (2005) with some minor changes. The fillets were cut into 2 to 3 cubic cm wide strips paralleled with the direction of fiber. On strip was employed for instrumental texture, and another strips were employed for sensory evaluation. The cubes were discarded when the fibers from strips were not paralleled. The cubes were trimmed into uniform sizes. Two cubes of each treatment were placed into a prewarmed container to keep the serv ing temperature at approximate 55C. The serving container was labeled with one digit number. All treatments for sensory evaluation were served at the same time. Phase II. Preliminary Study: Determination of the Effectiveness of Sodium Metasilicate at Approved and Elevated Levels and a Shelf Life Study. In p hase II, the sampling days included 0, 1, 3, 5, 7, 9 days. The fillets were marinated with tap water that contains 1, 2, 3 or 4% sodium metasilicate. The material s and methods for sampling preparation, sampling treatment, marination yield, pH analysis, microbiology analysis, color, cooking yield and sensory evaluation were the same as phase I in experiment two. This preliminary study not only determined the effectiveness of the USDA approved levels, but also evaluated the effectiveness of elevated levels of sodium meta silicate on the shelf life of poultry meat. In addition to the parameters determined i n experiment II in phase I, water holding capacity values were determined.

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53 Water Holding Capacity Anal yses Water holding capacity with sodium chloride. The water holding capacity method described by zhuang et al. (2008) was conducted in this study. The treated fillets were minced with food processor (Braun Multiquick Hand Blender, Model: MR 400 HC, Type 4185, Lighthouse Point, FL). Ten gram minced samples were placed into a 50 ml tube containing 15 ml of 0.6 M sodium chlorine solution and vortexed (Votex Geniz 2TM Cat. No. 12812 Model G 250, Fisher scientific, McGaw, IL) for 1 minute per tube to ensure evenly distribution. The tubes were placed in a 4C cooler for 15 minutes prior to centrifuge. The centrifuge machine (Superspeed Refrigerated Centrifuge, Sorvall RC 5B, Beverly, MA) was turned on approximate one hour before measuring. The tubes were centri fuged at 3000 rpm at 4C for 15 minutes. The liquid was decanted, and the solid material was maintained in the tube. The weights of before and after centrifuged meat were recorded. Water holding capacity with distilled water The water holding capacity p ercentage values also were determined by distilled water method. The purpose of measuring these values with distilled water were to compare with fillets measured with sodium chloride. Except for addition of distilled water, t he procedure to determine water holding capacity was the same as using sodium chloride. Therefore, the 15 ml distilled water in place of sodium chloride was added into tubes that contained ten grams minced samples. The samples were analyzed in duplicate. The data for this method were co llected through day 3 to day 9. The same equation was used for these two methods. WHC (%) was determined by using the following equation: WHC % = 100 (W1 W2)/W3 (3 4)

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54 Where W1 represents solution added into the sample, g W2 represents solution removed, g W3 represents the meat sample mass, g Phase III. Investigation of the Effectiveness of Sodium Metasilicate at the USDA Approved Level and Elevated Level on Antimicrobial, Sensory, Chemical and Physical Characteristics of Fresh Chicken Breast Meat Stor ed at 4C for 9 Days In phase II test, the sampling days included day 0, 1, 3, 5, 7 and 9, and i n phase III the sampling days included day s 0, 1, 3, 5, 6, 7, and 9, and purge loss was measured. The procedures of sampling preparation, sampling treatment, m arination process, pH measurement, microbiology analysis, and water holding capacity w ere the same as phase II tests. The parameters of sensory evaluation, raw meat color, cooked meat color, cooking yield, Warner Bratzler shear force were perform ed in dupl icates in phase III. The treatments included 0 (control), 1, 2, 3, and 4% sodium metasilicate in marinade solution. Sample Preparation USDA GRADE A 97% fat free boneless skinless chicken breast fillets with rib meat and with expiration date of at least 7 days were purchased from a l ocal supermarket. In order to insure the freshest fillets were used in the study, the fillets were purchased on the day of arrival to the store and immediately transported to the Meat Research Laboratory, and stored at 4C in a walk in cooler. Sample Treatment and Marination Yield Experiment was conducted in the Meat Processing facility under simulated plant condit ions in a 2C processing room. One hundred forty fillets were randomly and evenly divided into five groups. The fi llets were weighed and placed into a vacuum tumbler (Lyco vacuum tumbler, model 40, Columbus, WI) with marinade solutions

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55 containing either 0, 1, 2, 3 or 4% sodium metasilicate solutions and tumbled under vacuum for 20 minutes at approximate 172.32 kPa of pressure. The objective was to use the marinade solution to yield 10% increase in the total fillet original batch weight for each treatment. Vacuum tumbling processing was performed in a 2C cold room to prevent fillets from increasing in temperature duri ng marination. Control treatment samples were marinated with tap water (2C). For sodium metasilicate treatments, the sodium metasilicate compound was completely dissolved in tap water before marinated with samples. Except for tap water and sodium metasili cate, no other ingredients were added to the fillets in this study. The treated fillets were weighed and packaged in Cryovac 2.0 trays (Type CS978, Mulinix package Inc., Fort Wayne, IN ). Two fillets were placed into each tray and stored at 4C for 9 days For each treatment, two packages were randomly collected on 0, 1, 3, 5, 6, 7 and 9 days and the samples were analyzed the marination yield, pH, the total psychrotrophic counts, water holding capacity, purge loss, cooking yield, color, shear force and sensory evaluation. The marination yield (%) was calculated using the following equation: Marination Yield (%) =100* W1/W2 (3 5) W2 represents weight of fillets premarination, g W1 represents weight of fillets post marination, g pH Analysis The pH value was determined immediately after completing microbiology analysis. pH value was measured using pH Meter (Accumet Basic AB15 pH Meter, Model no. SA 520, Fisher Scientific, Fair Lawn, NJ). Prior to analysis of pH for each treatment, the pH meter was calibrat ed using pH buffers 4.00 (SB101500, Fisher Scientific, Fair Lawn, NJ) and 7.00 (SB 107 500, Fisher Scientific, Fair Lawn, NJ). The probe was placed into

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56 the sample homogenate and allowed to equilibrate for one minute before the pH reading was recorded. Al l pH readings were performed in duplicates. Water Holding Capacity Analyses Water holding capacity with sodium chloride. The water holding capacity method described by zhuang et al. (2008) was conducted in this study. The treated fillets were minced with a food processor (Braun Multiquick Hand Blender, Model: Mr400 HC, Type 4185, Lighthouse Point, FL). Ten gram minced samples were placed into a 50 ml tube containing 15 ml 0.6 M sodium chlorine solution and vortexed (Votex Geniz 2TM Cat. No. 12812 Model G 250, Fisher scientific, McGaw, IL) for 1 minute per tube to insure even distribution. The tubes were placed in a 4C cooler for 15 minutes prior to centrifuge. The centrifuge machine (Super speed Refrigerated Centrifuge, Sorvall RC5B, Beverly, MA) was tur ned on approximate one hour before measuring. The tubes were centrifuged at 3000 rpm at 4C for 15 minutes. The liquid was decanted, and the solid materi al was maintained in the tube. The weights of before and after centrifuged meat were recorded (Zhu ang et al., 2008) The samples were analyzed in duplicate. WHC (%) was determined by using the following equation: WHC % = 100 (W1 W2)/W3 (3 6) Where W1 represents solution added into the sample, g W2 represents solution removed after, g W3 represents the meat sample mass, g Water holding capacity with distilled water Except for addition of distilled water, the method was the same as described by zhuang et al. (2008). The t reated fillets were minced with a food processor (Braun Multiquick Hand Blender, Model:

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57 Mr400 HC, Type 4185, Lighthouse Point, FL). Ten gram minced samples were placed into a 50 ml tube containing 15 ml distilled water and vortexted (Votex Geniz 2TM Cat. No. 12812 Model G 250, Fisher scientific, M cGaw, IL) for 1 minute per tube to insur e even distribution. The tubes were placed in a 4C cooler for 15 minutes prior to centrifuge. The centrifuge machine (Super speed Refrigerated Centrifuge, Sorvall RC5B, Beverly, MA) was turned on approximate one hour before measuring. The tubes were centr ifuged at 3000 rpm at 4C for 15 minutes. The liquid was decanted, and the solid materi al was maintained in the tube. The weights of before and after centrifuged meat were recorded. The samples were analyzed in duplicate. WHC (%) was determined by using t he following equation: WHC % = 100 (W1 W2)/W3 (3 7) Where W1 represents solution added into the sample, g W2 represents solution removed after, g W3 represents the meat sample mass, g Purge Loss Analysis Purge loss included any liquid that was collect ed from the package tray. The w eights (Mettler Toledo scales, Model: MS 3001S 103, Switzerland) of liquid releas ed from fillets w ere recorded. Purge loss (%) was calculated by using the following equation: Purge loss (%) =100*W1/W2 (3 8) W1 represents liquid released from fillets, g W2 represents original fillet weight, g

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58 Cooking Yield Analysis Four fillets of each treatment were placed in a roasting pan. The roasting pan was covered with aluminum foil (Handi Foil; 18x 500, Wheeling, IL) to avoid mois ture lost from fillets. The fillets were baked in a conventional gas oven (Model: JGRS14 GE Built In Gas Oven) at 176.7C until internal temperature reached 74C which was monitored with copper constantan thermocoupl es attached to a potentiometer. The copper constantan thermocouples were inserted into the thickest part of the fillets before baking. The oven was preheated approximately 20 minutes until the oven temperature reached 176.7C. The weights (Mettler Toledo scales, Model: MS 3001S 103, Switzerland ) of the fillets were recorded before and after cooking, and cooking yield (%) was calculated using the following equation: Cooking yield % = 100* W2/W1 (3 9) W1 represents the weight before cooking, g W2 represents the weight after cooking, g Microbiological Analysis The treated fillets were analyzed for total psychrotrophic counts on each of the assigned sampling days. Twenty five gram fillets were aseptically cut and placed into a sterile stomacher bag ( Cat. NO. 400ml, Fisher Scientific, Pittsburgh, PA). The 225 ml sterile 0.1% peptone water (Cat. No. DFO1897174, Detroit, MI) was poured into the stomacher bag. The stomacher bag was manually massaged for two minutes to loose surface bacteria. One milliliter of homogenate aliquot from stomacher bag wa s transferred into a test tube containing 9 ml sterile 0.1% peptone water. Five tubes were employed for each treatment from 102 to 106 serial dilutions. The contents of tubes were mixed using vortex (Votex Geniz 2TM Cat. No. 12812 Model G 250, Fisher

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59 scientific, McGaw, IL) for 15 seconds to insure that the bacteria were evenly distributed. Approximately 0.1 mL aliquot of the diluted sample homogenate from each serial dilution was aseptically transferred into sterile disposable 100 x 20mm Petri plates (Cat. No. 08757 103C, Fisher Scientific, Suwanee, GA) that contained prepoured hardened Tryptic Soy Agar (No.1010617, MP Biomedicals, Inc., Solon, OH). The homogenate was spread on the plates using a sterile glass hockey stick. The stick was sterilized wi th 70% ethanol and flamed before spreading. The plates were incubated aerobically at 7C for 10 days for total psychrotrophic counts (Hamm, 2001). Microbiological counts were expressed as Logarithmic Colony Forming Units per grams (Log CFU/g). The counts w ere recorded when 25250 colonies were on the plate. All plates were done in duplicates. Objective Color Measurement The color of raw and cooked fillets was measured with the Hunter MiniScan XE plus colorimeter (Hunter Associates Laboratory Inc Reston, VA). The colorimeter was calibrated with a standard black tile and white tile as recommended by manufacturer. Fillets (two fillets per package) were measured at a total of four different locations for L*, a* and b* values. The instrumental color of L* a* b color spectrum was recorded, where L* represents the total light reflected on a scale ranging from 0 = black to 100 = white, a* represents the amount of red (positive values) and green (negative values), and b value represents the amount of yellow (positive values) and blue (negative values). All color measurements were performed in duplicates. Warner Bratzler Shear Force Analysis The 1.0 cm cooked strips were employed for Instron shear force. The cooked 1.0 cm strips were covered with aluminum foil, and stored at 4C for 18 hours prior to

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60 Instron measurements. Texture measurements were conducted as described by Lyon and Lyon (1991). Each strip was oriented in the Warner Bratzler shear attachment (Type D. D., Catalog no. 2830002) which was attached to the Model 1011 Instron Texture machine (Model 1011, Instron Corporation, Norwood, MH). The speed of cross head was 200 mm/min with a 50 kg load cell. The full scale range was 10 kg (Williams and Phillips 1998). The Warner Bratzler shear force values were recorded in kilograms. Five values were obtained from each treatment. All treatments were done in duplicates. Sensory Evaluation Cooked meat was sectioned for sensory and instrumental texture measurements as described by Lyon et al., (2005) with some minor changes. The fillets were cut into 2 to 3 cubic cm wide strips paralleled with the direction of fiber. One strip was separated into three or four cubic cm for sensory evaluation, and another strip was used to determine instrumental texture. The cubes were trimmed into uniform size. Two cubes of each treatment were placed into a prewarmed container to keep the serving temperature at approximate 55C. The serving containers were labeled with one digit numbers. The sensory evaluation was performed in t he Meat Laboratory sensory room equipped with eleven separated booths. Each booth was equipped with a ceiling lighting system with red, white, blue, or yellow lighting as needed (Williams and Phillips, 1998). The eight point hedonic scoring scales were employed for juiciness, chicken flavor intensity, and tenderness evaluation, where 8 represents extremely juicy, extremely intense and extremely tender, 7 represents very juicy, very intense, and very tender, 6 represents moderately juicy, moderately intense and moderately tender, 5 represents slightly juicy, slight intense and slight tender, 4 represents slightly dry, slight bland and slight tough, 3 represents moderately dry, moderately bland and moderately tough, 2

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61 represents very dry, very bland and very tough, and 1 represents extremely dry, extremely bland and extremely tough. A six point scale was utilized for off flavor evaluation. 6 represents none detected, 5 represents threshold; barely detected, 4 represents slight off flavor, 3 represents moder ate off flavor, 2 represents strong off flavor and 1 represents extreme off flavor. Statistical Analysis The experiment was arranged in a complete randomized 5 (treatments) x7 (sampling days) factorial design and was replicated two times. Data were analyz ed using the GLM procedure of SAS (SAS Institute, 2002) by generating an analysis of variance (ANOVA). The model included the main effects of antimicrobial treatment, storage day, and treatment by day interaction. Data were reanalyzed within a day and within a treatment. Comparisons among means were performed using SAS Duncan Multiple Range test of the Statistical Analysis System. Treatments effects and differences were considered significantly when P < 0.05. The MEANS procedure was employed to analyze day and treatment.

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62 CHAPTER 4 RESULTS AND DISCUSSI ON Phase I. Preliminary Study: Application Method and Evaluation of Sodium Metasilicate at Approved Level for Poultry Meat Experiment 1 Marination yield analysis The fillets treated with 1% and 2% sodium m etasilicate had slightly higher observed marination yield s than control treatment (Figure 4 1). The data suggested that sodium metasilicate had ability to bind more water under still marination conditions. pH and cooking yield analyses The data demonstrat ed that meat pH values increased as the concentration of sodium metasilicate levels increased. The pH value of control fillets and fillets treated with 1% and 2% sodium metasilicate were 6.05, 6.65 and 6.85, respectively (Figure 4 2). This is also true for the marinade solutions wherein pH increased with increased sodium m etasilicate levels (Figure 4 3). Control fillets and fillets treated with 2% sodium metasilicate had higher cooking yield s than fillets treated with 1% sodium metasilicate (Figure 4 4). T he higher cooking yield for 2% may due to the water binding capacity of sodium metasilicate. Microbiological analysis The total psychrotrophic counts (TPC) for all treatments had too numerous to count ( TNTC) for dilution of 10 1 and 10 2 on day 0 (Tabl e 4 1). The results indicated that fillets treated with 2% sodium metasilicate had less observed psychrotrophic counts, when compared to control fillets and fillets treated with 1% sodium metasilicate.

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63 Objective color measurement Raw f illet c olor On day 0, the L* (lightness ) values of raw fillets treated with 0% (Control, tap water), 1% and 2% sodium metasilicate solution were 58.48, 63.35, and 61.20, respectively (Table 4 2). Based on International Commission on Illumination (CIE) lightness values for c hicken breast meat, normal L* values (lightness) of fillets are between 48 and 53, L* values of fillets less than 46 are considered dark, and L* values of fillets greater than 53 are considered light for chi cken meat (Qiao et al., 2002 ). L* values higher t han 60 are considered Pale, Soft, Exudative (PSE) (Van Laack et al., 2000). Qiao et al. (2002) also reported the color change of three groups of breast meat samples after overnight storage at 4C The samples were chopped prior to measure, the L*, a* and b* values of dark ground meat were 57.83, 5.01, and 9.05, respectively. The L*, a* and b* values of normal ground meat were 62.07, 4.38 and 9.68, respectively. And the L*, a* and b* values of light ground meat were 64.34, 3.75 and 9.55, respectively. In th is preliminary study, the sodium metasilicate treated samples were lighter (P > 0.05) than the control treatment. The control fillets were redder (P > 0.05) than sodium metasilicate treatments on day 0 (Table 4 2). T he control fillets were less yellow (P > 0.05) than fillets treated with sodium metasilicate on day 0. These results revealed that sodium metasilicate treatments had higher L*, less a*, and higher b* values (P > 0.05), when compared to the control fillets (Table 4 2). Cooked f illet c olor The data revealed that all treatments had similar (P > 0.05) a* and b* values (Table 4 2). The control fillets had lighter (P < 0.05) cooked meat color than fillets treated 2% sodium metasilicate, and darker (P < 0.05) than fillets treated with 1% sodium metasilicate.

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64 Sensory evaluation and warner bratzler shear force analyses No significant differences (P > 0.05) were observed among treatments regarding juiciness chicken flavor intensity, tenderness and off flavor sensory characteristics ( Table 4 3). All the treatments had similar (P > 0.05) Warner Bratzler shear force (Table 4 3) The data revealed that these parameters were not influenced by the concentration of sodium metasilicate in this preliminary study. Experiment 2 In this preliminary study, the sampling days were 0, 1, 3, and 6. However, Off odor, slim formation and surface discoloration were detected in the samples on day 6, therefore, collecting data for sensory evaluation, instrumental texture, cooked meat color and cooking yield were discontinued after day 3. Marination yield analysis The control fillets and fillets treated with 2% sodium metasilicate had slightly higher marination yield when compared to f illets treated with 1% sodium metasilicate after marinated (Figure 4 5). p H analysis As con centration of sodium metasilicate increased, the pH of meat increased (Table 4 4 ). T he pH value of 2% sodium metasilicate treatment was significantly higher (P < 0.05) than the control and 1% sodium metasilicate treatments over 6 days storage. As storage time increased, the meat pH values of control treatment were similar (P > 0.05) over storage periods. The pH values of 1% sodium metasilicate treatment decreased over storage ti me and 2% sodium metasilicate treatment decreased on day 6 when compared to pH values of day 0.

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65 Cooking yield analysis Except for day 3, the cooking yield increased as the concentration of sodium metasilicate increased (Figure 4 6). The cooking yield for 2% sodium metasilicate treatment was higher than the control and 1% sodium metasilicate treatments through 3 days storage. T he cooking yields for control and 2% sodium metasilicate treatments slightly fluctuated (first decreased then increased) over storage time. Microbiological analysis The total psychrotrophic counts increased for all treatments as storage time increased (Table 4 5 ). Except for day 3, the fillets treated with sodium metasilicate had significantly lower (P < 0.05) total psychrotrophic counts through 6 days storage, when compared to control treatment. No signific ant differences (P > 0.05) in to tal psychrotrophic counts were detected between fillets treated with 1% and 2% sodium metasilicate through 3 days storage. On day 6, the psychrotrophic counts for all tre atments had reached or exceeded 7 lo g cfu/g, and all s amples had produced slime forma tion and off odor development. Objective color measurement Raw f illet c olor The L* (lightness) values for control fillets were similar (P > 0.05) with fillets treated with 1% and 2% s odium metasilicate on day 0 and day 1 (Table 4 6 ). On day 3, the control fillets were significantly darker (P < 0.05) than fillets treated with sodium metasilicate. The fillets treated with 1% sodium metasilicate had lower (P > 0.05) L* values on day 0 when compared with day 1 and day 3 The c ontrol fillets had lower (P < 0.05) a* (redness) values than fillets treated with 1% sodium metasilicate on day 0. The fillets for all treatments had similar (P > 0.05) a* values on day 1 and day 3.

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66 The control fillets had lower (P < 0.05) b* (yellowness) values than fillets treated with 2% sodium metasilicate on day 1. The fillets for all treatments were similar (P > 0.05) on day 0 and day 3. Cooked f illet c olor The fillets treated with 1% sodium metasilicate were darker (P < 0.05) than control fillets on day 0 (Table 47) The fillets for all treatments were similar L* (lightness) on day 0 and day 3. The control fillets were less red (P < 0.05) than fillets treated with 1% and 2% sodium metasilicate on day 0. The control fillets were redder (P < 0.05) t han fillets treated with 2% sodium metasilicate on day 1. On day 3, all fillets had similar (P > 0.05) redness. The fillets treated with 1% sodium metasilicate were yellower than control fillets and fillets treated with 2% sodium metasilicate. All fillets were similar (P < 0.05) yellowness on day 1 and day 3 Warner bratzler shear force analysis The Warner Bratzler shear force value for all treatments fillets were less than 3.62, which were indicative of very tender meat (Table 4 8 ). The Warner Bratzler s hear force values were similar (P > 0.05) on day 0 and day 1 for all treatments. The fillets treated with 2% sodium metasilicate had higher (P < 0.05) Warner Bratzler shear force values, when compared to control fillets and fillets treated with 1% sodium m etasilicate. Sensory evaluation On day 0, the fillets treated with 1% and 2% sodium metasilicate were significantly juicier (P < 0.05) than control fillets (Table 4 9 ). On day 1, all fillets had similar (P > 0.05) juiciness. On day 3, the fillets treated with 1% sodium metasilicate were significantly juicer (P < 0.05) than fillets treated with 2% sodium metasilicate. As storage time increased, only fillets treated with 2% sodium metasilicate decreased in juiciness

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67 over 3 days storage, all other treatment s fillets had similar (P > 0.05) juiciness through 3 days storage. Chicken flavor intensity was similar (P > 0.05) for all treatments through 3 days storage. The control fillets on day 3 had significantly (P < 0.05) stronger chic ken flavor intensity than day 1, all other treatment fillets had similar ( P > 0.05) chicken flavor intensity through 3 days storage. Based on the responses of the panelists, overall tenderness varied from moderately tender (6.14) to extremely tender (7.63). There was no significa nt difference (P > 0.05) among treatments on individual sampling days. The sensory data indicated that the panelists barely (score of 5) or did not detect (score of 6) off flavor for all treatments. The effectiveness of sodium metasilicate at USDA app roved level up to 2% marinade solution did not extend shelf life, maintain the raw meat color discoloration, and increased cooking yield and marination yield. However, the data were inconsistent between the two preliminary experiments. Therefore, further i nvestigation was necessary to determine the effectiveness of sodium metasilicate at the USDA approved levels and elevated levels on shelf life and meat quality Phase II. Preliminary Study: Determination of the Effectiveness of Sodium Metasilicate at USDA Approved and Elevated Levels in a Shelf Life Study Marination Yield Analysis The fillets treated with sodium metasilicate had higher marination yields than control fillets (Figure 4 7). Except for fillets treated with 2% sodium metasilicate, the marination yield for all treatments slightly increased, as the concentration of sodium metasilicate increased.

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68 pH Analysis In general, the pH of poultry meat increased, as the concentration levels of sodium metasilicate increased (Table 4 10). The pH values of fillets treated with 4% sodium metasilicate were significantly higher (P < 0.05) over 9 storage days when compared with control fillets and fillets treated with 1% sodium metasilicate. The pH values for 1%, 2%, 3%, and 4% sodium metasilicate marinade sol ution s were 12.42, 12.58, 12.75, and 12.83, respectively, these values were approximate 5 pH units higher tha n control solution which was 7.71 (Figure 48). The fillets treated with sodium metasilicate were expected to be more alkaline than control fillets However, there was no significant dif ference (P > 0.05) for pH values between control fillets and fillets treated with 1% sodium metasilicate through 7 days storage. Except for d ay 7, the pH values of fillets treated with 3% and 4% sodium metasilicate were similar (P > 0.05) over 9 days storage. Except for fillets treated with 4% sodium metasilicate, all pH values of fillets among treatments were similar (P > 0.05) on day 0. Water Holding Capacity Analyse s Water holding capacity with sodium chloride The results for water holding capacity (WHC) measured with the standard method (sodium chloride) are shown in T able 4 11. There were no significant differences in WHC among treat ments on days 0 through day 5. The WHC for all sodium metasilicate treatments wer e consistently higher (P > 0.05) when compared to control treatment. On day 7, the WHC of fillets treated with 1% and 4% sodium metasilicate were significantly higher (P < 0.05), when compared to control fillets, and no difference (P > 0.05) was detected among fillets treated with 1%, 2% and 3% sodium metasilicate. On day 9, the WHC of fillets treated with 1% and 2% sodium metasilicate were significantly higher (P

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69 > 0.05), when compared to control fillets, and were similar (P > 0.05) with fillets treated w ith 3% and 4% sodium metasilicate. Except for the WHC of fillets treated with 3% sodium metasilicate decreasing over storage time, the WHC of fillets for all treatments were similar (P > 0.05) through 9 days storage. Water h olding c apacity w ith d istilled w ater The WHC percentages for all treatments were similar (P > 0.05) on day 3 (Table 4 12). On day 5, the WHC values for fillets treated with 1% sodium metasilicate were significantly higher (P < 0.05), when compared to control fillets, and similar (P > 0.05) among all other treatments. On day 7, the WHC values for fillets treated with 2% sodium m etasilicate were significantly lower (P < 0.05) when compared to control fillets. On day 9, the WHC values for fillets treated with 3% and 4% sodium metasilicate were significantly higher (P < 0.05), when compared to control fillets and fillets treated with 1% sodium metasilicate. Various methods have been developed or used to estimate meat WHC. For example, drip loss, cooking yield, filter paper method and cent rifugal method (Zhuang, et al., 2008). In this experiment, the centrifuge method was used. The data (Table 4 11 and Table 4 12) indicated the uptake of added water by meat. The results of water uptake in T able 4 11 indicated the effective of combination of sodium metasilicate and sodium chloride. The results of water uptake in T able 4 12 indicated the effective ness of sodium metasilicate alone. The data suggested that sodium metasilicate had weak er WHC, when compared to sodium chloride. Cooking Yield Analysis A lthough there w as no statistical analysis of the data, the cooking yield values for fillets treated with 4% sodium metasilicate were higher than the remaining fillets

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70 treatments over 9 days storage (Figure 4 9). Except for fillets treated with 2% sodi um metasilicate on day 1, all fillets treated with sodium metasilicate had higher cooking yield value than control fillets through 7 days storage. On day 9, only fillets treated with 1% sodium metasilicate had slightly lower cooking yield s than control fil lets. The cooking yield values for all treatments on day 5 were lower than other sampling days The lower cooking yield values were attributed to the different storage method that was used on day 5. On day 5, all panelists were unavailable. Therefore, fill ets were stored in the freezer overnight, and analyzed on the next day. Freezing treatment could alter the spatial arrangement of the fibrillar network of meat, and would decrease the water holding capacity. Therefore, much m ore liquid from meat would be r elease d during cooking, when compared to unfrozen meat. Microbiological Analysis In general, as storage time increased, the total psychrotrophic counts increased for all treatments (Table 4 13). The fillets treated with 4% sodium metasilicate had signific antly lower (P < 0.05) psychrotrophic counts through 9 days storage, when compared to control fillets and fillets treated with 1% and 2% sodium metasilicate. Except for day 3, the fillets treated with 3% sodium metasilicate had significantly lower (P < 0.0 5) psychrotrophic counts than control fillets over 9 days storage. The total psychrotrophic counts for control fillet s and fillets treated with 1% sodium metasilicate had similar (P > 0.05) counts through 7 days storage. No microbial growth on plates were detected for fillets treated with 3% and 4% sodium metasilicate on day 0 and day 1 at highest dilution plated, which was 102. In general, off odor was detected when total psychrotrophic counts reached 7 to 8 log cfu/g on meat surface and slime formation w as developed when total psychrotrophic counts were over 8 log cfu/g. On day 7, the

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71 control fillets and fillets treated 1% and 2% sodium metasilicate were spoiled and the total psychrotrophic counts had reached 7 log10 cfu/g. On day 9, the fillets for all treatments were spoile d, and the total psychrotrophic counts for all treatments exceeded 8 log cfu/g. The data revealed that 1% and 2% sodium metasilicate treatments did no significantly retard the microbial growth. The fillets treated with 3% and 4% sodium metasilicate had significantly lower (P < 0.05) psychrotrophic counts through 7 days storage, when compared to control fillets. The data demonstrated that 3% and 4% sodium metasilicate treatment retarded the growth for psychrotrophs and increased the shelf life of the fillets at most to 2 additional days. Objective Color Measurement Raw fillet color L* value. The fillets for most treatments became darker as storage time increased (Table 4 14). On day 0, the fillets treated with 3% sodium metasilicate tr eatment were significantly darker (P < 0.05) than control f illets and similar (P > 0.05) with all other sodium metasilica te treatments. On day 5, the fillets treated with 1% and 2% sodium metasilicate were significantly darker (P < 0.05) than control fillets and similar (P > 0.05) to all other s odium metasilicate treatments. This effect was not observed at any other storage intervals. As storage time increased, the L* values for fillets treated with 1% sodium metasilicate were significantly lower (P < 0.05), when compared to day 0 and day 9. a* value. Except for day 0 and day 7, there was no significant difference (P > 0.05) for a* values (Table 4 15), when compared to control fillets and fillets treated with sodium metasilicate for other storage days. On day 0, the a* value for fillets treated with 1% sodium metasilicate were redder (P < 0.05) than fillets treated with 2% and 4%

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72 sodium metasilicate. On day 7, the fillets treated with 3% sodium metasilicate were significantly redder (P < 0.05) than control fillets and similar (P > 0.05) with other fillets tre ated with sodium metasilicate. The a* values t end to increase as storage time increased for all treatments. M yoglobin is responsible for the majority of the red color, as storage time increased, the liquid released from the fillets increased, and the concentration of myoglobin on the surface of meat increased. b* value. The data indicated that b* values became greater as storage time increased (Table 4 16). The b* values for control fillets and fillets t reated with 4% sodium metasilicate had slightly changed as storage time increased. The fillets treated with 2%, 3% and 4% sodium metasilicate had similar (P > 0.05) b* values over 9 days storage. On day 0 and day 1, fillets treated with 1% sodium metasilic ate had significantly higher (P < 0.05) b* value than fillets treated with 4% sodium metasilicate. On day 9, fillets treated wi th 2% sodium metasilicate had lower (P < 0.05) b* value than control fillets and similar (P > 0.05) with all other treatments. Cooked fillet color L* value. The fillets treated with 2%, 3% and 4% had similar (P > 0.05) L* values as storage time increased (Table 4 17). Except for day 5 the control fillets and fillets treated with 1% and 2% sodium metasilicate had similar L* values (P > 0.0 5) through 9 days storage. As storage time increased, the L* values for t he control fillets and fillets treated with 1% sodium metasilicate decreased (P < 0.05) slightly on day 9. a* value. On d ay 0, the fillets treated with 1% sodium metasilicat e had higher a* value (P < 0.05), when compared to fillets treated with 2% and 4% sodium metasilicate (Table 418). On day 7, t he fillets treated with 3% sodium metasilicate had significantly

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73 higher (P < 0.05) a* value, when compared to control fillets Other fillets among treatments were similar (P > 0.05) for all sampling days. b* value. On day 0, control fillets and fillets treated with 1% sodium metasilicate had higher (P < 0.05) b* values than fillets treated with 2% and 4 % sodium metasilicate (Table 4 19). On day 1, the fillets treated with 1 % sodium metasilicate had greater (P < 0.05) b* value, when compared to fillets treated with 4% sodium metasilicate. On day 9, the fillets treated with 2% sodium metasilicate had lower b* values than control fillets. Fillets were similar (P > 0.05) for all other sampling days. Warner Bratzler Shear Force Analysis Except for day 1, shear force values were similar ( P > 0.05) for all treatments. On day 1, the control fillets and fillets treated with 3% sodium metasilicate had lower (P < 0.05) shear force values than fillets treated with 1% sodium metasilicate. The shear force values ranged from 1.18 kg to 2.03 kg for all treatments (Table 4 20). All samples in this study were very tender based on the tenderness descr i ption s of Lyon and Lyon (1991). Sensory Evaluation T he panelists rated all samples slightly juicy (5.17) to very juicy (7.00) (Table 4 21) Except for day 0, there was no significant difference in juiciness (P > 0.05) among all treatments through 7 days storage. On day 0, the fillets treated with 3% sodium metasilicate were juic i er (P < 0.05), when compared to all fillets treated with 2% and 4% sodium metasilicate. On day 9, the control fillets had similar (P >0.05) juiciness, when compared to sodium metasilicate treated fillets and the fillets treated with 2% and 3% sodium metasilicate were juicier ( P < 0.05) than fillets treated with 1% sodium metasilicate.

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74 Except for day 0, the panelists rated the chicken flavo r intensity for all treatments similar ( P > 0.05) for all storage days (Table 4 2 1). On day 0, t he fillets treated with 3% sodium metasilicate had greater (P < 0.05) chicken flavor intensity, when compared to all other treatments. Except for day 0, the panelists rated the tenderness of all treatments similar (P > 0.05) through 9 days storage (Table 4 22). The panelist s rated all samples moderately tender (6.33) to extremely tender (8.00). On day 0, the tenderness of fillets treated with 3% sodium metasilicate were significantly higher (P < 0.05) than all other treatments. The fillets treated with 3% sodium metasilicate had a higher tenderness score on day 0 than on all other sampling days. The panelists rated all treatments similar for offflavor (P > 0.05) through 9 days storage (Table 422) T he data indicated that the panelists barely detected (score of 5) or did not detect ed (score of 6) off flavo r development for all treatments Phase III. Investigation the Effectiveness of Sodium Metasilicate at the USDA Approved and Elevated Level s on An timicrobial Sensory Chemical and Physical Characteristics of Fresh Chicken Breast Meat and Stored at 4C for 9 Days Marination yield Analysis In general, the marination yield increased, as the concentration levels increased (Figure 410). T he fillets tr eated with 1% sodium metasilicate had slightly higher marination yield than the other sodium metasilicate treatments In this study, all sodium metasilicate treatments had slightly higher marination yield than control treatment. pH Analysis The fillets tr eated with 3% and 4% sodium metasilicate had significantly higher (P < 0.05) pH values than the control fillets and fillets treated with 1% sodium metasili cate over 9 days storage (Table 423). Except for day 3, the pH values were similar (P >

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75 0.05) between the control fillets and fillets treated with 1% sodium metasilicat e over 9 days storage. Except for d ay 7, the pH values were similar (P > 0.05) between fillets treated with 2% and 3% sodium met asilicate. There was a slight decrease in trends for treatments that contained sodium metasilicate over storage time. This may be due to the production of various acid compounds by s poilage bacteria (Ruiz, 2007). The microorganisms initially metabolized the glucose as energy, and later broke down small compounds, such as amino acid. The metabolic process es resulted in the muscle meat pH value decreasing. Liu et al. (2004) also reported that the pH values declined through storage times The complex biochemical reactions could lead to decrease in pH values. Decreasin g (P < 0.05) in pH values were observed for 2% sodium metasilicate treatment on days 6 and 7, and for 3% and 4% sodium metasilicate treatments on day 9, when compared to day 0 pH values. Water Holding Capacity Analyse s Water holding capacity with sodium chloride. The WHC values were expected to increase, as the pH values of fillets increased. In this study, the WHC of fillets measured with sodium chloride had no significant difference (P > 0.05) among treatments and over storage periods (Table 4 24). Wa ter holding capacity with distilled water. On day 1, the fillets treated with 3% sodium metasilicate had significantly higher (P < 0.05) WHC than fillets treated with 1% sodium metasilicate (Table 4 24). On day 3, the fillets treated with 1% and 3% sodium metasilicate had significantly higher (P < 0.05) WHC values than control fillets. On day 7, the fillets treated with 4% sodium metasilicate had significantly higher (P < 0.05) values than other fillets treated with sodium

PAGE 76

76 metasilicate. Except for day 3, the values for fillets treated with 1% sodium metasilicate treatments had similar (P > 0.05) with control fillets. Purge Loss Analysis In general, as storage time increased, the purge loss percentages for all treatments increased (Table 4 25). The purge loss values were similar (P > 0.05) among all treatments for 7 days storage. On day 9, the purge loss of 3% and 4% sodium metasilicate treatments were significantly lower (P < 0.05) than all other treatments. Cooking Yield Analysis On day 0, the cooking yield s for fillets treated with 3% sodium metasilicate were significantly higher (P < 0.05), when compared to all other treatments (Table 4 26). On day 1, the cooking yields for all treatments were similar (P > 0.05). On day 3, the cooking yields for fillets treated with 3% and 4% sodium metasilicate were higher (P < 0.05) than control fillets and fillets treated with 1% sodium metasilicate. On day 5, the cooking yield for fillets treated with 3% and 4% sodium metasilicate were higher (P < 0.05) than all other treatments. On day 6, the cooking yields for fillets treated with 3% were higher (P < 0.05) than control fillets and fillets treated with 4% sodium metasilicate. The results indicated that the cooking yields for fillets treated with 3% sodium m etasilicat e were higher through all storage days except for day 0. Microbiological Analysis In general, the total psychrotrophic counts increased as the storage time increased for all treatments (Table 4 27). When the concentrations of antimicrobial s increased, the effectiveness of its properties increased. The total psychrotrophic counts for fillets treated with 4% sodium metasilicate treatment were significantly lower (P < 0.05) than

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77 control fillets and fillets treated with 1% sodium metasilicate through 9 days st orage. Except for day 0, there were no significant difference (P > 0.05) among control fillets and fillets treated with 1% and 2% sodium metasilicate through 9 days storage. Except for day 7, there was no significant difference (P > 0.05) among fillets treated with 3% and 4% sodium m etasilicate over storage time. Except for fillets treated with 2% sodium metasilicate, the total psychrotrophic counts were similar (P > 0.05) for all treatments, when compared to the initial day and day 1. From day 1 to day 5, the growth rate of microbial accelerated for all treatments. On day 5, the control fillets and the fillets treated 1% and 2% sodium metasilicate reached 8 log cfu/g, therefore, the samples were spoiled. On day 6, the fillets for all treatments were spoiled. The results indicated that the 3% and 4% sodium metasilicate treatments were effective to extend two additional days for shelf life, when compared to control 1% and 2% treatment s. When the means of the two trials were compared in phase II I study, the t otal psychrotrophic counts for the two trial s were similar (P > 0.05) on day 0, but after day 3, th e total psychrotrophic counts for the two trials were higher by an average of 1 2 log cfu/g units than preliminary study through 7 days storage. Results fr om this study suggested that the initial population of total psychrotrophic organisms w as similar, but the storage condition, handling of samples and incubation conditions may have contributed to the acceleration of microbial growth. Objective Color Measurement Raw fillet color. L* value. On the initial day, the color of fillets treated with 2% sodium metasilicate were darker ( P < 0.0 5), when compared to control fillets, and similar with t he remaining sodium metasilicate treatments (Table 4 28) On day 3, the color of fillets treated with

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78 2% and 4% sodium metasilicate were darker (P < 0.05), when compared to control fillets, and similar (P > 0.05) to other fillets treated with sodium metasilicate. On day 6, the color of fillets treated with 3% sodium metasilicate were lighter (P < 0.05) than control fillets and no significant difference s (P > 0.05) were observed among all other fillets treated with sodium metasilicate. On day 7, the fillets treated with 2%, 3% and 4% sodium metasilicate were lighter (P < 0.05) than control fillets and no significant difference s (P > 0.05) were observed between control fillets and fillets treated with 1% sodium metasilicate. On day 9, the fillets treated with 4% sodium metasilicate had higher L* values (P < 0.05) than fillets treated with 1% sodium metasilicate. The control fillets and fillets treated with 1% sodium metasilicate had similar (P > 0.05) over 9 storage days. The remaining fillets treated with sodium metasilicate were similar color over 9 storage days. The data in dicated that the L* value s for all treatments decreased as storage time increased, when compared with day 0 and day 9. However the greatest difference in L* values change was observed in the control fillets. T he L* values for control fillets were similar (P > 0.05) through 3 days storage. From day 1 to day 3, the fillets treated with 1% sodium metasilicate increased 3 log units for total psychrotrophic counts The significantly L* values change for fillets treated with 1% sodium metasilicate may be due to the drastic microbial growth after day 3. It was possible that the onset of spoilage in the meat was on day 5 (control, 1%, and 2%) and on day 6 (3% and 4%). The bacteria may have produce d pigments on the meat surface. The data indicated that t he microbial counts increased 2 log units from day 3 to day 5, which might also explain the L* values of control fillets changing after day 3. Therefore, sodium metasilicate could cause color

PAGE 79

79 of fillets to become darker on the first three days storage, and a lso could maintain the L* values for fillet s treated with 3% and 4% sodium metasilicate treatments after day 3. a* values: The fillets treated with sodium metasilicate had similar (P > 0.05) a* values, when compared to control fillets over 6 days storage (Table 4 2 9) After day 6, the control fillets were redder (P < 0.05) than all fillets treated with sodium metasilicate. As storage time increased, the control fillets became redder. This may be explained that as the storage time increased, the purge loss increased and the concentration of myoglobin on the surface of the meat increased. b* values: A s storage time increased, the b* values increased (Table 4 30). Except for day 0 and day 9, the b* values for fillets treated with 3% and 4% sodium metasilicate were low er than ( P < 0.05) than control fillets through storage days. The results demonstrated that the sodium metasilicate could retard the yellowness development, when compared to control fillets. Cooked fillet color L* value. On day 0, the control fillets and fillets treated with 1% sodium metasilicate were lighter (P < 0.05), when compared to fillets treated with 4% sodium metasilicate, and were similar (P > 0.05) with remaining fillets (Table 4 31). On day 1, the control fillets and fillets treated with 1% sodium metasilicate were lighter (P < 0.05), when compared with remaining fillets treated with sodium metasilicate. On day 5, the control fillets and fillets treated with 4% sodium metasilicate were darker (P < 0.05), when compared to fillets treated wit h 3% sodium metasilicate. a* value. The a* values w ere similar among control fillets and fillets treated with 1% sodium metasilicate through 6 days storage (Table 4 31). Also the a* values were similar (P > 0.05) among fillets treated with 2% ,3% and 4% s odium metas ilicate

PAGE 80

80 through 6 days storage. The fillets treated with 4% sodium metasilicate were redder (P < 0.05) than control fillets on day 0 and day 3. b* values. Except for day 5, the b* values were similar (P > 0.05) for control fillets and fillets treated with 1% sodium metasilicate through 6 days storage (Table 4 31). Also the b* values were similar (P > 0.05) among fillets treated with 2%, 3% and 4% sodium metasilicate through 6 days storage. Several studies reported that there was significantly negative correlation between the raw breast meat lightness ( L*) and pH value (Allen et al., 1998). Allen et al. (1998) reported that samples marinated with a solution containing 3% sodium tripolyphosphate (STPP) and 7% sodium chloride had significantly hi gher L* (lightness) values and lower a* (redness) values and b* (yellowness) values ,when compared to control samples. Some researchers reported that samples marinated with 1% and 2% trisodium phosphate had lower L* and higher a* values. Some studies repor ted that no color differences were observed (P > 0.05) after meat was treated with sodium tripolyphosphate (STPP). Some results reported that still marination with sodium polyphosphate solution had higher L* (lightness) values for raw meat color. All of these studies reported that the color changed after the meat was marinated with an alkaline solution. Warner Bratzler Shear Force Analysis Except day 1, no significant difference s for Warner Bratzler shear force values were detected among all treatments through 6 days storage (Table 4 32). On day 1, the control fillets and fillets treated with 4% sodium metasilicate were lower (P < 0.05), when compared to fillets treated with 1%, 2% and 3% sodium metasilicate. Lyon and Lyon (1991) reported that Warner Bratz ler shear force values less than 3.62 kg for

PAGE 81

81 chicken breast meat were indicative of very tender meat. The Warner Bratzler shear force values for all treatments ranged from 1.82 kg to 2.86 kg, which was indicative of very tender breast meat. The corresponding panelist scores were moderately tender to extremely tender meat. Sensory Evaluation Juiciness On day 0, the fillets treated with 3% and 4% sodium metas ilicate were juic i er (P < 0.05) when compared to the other treatments (Table 4 33). Based on the responses of the panelists, on day 0, fillets treated with 1% sodium metasilicate were slight dry on day 0. The control fillets and fillets treated with1% and 2% sodium metasilicate were slight dry to slight dry slight juicy. The fillets treated with 3% and 4% sodium metasilicate were moderately juicy Except for day 0, fillets for all treatments had similar (P > 0.05) juiciness over 6 day storage. As storage time increased, the fillets treated with 3% and 4% sodium metasilicate were similar ( P > 0.05) over 6 days storage. Chicken flavor intensity Except for day 0, the chicken flavor intensity for all treatments was similar (P > 0.05) through 6 days storage (Table 4 34). On day 0, the chicken flavor intensity for fillets treated with 3% sodium metasilicate were higher (P < 0.05), when compared to fillets treated with 1% sodium metasilicate, and were similar ( P > 0.05) with control fillets and other fillets treated with sodium metasilicate. Tenderness Except for day 1, the tenderness of fillet s in all treatments was similar (P > 0.05) through 6 days storage (Table 4 -34). On day 1, the fillets treated with 2% sodium

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82 metasilicate were more tender (P < 0.05) when compared to control fillets. Lyon and Lyon (1991) reported that there is a relationsh ip between the objective shear forces values and subjective sensory tests for tenderness in broiler chicken breast meat. Off flavor None of the treatments developed off flavor during 6 days of storage. All values were on the range of barely detected (sc ore of 5) to none detected (score of 6).

PAGE 83

83 Figure 4 1. Marination yield percentages for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C on day 0 Figure 4 2. pH value for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C on day 0

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84 Figure 4 3. pH of marinade solutions for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C on day 0 Figure 4 4. Cooking yield percentages for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C on day 0

PAGE 85

85 Table 4 1. Total psychrotrophic counts for boneless and skinless broiler chicken breast meat marinated wit h sodium metasilicate and stored at 4C on day 0 Treatment Dilution A1 A2 B1 B2 Control 0.10 TNTC TNTC TNTC TNTC 0.01 250 252 377 332 1% SMS 0.10 TNTC TNTC TNTC TNTC 0.01 291 TNTC TNTC TNTC 2% SMS 0.10 TNTC TNTC TNTC TNTC 0.01 TNTC TNTC 84 86 Colony numbers between 25250 was counted; TNTC = C olonies over 250 and it was too numerous to count; SMS = Sodium metasilicate. Table 4 2. Meat color measurement for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C on day 0 Attribute Treatment Raw L* Raw a* Raw b* Cooked L* Cooked a* Cooked b* Control 58.48 7.27 14.62 82.15 b 2.03 17.2 0 1% SMS 63.35 5.73 16.03 84.45 a 1.62 16.61 2% SMS 61.20 6.51 17.22 79.59 c 2.03 16.34 SEM 2.52 2.32 1.73 1.06 0.50 1.21 ac M eans in same column with different superscripts differ significantly (P < 0.05); n = 3 values per mean; SMS = Sodium metasilicate; SEM = Standard error of the mean.

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86 Table 4 3. Sensory evaluation and Warner Bratzler shear force for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C on day 0 Attribute Treatment Juiciness Chicken flavor Intensity Tenderness off flavor Warner Bratzler shear force, Kg Control 5.00 6.50 5.50 5.50 6.41 1% SMS 4.00 6.00 5.50 4.50 6.06 2% SMS 4.00 6.00 5.00 4.50 7.41 SEM 1.15 0.91 0.58 0.71 1.48 n = 7 values per mean; SMS = Sodium metasilicate; SEM = Standard error of the mean. Figure 4 5. Marination yield percentages for boneless and skinless broiler ch icken breast meat marinated with sodium metasilicate and stored at 4C for 6 day s

PAGE 87

87 Table 4 4 pH measurement for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 6 days Storage time Attribute Treatment d 0 d 1 d 3 d 6 SEM pH Control 6.00 c,x 6.15 b,x 6.01 c,x 6.03 b,x 0.1 0 1% SMS 6.46 b,x 6.38 b,x 6.38 b,x 5.98 b,y 0.10 2% SMS 6.84 a,xy 7.04 a,x 6.62 a,yz 6.39 a,z 0.11 SEM 0.08 0.14 0.07 0.11 ac M eans in same column with different superscripts differ significantly (P < 0.05); x z M eans in same row with different superscripts differ significantly (P < 0.05); n = 3 values per mean ; SMS = Sodium metasilicate; SEM = Standard error of the mean. Figure 46. Cooking yield percentages for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 6 days

PAGE 88

88 Table 45. Total psychrotrophic counts for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 6 days Storage time Attribute Treatment d 0 d 1 d 3 d 6 SEM TPC, log cfu/g Control 6.55 a,y 6.43 a,y 6.77 a,y 8.82 a,x 0.23 1% SMS 5.02 b,z 5.34 b,z 6.57 a,y 7.53 c,w 0.29 2% SMS 4.51 b,z 5.35 b,y 6.73 a,x 8.24 b,w 0.15 SEM 0.17 0.21 0.32 0.18 ac M eans in same column with different superscripts differ significantly (P < 0.05); x z M eans in same row with different superscripts differ significantly (P < 0.05); n = 4 values per mean; TPC = Total psychrotrophic counts SMS = Sodium metasilicate; SEM = Standa rd error of the mean.

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89 T able 4 6. Objective raw meat color for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 3 days Storage time Attribute Treatment d 0 d 1 d 3 SEM L* Control 62.78 a,x 61 .19 a,x 59.70 b,x 2.85 1% SMS 55.60 a,y 65.00 a,x 61.62 a,x 1.94 2% SMS 57.06 a,x 61.69 a,x 62.28 a,x 3.66 SEM 4.44 2.27 0.67 a* Control 3.82 b,x 4.96 a,x 6.21 a,x 1.18 1% SMS 11.01 a,x 5.66 a,y 6.79 a,xy 2.09 2% SMS 6.99 ab,x 7.54 a,x 6.56 a,x 0.85 SE M 2.11 1.30 0.69 b* Control 12.48 a,y 14.99 b,y 18.90 a,x 1.55 1% SMS 16.70 a,x 15.31 ab,x 16.64 a,x 2.31 2% SMS 14.67 a,x 17.79 a,x 16.06 a,x 2.52 SEM 2.55 1.26 2.46 ab M eans in same column with different superscripts differ significantly (P < 0. 05); x y M eans in same row with different superscripts differ significantly (P < 0.05); n = 3 values per mean ; SMS = Sodium metasilicate; SEM = Standard error of the mean.

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90 Table 4 7. Objective cooked meat color for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 3 days Storage time Attribute Treatment d 0 d 1 d 3 SEM Cooked L* Control 84.25 a,x 84.03 a,x 79.62 a,y 1.61 1% SMS 80.76 b,y 84.13 a,x 79.95 a,y 1.45 2% SMS 82.53 ab,x 84.09 a,x 79.15 a,y 1.36 SEM 1.30 1.28 1.79 Cooked a* Control 1.15 b,y 2.03 a,x 1.85 a,x 0.33 1% SMS 2.62 a,x 1.74 ab,x 1.73 a,x 0.71 2% SMS 2.58 a,x 1.23 b,y 2.13 a,x 0.31 SEM 0.64 0.35 0.41 Cooked b* Control 16.07 b,x 16.38 a,x 15.79 a,x 0.68 1% SMS 18.96 a,x 17.04 a,xy 15.60 a,y 1.03 2% SMS 16.17 b,x 15.85 a,x 17.74 a,x 0.99 SEM 0.94 0.71 1.05 ab M eans in same column with different superscripts differ significantly (P < 0.05); x y M eans in same row with different superscripts differ significantly (P < 0.05); n = 3 values per mean; SMS = Sodium metasilicate; SEM = Standard error of the mean.

PAGE 91

91 Table 4 8. Warner Bratzler shear force f or boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 3 days Storag e time Attribute Treatment d 0 d 1 d 3 SEM Warner Bratzler shear force, Kg Control 1.65 a,y 2.07 a,x 1.68 b,y 2.27 1% SMS 1.83 a,x 2.25 a,x 1.68 b,x 0.47 2% SMS 1.63 a,x 2.20 a,x 2.12 a,x 0.36 SEM 0.33 0.51 0.24 ab M eans in same column with different su perscripts differ significantly (P < 0.05); x y M eans in same row with different superscripts differ significantly (P < 0.05); n = 6 values per mean; SMS = Sodium metasilicate; SEM = Standard error of the mean.

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92 Table 4 9 Panelist rating for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 3 days Storage time Attribute Treatment d 0 d 1 d 3 SEM Juiciness Control 5.88 b,x 5.29 a,x 5.20 ab,x 1.27 1% SMS 6.88 a,x 5.86 a,x 5.80 a,x 1.01 2% SMS 7.13 a,x 5.57 a,y 4.00 b,z 1.12 SEM 0.71 1.33 1.36 Chicken Flavor Control 5.75 a,xy 4.71 a,y 6.40 a,x 1.11 1% SMS 5.50 a,x 5.14 a,x 6.20 a,x 1.28 2% SMS 5.38 a,x 4.71 a,x 6.00 a,x 1.36 SEM 1.40 1.45 0.63 Tenderness Control 6.88 a,xy 6.14 a,y 7.20 a,x 0.83 1% SMS 7.13 a,x 6.57 a,x 7.20 a,x 0.98 2% SMS 7.63 a,x 6.86 a,x 7.60 a,x 0.81 SEM 0.86 1.04 0.67 Off flavor Control 5.75 a,x 5.29 a,x 6.00 a,x 0.80 1% SMS 5.88 a,x 5.71 a,x 6.00 a,x 0.36 2% SMS 5.63 a,x 5.57 a,x 6.00 a,x 0.80 SEM 0.70 0.90 0.0 0 ab M eans in same column with different superscripts differ significantly (P < 0.05); x y M eans in same row with different superscripts differ significantly (P < 0.05); n=10 values per mean; Sensory scale: Eight point sensory scale for juiciness, chick en flavor and tenderness where 8 = extremely juicy/intense/tender, 7 = very juicy/intense/tender, 6 = moderately juicy/intense/tender, 5 = slightly juicy/intense/tender, 4 = slightly dry/bland/tough, 3 = moderately dry/bland/tough, 2 = very dry/bland/tough, 1 = extremely dry/bland/tough. A six point scale for off flavor where 6 = none detected, 5 = threshold, barely detected, 4 = slight off flavor, 3 = moderate off flavor, 2 = strong off flavor, 1 = extreme off flavor; SMS = Sodium metasilicate; SEM = Stan dard error of the mean.

PAGE 93

93 Figure 4 7. Marination yield percentages for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days

PAGE 94

94 Table 4 10. pH measurement for boneless and skinless broiler chic ken breast meat marinated with sodium metasilicate and stored at 4C for 9 days Storage time Attribute Treatment 0 d 1 d 3 d 5 d 7 d 9 d SEM pH Control 6.55 b,x 6.56 c,x 6.30 c,z 6.45 c,y 6.39 d,y 6.22 c,z 0.11 1% SMS 6.86 b,x 6.69 c,xy 6.62 c,xy 6.65 c,xy 6.4 6 d,y 6.63 b,xy 0.10 2% SMS 7.07 b,x 6.91 b,x 6.91 ab,x 6.78 ab,x 6.70 c,x 6.75 b,x 0.16 3% SMS 7.36 ab,x 7.31 a,x 7.09 a,x 7.08 ab,x 6.89 b,x 6.90 ab,x 0.22 4% SMS 8.00 a,x 7.43 a,y 7.06 a,y 7.16 a,y 7.30 a,y 7.11 a,y 0.21 SEM 0.31 0.08 0.13 0.13 0.03 0.12 ac M eans in same column with different superscripts differ significantly (P < 0.05); x z M eans in same row with different superscripts differ significantly (P < 0.05); n = 4 values per mean; SMS = Sodium metasilicate; SEM = Standard error of the mean.

PAGE 95

9 5 Figure 4 8. Marinade solution of pH for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C on day 0

PAGE 96

96 Table 4 11. Water holding capacity percentages for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days : WHC with sodium chloride Storage time Attribute Treatment 0 d 1 d 3 d 5 d 7 d 9 d SEM WHC Na C l, % Control 117.14 a,x 131.52 a,x 92.77 a,x 142.99 a,x 134.99 c,x 119.02 b,x 32.69 1% SMS 148.86 a,x 14 2.98 a,x 142.78 a,x 148.52 a,x 147.41 ab,x 145.57 a,x 2.55 2% SMS 130.39 a,x 153.39 a,x 143.05 a,x 143.16 a,x 142.55 abc,x 142.13 a,x 13.43 3% SMS 147.03 a,w 144.08 a,xy 146.65 a,wx 143.72 a,y 140.16 bc,z 140.10 ab,z 2.84 4% SMS 144.55 a,x 149.82 a,x 148.51 a,x 152.33 a, x 152.19 a,x 139.33 ab,x 8.48 SEM 19.83 13.25 29.40 8.56 4.12 8.14 ac M eans in same column with different superscripts differ significantly (P < 0.05); wz M eans in same row with different superscripts differ significantly (P < 0.05); n = 2 values per m ean ; WHC = Water holding capacity; NaCl = Sodium chloride; SMS = Sodium metasilicate; SEM = Standard error of the mean.

PAGE 97

97 Table 4 12. Water holding capacity percentages for boneless and skinless broiler chicken breast meat marinated with sodium metasilic ate and stored at 4C for 9 days : WHC with distilled water only Storage time Attribute Treatment 3 d 1 5 d 7 d 9 d SEM WHC water, % Control 35.76 a,xy 29.94 b,xy 62.50 a,x 17.74 c,y 12.76 1% SMS 33.25 a,yz 56.37 a,x 48.79 ab,xy 18.44 c,z 6.65 2% SMS 39.72 a,x 52.97 ab,x 31.09 b,x 25.28 bc,x 13.21 3% SMS 28.75 a,y 52.97 ab,x 57.88 ab,x 36.44 ab,y 2.84 4% SMS 58.39 a,x 36.85 ab,x 58.63 ab,x 42.35 a,x 10.32 SEM 12.45 8.96 11.43 5.56 ac M eans in same column with different superscripts differ significantly (P < 0.0 5); x z M eans in same row with different superscripts differ significantly (P < 0.05); 1 the data were available from day 3; n = 2 values per mean; WHC = Water holding capacity; NaCl = Sodium chloride; SMS = Sodium metasilicate; SEM = Standard error of the mean.

PAGE 98

98 Figure 4 9. Cooking yield percentages for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days

PAGE 99

99 Table 4 13. Tot al psychrotrophic counts for boneless and skinless broiler chicken br east meat marinated with sodium metasilicate and stored at 4C for 9 days Storage time Attribute Treatment 0 d 1 d 3 d 5 d 7 d 9 d SEM TPC, log cfu /g Control 3.91 a,z 4.21 a,yz 4.59 ab,y 6.48 a,x 7.93 a,w 8.74 b,v 0.19 1% SMS 3.95 a,z 3.81 ab,yz 4.97 a,y 6.19 ab,xy 7.95 a,wx 9.11 a,w 1.11 2% SMS 2.94 b,z 3.50 a,y 4.30 ab,x 5.53 bc,w 7.75 a,v 8.72 b,u 0.22 3% SMS 1 0.00 c,z 0.00 b,z 3.93 b,y 5.15 c,x 6.51 b,w 8.12 c,v 0.29 4% SMS 0.00 c,z 0.00 b,z 2.94 c,y 3.99 d,x 6.29 b,w 8.01 c,v 0.19 SEM 0.22 1.21 0.28 0.26 0.23 0.11 ad M eans in same column with different superscripts differ significantly (P < 0.05); uz M eans in same row with different superscripts differ significantly (P < 0.05); n = 4 values per mean; 1 M eans the plates counts fewer than 25 cfu the counts from plat es less than 2500/g. TPC = Total psychrotrophic counts SMS = Sodium metasilicate; SEM = Standard error of the mean.

PAGE 100

100 Table 4 14. Objective raw meat color L* values on boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days Storage time Attribute Treatment 0 d 1 d 3 d 5 d 7 d 9 d SEM L* Control 62.65 a,x 61.27 a,xy 60.07 a,xy 58.44 a,y 61.45 a,xy 57.83 a,y 1.99 1% SMS 62.23 ab,x 57.00 a,yz 63.04 a,x 55.39 b,z 60.43 a,xy 54.92 a,z 2.38 2% SMS 60.94 ab,x 57.65 a,x 49.48 a,x 55.19 b,x 58.68 a,x 58.02 a,x 7.25 3% SMS 58.98 b,x 56.64 a,x 58.69 a,x 56.56 ab,x 59.55 a,x 56.92 a,x 2.21 4% SMS 60.75 ab,x 60.12 a,x 60.65 a,x 56.57 ab,x 57.42 a,x 57.28 a,x 2.32 SEM 1.85 2.48 7.83 1.49 2.77 2.5 0 ac M eans in same column with different superscripts differ significantly ( P < 0.05); x z M eans in same row with different superscripts differ significantly (P < 0.05); n = 6 values per mean; SMS = Sodium metasilicate; SEM = Standard error of the mean.

PAGE 101

101 Table 4 15. Objective ra w meat color a* values for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days Storage time Attribute Treatment 0 d 1 d 3 d 5 d 7 d 9 d SEM a* Control 5.30 ab,yz 6.49 a,xyz 7.37 a,x 6.40 a,xyz 4.92 b,z 6.99 a,xy 0.99 1% SMS 6.18 a,x 6.77 a,x 6.23 a,x 6.85 a,x 6.71 ab,x 7.51 a,x 1.27 2% SMS 5.18 b,x 6.60 a,x 6.06 a,x 7.03 a,x 5.94 ab 5.27 a,x 1.2 0 3% SMS 5.70 ab,x 6.93 a,x 6.52 a,x 6.65 a,x 7.52 a,x 7.10 a,x 1.14 4% SMS 4.91 b,z 5.54 a,yz 5.40 a,yz 6.58 a,xy 7. 34 ab,x 7.87 a,x 0.80 SEM 0.51 1.18 1.02 0.99 1.27 1.39 ac M eans in same column with different superscripts differ significantly ( P < 0.05); x z M eans in same row with different superscripts differ significantly (P < 0.05); n = 6 values per mean; SMS = Sodium metasilicate; SEM = Standard error of the mean.

PAGE 102

102 Table 4 16. Objective raw meat color b* values for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days Storage time Attribute Tre atment 0 d 1 d 3 d 5 d 7 d 9 d SEM b* Control 15.79 ab,y 16.57 ab,y 16.68 a,y 18.68 a,xy 17.12 a,y 23.15 a,x 2.14 1% SMS 16.96 a,x 18.40 a,x 17.45 a,x 17.1 a,x 18.94 a,y 19.43 ab,x 1.79 2% SMS 13.42 bc,x 15.98 ab,x 14.81 a,x 16.21 a,x 17.51 a,x 13.92 b,x 2.80 3% SMS 14.54 abc,x 13.84 ab,x 15.78 a,x 16.12 a,x 17.66 a,x 18.92 ab,x 2.65 4% SMS 12.48 c,y 14.69 b,xy 14.47 a,xy 15.23 a,xy 16.20 a,xy 17.49 ab,x 2.09 SEM 1.69 2.22 1.93 1.79 2.78 3.13 ac M eans in same column with different superscripts differ significantly (P < 0 .05); x z M eans in same row with different superscripts differ significantly (P < 0.05); n = 6 values per mean; SMS = Sodium metasilicate; SEM = Standard error of the mean.

PAGE 103

103 Table 4 17. Objective cooked meat color L* values for boneless and skinless broil er chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days Storage time Attribute Treatment 0 d 1 d 3 d 5 d 7 d 9 d SEM L* Control 62.65 a,x 61.27 a,xy 60.07 a,xy 58.44 a,y 61.45 a,xy 57.83 a,y 1.99 1% SMS 62.23 ab,x 57.00 a,yz 63.04 a,x 55.39 b,z 60.43 a,xy 54.92 a,z 2.38 2% SMS 60.94 ab,x 57.65 a,x 49.48 a,x 55.19 b,x 58.68 a,x 58.02 a,x 7.25 3% SMS 58.98 b,x 56.64 a,x 58.69 a,x 56.56 ab,x 59.55 a,x 56.92 a,x 2.21 4% SMS 60.75 ab,x 60.12 a,x 60.65 a,x 56.57 ab,x 57.42 a,x 57.28 a,x 2.32 SEM 1.85 2.48 7.83 1.49 2.77 2.50 ac M eans in same column with different superscripts differ significantly (P < 0.05); x z M eans in same row with different superscripts differ significantly (P < 0.05); n = 6 values per mean; SMS = Sodium metasilicate; SEM = Standard error of the mean.

PAGE 104

104 Table 4 18. Objective cooked meat color a* values for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days Storage time Attribute Treatment 0 d 1 d 3 d 5 d 7 d 9 d SEM a* Control 5.30 ab,yz 6.49 a,xyz 7.37 a,x 6.40 a,xyz 4.92 b,z 6.99 a,xy 0.99 1% SMS 6.18 a,x 6.77 a,x 6.23 a,x 6.85 a,x 6.71 ab,x 7.51 a,x 1.27 2% SMS 5.18 b,x 6.60 a,x 6.06 a,x 7.03 a,x 5.94 ab,x 5.27 a,x 1.2 3% SMS 5.70 ab,x 6.93 a,x 6.52 a,x 6.65 a,x 7.52 a,x 7.10 a,x 1.14 4% SMS 4.91 b,z 5.54 a,yz 5.40 a,yz 6.58 a,xy 7.34 ab,x 7.87 a,x 0.8 SEM 0.51 1.18 1.02 0.99 1.27 1.39 ac M eans in same column with different superscripts differ significantly (P < 0.05); x z M eans in same row with different superscripts differ significantly (P < 0.05); n = 6 values per mean; SMS = Sodium metasilicate; SEM = Standard error of the mean.

PAGE 105

105 Table 4 19. Objective raw meat color b* values for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days Storage time Attribute Treatment 0 d 1 d 3 d 5 d 7 d 9 d SEM b* Control 15.79 ab,y 16.57 ab,y 16.68 a,y 18.68 a,xy 17.12 a,y 23.15 a,x 2.14 1% SMS 16.96 a,x 18.40 a,x 17.45 a,x 17.10 a,x 18.94 a,x 19.43 ab,x 1.79 2% SMS 13.42 bc,x 15.98 ab,x 14.81 a,x 16.21 a,x 17.51 a,x 13.92 b,x 2.8 3% SMS 14.54 abc,x 13.84 ab,x 15.78 a,x 16.12 a,x 17.66 a,x 18.92 ab,x 2.65 4% SMS 12.48 c,y 14.69 b,xy 14.47 a,xy 15.23 a,xy 16.20 a,xy 17.49 ab,x 2.09 SEM 1.69 2.22 1.93 1.79 2.78 3.13 ac M eans in same c olumn with different superscripts differ significantly (P < 0.05); x z M eans in same row with different superscripts differ significantly (P < 0.05); n = 6 values per mean; SMS = Sodium metasilicate; SEM = Standard error of the mean.

PAGE 106

106 Table 4 20. Warner B ratzler shear force for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days storage time Attribute Treatment 0 d 1 d 3 d 5 d 7 d 9 d SEM Warner Bratzler s hear force, Kg Control 1.65 a,x 1.18 c ,y 1.55 a,xy 1.83 ab,x 1.54 a,xy 1.40 a,xy 0.35 1% SMS 1.82 a,xy 1.80 a,xy 1.70 a,xy 2.03 a,x 1.58 a,xy 1.50 a,y 0.38 2% SMS 1.91 a,x 1.36 abc,y 1.51 a,xy 1.58 b,xy 1.55 a,xy 1.41 a,y 0.35 3% SMS 1.78 a,x 1.32 bc,y 1.52 a,xy 1.69 ab,xy 1.49 a,xy 1.62 a,xy 0.31 4% SMS 1. 53 a,xy 1.66 ab,xy 1.53 a,xy 1.88 ab,x 1.41 a,y 1.54 a,xy 0.29 SEM 0.37 0.36 0.40 0.34 0.30 0.25 ab M eans in same column with different superscripts differ significantly (P < 0.05); x y M eans in same row with different superscripts differ significantly (P < 0.05); n = 6 values per mean; SMS = Sodium metasilicate; SEM = Standard error of the mean.

PAGE 107

107 Table 4 21. Panelist rating for juiciness and chicken flavor intensity for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days Storage time Attribute Treatment 0 d 1 d 3 d 5 d 7 d 9 d SEM Juiciness Control 6.83 ab,x 6.43 a,xy 6.50 a,xy 5.29 a,y 6.33 a,xy 5.75 ab,xy 1.26 1% SMS 6.83 ab,x 6.86 a,x 6.33 a,xy 6.00 a,xy 6.56 a,x 4.88 b,y 1.32 2% SMS 5.50 bc,x 5. 71 a,x 7.00 a,x 6.14 a,x 6.44 a,x 6.25 a,x 1.29 3% SMS 8.00 a,x 6.43 a,y 6.00 a,y 5.43 a,y 5.89 a,y 6.38 a,y 1.21 4% SMS 5.17 c,x 6.29 a,x 6.00 a,x 6.14 a,x 6.33 a,x 5.50 ab,x 1.20 SEM 1.20 1.52 1.15 1.40 1.09 1.17 Chicken Flavor Control 6.50 b,x 6.43 a,x 6 .00 a,x 5.71 a,x 5.67 a,x 5.75 a,x 1.43 1% SMS 6.50 b,x 6.43 a,x 6.00 a,x 6.14 a,x 5.56 a,x 5.25 a,x 1.43 2% SMS 6.33 b,x 5.86 a,x 6.00 a,x 6.14 a,x 5.22 a,x 5.38 a,x 1.44 3% SMS 8.00 a,x 6.00 a,y 5.67 a,y 5.86 a,y 5.44 a,y 5.13 a.x 1.57 4% SMS 6.00 b,x 6.00 a,x 5.50 a,x 6 .00 a,x 5.56 a,x 5.00 a,x 1.63 SEM 1.03 0.94 0.96 1.59 1.60 2.16 ac M eans in same column with different superscripts differ significantly (P < 0.05); x y M eans in same row with different superscripts differ significantly (P < 0.05); n = 10 values per m ean; Sensory scale: Eight point sensory scale for juiciness, chicken flavor where 8 = extremely juicy/intense, 7 = very juicy/intense, 6 = moderately juicy/intense, 5 = slightly juicy/intense, 4 = slightly dry/bland, 3 = moderately dry/bland, 2 = very dry / bland, 1 = extremely dry/bland; SMS = Sodium metasilicate; SEM = Standard error of the mean.

PAGE 108

108 Table 4 22. Panelist rating for tenderness and off flavor for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored a t 4C for 9 days Storage time Attribute Treatment 0 d 1 d 3 d 5 d 7 d 9 d SEM Tenderness Control 7.17 ab,x 7.29 a,x 7.50 a,x 6.71 a,x 7.00 a,x 7.13 a,x 1.01 1% SMS 6.83 b,x 7.29 a,x 7.17 a,x 7.00 a,x 7.00 a,x 6.75 a,x 1.19 2% SMS 6.67 b,x 6.86 a,x 7.67 a,x 7.29 a,x 7.33 a,x 7.13 a,x 1.01 3% SMS 8.00 a,x 7.14 a,xy 7.67 a,xy 6.86 a,y 7.00 a,xy 7.38 a,xy 0.91 4% SMS 6.33 b,x 7.14 a,x 7.17 a,x 6.86 a,x 7.11 a,x 6.88 a,x 1.06 SEM 0.90 1.15 0.63 1.07 1.08 1.19 Off flavor Control 6.00 a,x 5.71 a,x 6.00 a,x 6.00 a,x 5.56 a,x 5.63 a,x 0.65 1% SMS 6.00 a,x 5.71 a,x 6.00 a,x 5.86 a,x 5.56 a,x 5.75 a,x 0.57 2% SMS 5.67 a,x 5.57 a,x 5.83 a,x 6.00 a,x 5.78 a,x 5.75 a,x 0.54 3% SMS 6.00 a,x 5.57 a,x 5.33 a,x 6.00 a,x 5.78 a,x 5.75 a,x 0.62 4% SMS 5.67 a,x 5.57 a,x 5.67 a,x 5.86 a,x 5.67 a,x 5.62 a,x 0.64 SEM 0.52 0.58 0.68 0.24 0.8 0.59 ab M eans in same column with different superscripts differ significantly (P < 0.05); x y M eans in same row with different superscripts differ significantly (P < 0.05); n = 10 values per mean; Sensory scale: Eight point sensory scale for tenderness where 8 = extremely tender, 7 = very tender, 6 = moderately tender, 5 = slightly tender, 4 = slightly tough, 3 = moderately tough, 2 = very tough, 1 = extremely tough. A six point scale for off flavor where 6 = none detected, 5 = threshold, barely detected, 4 = slight off flavor, 3 = moderate off flavor, 2 = strong off flavor, 1 = extreme off flavor; SMS = Sodium metasilicate; SEM = Standard error of the mean.

PAGE 109

109 Figure 4 10. Marination yield percentages for bonel ess and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days

PAGE 110

110 Table 4 23. Mean pH measurement s for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days Storage time Attribute Treatment 0 d 1 d 3 d 5 d 6 d 7 d 9 d SEM pH Control 6.29 b,z 6.57 c,wxy 6.29 d,z 6.42 c,yz 6.44 c,xyz 6.71 b,w 6.67 b,wx 0.15 1% SMS 6.72 b,x 6.65 c,x 6.60 c,x 6.66 bc,x 6.57 c,x 6.75 b,x 6.70 b,x 0.18 2% SMS 7.28 a,x 7.08 b,xy 6.99 b,xy 6.96 ab,xy 6.75 bc,y 6.79 b,y 7.03 a,xy 0.29 3% SMS 7.40 a,x 7.40 ab,x 7.21 b,xy 7.08 a,xy 6.98 ab,y 7.03 a,xy 7.00 a,y 0.24 4% SMS 7.61 a,xy 7.69 a,x 7.71 a,x 7.27 a,xyz 7.16 a,yz 7.22 a,xyz 6.99 a,z 0.31 SEM 0.37 0.88 0.16 0.25 0.25 0.14 0.18 ac M eans in same column with different superscripts differ significantly (P < 0.05); wz M eans in same row with different superscripts differ significantly (P < 0.05); n = 4 values per mean; SMS = Sodium metasilicate; SEM = Standard error of the mean.

PAGE 111

111 Table 4 24. Mean w ater holding capacity percentages for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days : WHC with sodium chloride and distilled water Storage time Attribute Treatment 0 d 1 d 3 d 5 d 6 d 7 d 9 d SEM WHC Nacl, % Control 144.98 137.17 135.66 146.55 147.17 144.67 146.94 12.30 1% SMS 143.38 142.49 147.06 147.75 148.85 148.26 147.26 6.56 2% SMS 149.06 148.25 146.47 146.58 145.11 148.52 146.57 3.66 3% SMS 148.28 148.07 148.13 144.05 143.1 4 147.05 149.37 6.54 4% SMS 147.42 148.24 143.50 144.81 145.78 148.32 147.91 4.64 SEM 6.85 9.27 13.08 4.63 6.08 2.83 3.27 WHC Water,% Control 28.04 a,xy 33.37 ab,xy 18.44 b,y 25.78 a,y 19.50 a,y 31.57 ab,xy 42.37 a,x 9.96 1% SMS 30.56 a,xy 24.84 b,xy 21.41 a,xy 26.97 a,xy 19.48 a,y 25.52 b,xy 32.29 a,x 7.51 2% SMS 34.95 a,x 28.97 ab,xy 28.63 ab,xy 31.14 a,x 21.32 a,y 27.54 b,x 29.20 a,xy 5.62 3% SMS 35.93 a,x 36.56 a,x 30.69 a,x 25.45 a,x 23.29 a,x 24.90 b,x 32.47 a,x 8.66 4% SMS 40.06 a,x 35.00 ab,xy 25.57 ab,y 33.52 a,xy 25.25 a,y 39.60 a,x 34.24 a,xy 8.27 SEM 10.83 6.80 6.89 8.03 4.50 6.13 11.36 ab M eans in same column with different superscripts differ significantly (P < 0.05); x y M eans in same row with different superscripts differ significantly (P < 0.05); n = 4 values per mean; WHC = Water holding capacity; NaCl = Sodium chloride SMS = Sodium metasilicate; SEM = Standard error of the mean.

PAGE 112

112 Table 4 25. Mean purge loss percentages for boneless and skinless broiler chicken breast meat marinated with sodi um metasilicate and stored at 4C for 9 days Storage time Attribute Treatment 0 d 1 d 3 d 5 d 6 d 7 d 9 d SEM Purge loss, % Control 6.70 a,x 6.64 a,x 6.29 a,x 7.63 a,x 6.39 a,x 7.09 a,x 10.45 ab,x 2.97 1% SMS 5.59 a,x 4.94 a,x 6.89 a,x 6.10 a,x 5.68 a,x 6.47 a,x 10.21 b,x 3.55 2% SMS 4.75 a,y 6.20 a,xy 6.75 a,xy 6.68 a,xy 5.64 a,y 6.57 a,xy 11.25 a,x 3.35 3% SMS 4.17 a,x 4.94 a,x 5.11 a,x 7.17 a,x 5.53 a,x 5.32 a,x 8.68 c,x 3.64 4% SMS 4.97 a,x 4.33 a,x 4.50 a,x 5.70 a,x 4.13 a,x 5.56 a,x 8.29 c,x 3.67 SEM 3.19 3.59 4.20 3.40 3.66 4.14 0.53 ac M eans in same column with different superscripts differ significantly (P < 0.05); x y M eans in same row with different superscripts differ significantly (P < 0.05); n = 4 values per mean; SMS = Sodium metasilicate; SEM = Standard error of the mean.

PAGE 113

113 Table 4 26. Mean cooking yield percentages for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 6 days Storage time Attribute Treatment 0 d 1 d 3 d 1 5 d 1 6 d SEM Cooking yield, % Control 80.35 bc,xy 80.72 a,x 74.81 b,z 75.32 b,yz 81.24 c,x 2.74 1% SMS 79.13 c,xy 80.77 a,xy 69.09 c,z 75.04 b,yz 85.01 abc,x 4.83 2% SMS 86.41 b,x 80.43 a,xy 78.83 ab,y 73.60 b,y 88.24 ab,x 3.90 3% SMS 93.03 a,x 85.25 a,yz 81.90 a,z 86.29 a,xy 85.93 a,xy 3.28 4% SMS 85.66 b,x 86.96 a,x 82.38 a,x 85.22 a,x 86.81 bc,x 3.13 SEM 3.92 4.64 2.76 3.94 1.81 ac M eans in same column with different superscripts differ significantly (P < 0.05); x z M eans in same row with different superscripts differ significantly (P < 0.0 5); n = 4 values per mean; 1 on trial II, only 3% and 4% treatments were not spoiled on 5 d and 6 d; SMS = Sodium metasilicate; SEM = Standard error of the mean.

PAGE 114

114 Table 4 27. Mean total psychrotrophic counts for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days Storage time Attribute Treatment 0 d 1 d 3 d 5 d 6 d 7 d 9 d SEM TPC, log cfu /g Control 4.27 a,z 4.20 a,z 6.54 a,y 8.56 a,x 8.97 a,wx 9.50 a,w 9.69 a,w 0.52 1% SMS 3.80 a,z 3.93 a,z 6.40 a,y 8.23 a,x 8.91 a,w 9.41 a,w 9.33 ab,w 0.46 2% SMS 0.68 b,z 2.89 a,y 5.76 ab,x 8.44 a,w 8.74 ab,w 9.44 a,w 9.38 ab,w 0.96 3% SMS 1 0.00 b,z 0.00 b,z 4.78 b,y 6.81 b,x 7.84 ab,x 9.16 a,w 9.07 bc,w 0.76 4% SMS 0.00 b,z 0.00 b,z 4.99 b,y 6.22 b,x 8.02 b,w 8.42 b,w 8.74 c,w 0.6 9 SEM 0.76 1.00 0.77 0.80 0.64 0.31 0.34 ac M eans in same column with different superscripts differ significantly (P < 0.05); wz M eans in same row with different superscripts differ significantly (P < 0.05); n = 4 values per mean; 1 means the plates counts fewer than 25 CFU, the counts from plates less than 2500/g; TPC = Total psychrotrophic counts; SMS = Sodium metasilicate; SEM = Standard error of the mean.

PAGE 115

115 Table 4 28. Mean objective raw meat color L* values for boneless and skinless broiler chic ken breast meat marinated with sodium metasilicate and s tored at 4C for 9 days Storage time Attribute Treatment 0 d 1 d 3 d 5 d 6 d 7 d 9 d SEM L* Control 62.83 a,w 60.00 a,wx 59.97 a,wx 57.08 a,xy 55.54 b,yz 52.91 c,z 55.80 ab,yz 2.11 1% SMS 61.57 ab,w 5 9.47 a,wx 57.81 ab,xy 57.46 a,xy 56.30 ab,yz 55.78 bc,yz 55.44 b,z 1.65 2% SMS 59.38 b,x 58.32 a,xy 56.61 b,xy 58.63 a,xy 57.35 ab,xy 58.11 ab,xy 55.33 ab,y 2.39 3% SMS 61.00 ab,x 59.15 a,x 58.90 ab,x 58.37 a,x 58.52 a,x 60.45 a,x 58.09 ab,x 2.16 4% SMS 60.10 ab,x 58.42 a,xy 56.70 b,y 57.59 a,xy 56.15 ab,y 58.69 ab,xy 58.82 a,xy 2.02 SEM 1.83 2.2 0 1.78 2.29 1.75 2.12 2.47 ac M eans in same column with different superscripts differ significantly (P < 0.05); x z M eans in same row with different superscripts differ significa ntly (P < 0.05); n = 16 values per mean; SMS = Sodium metasilicate; SEM = Standard error of the mean.

PAGE 116

116 Table 4 29. Mean objective raw meat color a* values for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days Storage time Attribute Treatment 0 d 1 d 3 d 5 d 6 d 7 d 9 d SEM a* Control 4.69 a,z 5.59 a,yz 5.82 a,yz 5.90 a,yz 6.42 a,yz 8.70 a,x 7.01 a,xy 1.22 1% SMS 5.38 a,x 5.79 a,x 6.88 a,x 5.14 a,x 5.70 a,x 5.64 b,x 5.82 ab,x 1.23 2% SMS 6.23 a,x 5. 63 a,x 6.29 a,x 5.31 a,x 5.56 a,x 5.09 b,x 5.47 ab,x 1.24 3% SMS 5.29 a,xy 4.98 a,xy 5.05 a,xy 5.89 a,x 4.79 a,xy 4.12 b,y 4.41 b,xy 0.97 4% SMS 5.52 a,x 4.96 a,xy 6.21 a,x 5.70 a,x 5.04 a,xy 4.73 b,xy 3.94 b,y 0.96 SEM 0.98 0.83 1.24 1.14 1.12 1.15 1.38 ab M eans i n same column with different superscripts differ significantly (P < 0.05); x y M eans in same row with different superscripts differ significantly (P < 0.05); n = 16 values per mean; SMS = Sodium metasilicate; SEM = Standard error of the mean.

PAGE 117

117 Table 4 30. Mean objective raw meat color b* values for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 9 days Storage time Attribute Treatment 0 d 1 d 3 d 5 d 6 d 7 d 9 d SEM b* Control 18.97 a,z 22.40 a,yz 24.62 a,y 25.36 a,y 26.74 a,y 33.35 a,x 27.22 a,y 3.19 1% SMS 19.95 a,z 20.71 ab,yz 24.16 a,xyz 22.95 ab,yz 24.42 ab,xyz 29.46 ab,x 25.96 a,xy 3.40 2% SMS 20.06 a,z 19.42 b,z 21.95 a,xyz 22.28 ab,xyz 21.12 bc,yz 26.31 ab,x 26.08 a,xy 3.19 3% SMS 19.16 a,xy 16.91 c,y 17.97 b,xy 21.06 bc,xy 18.43 cd,xy 22.74 b,x 22.07 a,x 2.93 4% SMS 17.11 a,xy 14.88 c,y 17.81 b,xy 17.90 c,xy 16.77 d.xy 20.62 b,x 21.39 a,x 3.12 SEM 2.54 1.47 2.61 2.48 2.36 5.54 3.54 ab M eans in same column with different superscripts differ significantly (P < 0.05); x z M eans in same row with different superscripts differ significantly (P < 0.05); n = 16 values per mean; SMS = Sodium metasilicate; SEM = Standard error of the mean.

PAGE 118

118 Table 4 31. Mean cooked meat color for boneless and skinless broiler chick en breast meat marinated with sodium metasilicate and stored at 4C for 6 days Storage time Attribute Treatment 0 d 1 d 3 d 5 d 6 d SEM L* Control 81.29 a,x 82.42 a,x 77.21 a,x 76.79 b,x 78.66 a,x 5.17 1% SMS 82.00 a,x 81.98 a,x 80.47 a,xy 78.09 ab,y 79.65 a,xy 1.70 2% SMS 79.33 ab,x 80.58 b,x 80.70 a,x 79.13 ab,x 78.90 a,x 1.68 3% SMS 79.58 ab,x 80.25 b,x 80.57 a,x 81.08 a,x 81.34 a,x 2.21 4% SMS 77.73 b,y 80.11 b,xy 79.84 a,xy 79.09 b,xy 80.80 a,x 1.49 SEM 2.18 0.92 4.70 1.34 1.84 a* Control 1.7 8 b,yz 2.25 a,yz 1.74 b,z 3.72 a,x 2.76 a,y 0.51 1% SMS 1.96 b,x 2.09 a,x 2.06 ab,x 2.66 a,x 3.00 a,x 0.55 2% SMS 2.55 ab,x 2.03 a,x 2.30 ab,x 2.84 a,x 2.69 a,x 0.44 3% SMS 2.89 a,x 2.10 a,y 2.31 ab,xy 1.76 a,y 1.83 a,y 0.44 4% SMS 3.00 a,x 2.13 a,x 2.59 a,x 2.16 a,x 2.30 a,x 0.53 SEM 0.58 0.46 0.42 0.45 0.55 b* Control 17.61 b,y 18.45 a,y 18.09 a,y 20.73 a,x 18.08 a,y 1.14 1% SMS 19.02 b,x 17.93 a,x 18.65 a,x 18.89 b,x 18.61 a,x 1.84 2% SMS 21.71 a,x 19.43 a,x y 19.13 a,xy 19.91 ab,xy 18.76 a,y 1.32 3% SMS 21.51 a,x 18 .28 a,yz 19.40 a,y 19.80 ab,xy 17.07 a,z 1.33 4% SMS 21.88 a,x 19.47 a,yz 20.06 a,y 20.70 a,xy 18.16 a,z 1.00 SEM 1.59 1.24 1.48 0.68 1.25 ac M eans in same column with different superscripts differ significantly (P < 0.05); x z M eans in same row with diff erent superscripts differ significantly (P < 0.05); 1On trial II, only 3% and 4% treatments were not spoiled on 5 d and 6 d; n = 24 values per mean; SMS = Sodium metasilicate; SEM = Standard error of the mean.

PAGE 119

119 Table 4 32. Mean Warner Bratzler shear force for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 6 days Storage time Attribute Treatment 0 d 1 d 3 d 1 5 d 1 6 d SEM Warner Bratzler shear force, Kg Control 2.08 a,y 2.03 b,y 1.95 a,y 1.82 a,y 2 .81 a,x 0.27 1% SMS 2.17 a,xy 2.59 a,xy 2.42 a,xy 1.96 a,y 2.86 a,x 0.37 2% SMS 2.21 a,xy 2.66 a,x 2.31 a,xy 1.85 a,y 2.36 a,xy 0.29 3% SMS 2.13 a,x 2.54 a,x 2.34 a,x 2.04 a,x 2.80 a,x 0.57 4% SMS 2.25 a,x 2.15 b,x 2.28 a,x 2.20 a,x 2.26 a,x 0.30 SEM 0.29 0.20 0.29 0 .40 0.73 ab Means in same column with different superscripts differ significantly (P < 0.05); x y M eans in same row with different superscripts differ significantly (P < 0.05); n = 4 values per mean; 1on trial II, only 3% and 4% treatments were not spoi led on 5 d and 6 d; SMS = Sodium metasilicate; SEM = Standard error of the mean.

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120 Table 4 33. Panelist rating for juiciness and chicken flavor intensity for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 6 days Storage time Attribute Treatment 0 d 1 d 3 d 1 5 d 1 6 d SEM Juiciness Control 4.60 b,y 5.38 a,xy 5.92 a,x 5.09 a,xy 5.50 a,xy 0.65 1% SMS 4.11 b,y 4.69 a,xy 6.03 a,x 5.34 a,xy 5.63 a,xy 0.80 2% SMS 4.51 b,y 5.02 a,xy 6.13 a,x 6.04 a,x 5.50 a,xy 0.67 3% SMS 5.99 a,x 5.98 a,x 6.40 a,x 4.95 a,x 5.60 a,x 1.05 4% SMS 5.69 a,x 5.08 a,x 5.92 a,x 6.36 a,x 6.50 a,x 0.99 SEM 0.65 0.96 0.76 1.13 0.90 Chicken Flavor Control 5.08 ab,x 4.23 a,x 4.90 a,x 5.34 a,x 5.00 a,x 0.98 1% SMS 3.90 b,y 4.88 a,xy 5.26 a,xy 5.79 a,x 5.13 a,xy 0.85 2% SMS 4.53 ab,x 4.58 a,x 5.35 a,x 4.59 a,x 4.75 a,x 0.88 3% SMS 6.04 a,x 5.88 a,x 5.97 a,x 5.21 a,x 4.68 a,x 1.33 4% SMS 5.20 ab,y 5.19 a,y 5.53 a,xy 6.63 a,x 6.29 a,xy 1.09 SEM 0.42 1.15 0.80 1.10 1.23 ab M eans in same column with different superscripts differ significantly (P < 0.05); x y means in same row with different superscripts differ significantly (P < 0.05); n = 20 values per mean; Sensory scale: Eight point sensory scale for juiciness, chicken flavor where 8 = extremely juicy/intense, 7 = very juicy/intense, 6 = moderately juicy/intense, 5 = slightly juicy/intense, 4 = slightly dry/bland, 3 = moderately dry/bland, 2 = very dry/bland, 1 = extremely dry/bland. 1 on trial II, only 3% and 4% treatments were not spoiled on 5 d and 6 d; SMS = Sodium metasilicate; SEM = Standard error of the mean.

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121 Table 4 34. Panelist rating for tenderness and off flavor for boneless and skinless broiler chicken breast meat marinated with sodium metasilicate and stored at 4C for 6 days Stor age time Attribute Treatment 0 d 1 d 3 d 1 5 d 1 6 d SEM Tenderness Control 5.61 a,x 5.48 b,x 6.46 a,x 7.54 a,x 7.13 a,x 1.40 1% SMS 7.84 a,x 5.81 ab,x 6.08 a,x 7.67 a,x 7.13 a,x 1.33 2% SMS 7.16 a,x 7.33 a,x 7.49 a,x 7.67 a,x 7.13 a,x 0.33 3% SMS 6.93 a,xy 7.19 ab,x 7.24 a,x 6.31 a,xy 5.71 a,y 0.78 4% SMS 6.38 a,x 6.15 ab,x 6.65 a,x 6.71 a,x 6.40 a,x 0.77 SEM 1.00 1.08 0.98 0.76 0.94 Off Flavor Control 5.29 a,y 5.79 a,x 5.94 a,x 5.25 b,y 6.00 a,x 0.29 1% SMS 5.75 a,x 5.86 a,x 5.69 a,x 5.88 a,x 5.75 ab,x 0.34 2% SMS 5.70 a,x 5.73 ab,x 5.81 a,x 5.59 ab,x 5.38 b,x 0.22 3% SMS 5.63 a,x 5.94 a,x 5.82 a,x 5.83 a,x 5.78 ab,x 0.29 4% SMS 5.81 a,x 5.52 b,x 5.55 a,x 5.82 a,x 5.81 ab,x 0.27 SEM 0.36 0.17 0.25 0.27 0.27 ab M eans in same column with different superscripts differ signi ficantly (P < 0.05); x y M eans in same row with different superscripts differ significantly (P < 0.05); n = 20 values per mean; Sensory scale: Eight point sensory scale for tenderness where 8 = extremely tender, 7 = very tender, 6 = moderately tender, 5 = slightly tender, 4 = slightly tough, 3 = moderately tough, 2 = very tough, 1 = extremely tough. A six point scale for off flavor where 6 = none detected, 5 = threshold, barely detected, 4 = slight off flavor, 3 = moderate off flavor, 2 = strong off flavor, 1 = extreme off flavor; 1 on trial II, only 3% and 4% treatments were not spoiled on 5 d and 6 d; SMS = Sodium metasilicate; SEM = Standard error of the mean.

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122 CHAPTER 5 SUMMARY AND CONCLUSI ON Results from this study suggested that the fillets treated wi th sodium metasilicate had higher marination yield, when compared to control treatment. The pH values of meat after marination with sodium metasilicate increased, and the values of pH were close to neutral point (pH = 7). The water holding capacity measure d with sodium chloride for fillets were similar among all treatments through 9 days storage. The water holding capacity measured with distilled water for fillets treated with 3% and 4% sodium metasilicate were slightly higher than control fillets. The purge loss percentages for all treatments were similar through 7 days storage. The fillets treat ed with 3% sodium metasilicate had higher cooking yield than control fillets. The fillets treated with 3% and 4% sodium metasilicate had one additional day of shelf life, when compared to control fillets. Fillets treated with 3% sodium metasilicate were darker during the first 3 days of storage, when compared to control fillets. But after day 3, the fillets treated with 3% sodium metasilicate were lighter than control fillets. The fillets treated with 3% and 4% sodium metasilicate were less yellow than control fillets, and had similar red color for all treatments. Based on the panelist responses, the fillets treated with 3% and 4% sodium metasilicate were juic i er than control fillets, and no significant differences were observed among all treatments for tenderness, chicken flavor intensity and off flavor characteristics. No significantly differences were observed for shear force values for all treatments. The results revealed that USDA approved levels were not effective to improve the meat quality and shelf life. The elevated levels of 3% and 4% sodium metasilicate could extend shelf life to two additional day s. T he disadvantages of sodium metasilicate

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123 treatments inclu ded discoloration (darken) of the fillets, and provided suitable pH values for microbial growth. More work should be conducted to investigate the utilization of sodium metasilicate in hurdle technology to improve the meat quality and shelf life. Hurdle tec hnology would include using sodium metasilicate in combination with other antimicrobials and at higher concentration levels (i.e .) for sodium metasilicate greater than approved level of 2% in marinade solutions.

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130 BIOGRAPHICAL SKETCH Huisuo Huang was born in Hebei province in China, in 1981. She received her Bachelor of Science degree in Food Science and Technology with honors from Hebei Normal University of Science & Technology, Qinhuangdao, China in 2005. S he worked in Hebei Food Additive Co., LTD. for one and half years after graduated. She started her master s degree in 2009 in Food S cience and Human Nutrition at the University of Florida. She conducted her master s research in the Department of An imal Sci ence since August 2009. Her current concentration was Food Safety and Food Microbiology. She earned her Mast er of Science degree in August 2010. Upon graduation, Huisuo plans to continue doing research in food industries or academy i nstitutes. Her ultimate goal is to accelerate the exchanges and cooperation between China and the United States about eco nomic and trade related with food.