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Evaluation of Ground Beef Quality from Commodity and Premium Quality Trimmings

Permanent Link: http://ufdc.ufl.edu/UFE0044701/00001

Material Information

Title: Evaluation of Ground Beef Quality from Commodity and Premium Quality Trimmings
Physical Description: 1 online resource (65 p.)
Language: english
Creator: Myers, Nicholas B
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2012

Subjects

Subjects / Keywords: beef -- color -- ground -- oxidation -- palatability -- premium -- quality -- sensory -- shelf-life -- trimmings
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: The objective of this research was to evaluate ground beef quality from commodity and premium quality trimmings.  Round subprimals were sourced from cows (COW), fed upper 2/3 Choice beef carcasses (TC), or fed beef carcasses with Slight or Small marbling (COM), and used as lean sources, while boneless plates from TC and COM carcasses were utilized as fat sources.  Lean and fat sources were mixed and ground to make 80 and 90% lean patties representing all 12 possible combinations.  Patties manufactured with COW as a leansource had greater subjective values lean color and were objectively a moreoptimal red at the beginning of retail display, however, these patties also had the greatest reduction in color stability by the conclusion of retail display.  Trained sensory panelists found few differences for lean source and no differences for fat source, while consumer panelists found no differences (P = 0.222) for overall acceptability or flavor between patties manufactured with different lean or fat sources.  At 4 d of retail display, TC lean (P £ 0.04) and fat (P £ 0.02) produced greater oxidation than anyother lean or fat source, respectively. 80% lean patties produced lower Lee-Kramer shear force values (P <0.001) than 90% lean patties.  Lean source had greater influence than fat source on retail color. Additionally, patties containing COW lean began retail display at a more ideal retail color, but declined more rapidly than TC or COM lean patties.  Lean and fat source had marginal impacton consumer or trained sensory palatability.
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 Nicholas B Myers.
Thesis: Thesis (M.S.)--University of Florida, 2012.
Local: Adviser: Carr, Charles Chad.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2012
System ID: UFE0044701:00001

Permanent Link: http://ufdc.ufl.edu/UFE0044701/00001

Material Information

Title: Evaluation of Ground Beef Quality from Commodity and Premium Quality Trimmings
Physical Description: 1 online resource (65 p.)
Language: english
Creator: Myers, Nicholas B
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2012

Subjects

Subjects / Keywords: beef -- color -- ground -- oxidation -- palatability -- premium -- quality -- sensory -- shelf-life -- trimmings
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: The objective of this research was to evaluate ground beef quality from commodity and premium quality trimmings.  Round subprimals were sourced from cows (COW), fed upper 2/3 Choice beef carcasses (TC), or fed beef carcasses with Slight or Small marbling (COM), and used as lean sources, while boneless plates from TC and COM carcasses were utilized as fat sources.  Lean and fat sources were mixed and ground to make 80 and 90% lean patties representing all 12 possible combinations.  Patties manufactured with COW as a leansource had greater subjective values lean color and were objectively a moreoptimal red at the beginning of retail display, however, these patties also had the greatest reduction in color stability by the conclusion of retail display.  Trained sensory panelists found few differences for lean source and no differences for fat source, while consumer panelists found no differences (P = 0.222) for overall acceptability or flavor between patties manufactured with different lean or fat sources.  At 4 d of retail display, TC lean (P £ 0.04) and fat (P £ 0.02) produced greater oxidation than anyother lean or fat source, respectively. 80% lean patties produced lower Lee-Kramer shear force values (P <0.001) than 90% lean patties.  Lean source had greater influence than fat source on retail color. Additionally, patties containing COW lean began retail display at a more ideal retail color, but declined more rapidly than TC or COM lean patties.  Lean and fat source had marginal impacton consumer or trained sensory palatability.
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 Nicholas B Myers.
Thesis: Thesis (M.S.)--University of Florida, 2012.
Local: Adviser: Carr, Charles Chad.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2012
System ID: UFE0044701:00001


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1 EVALUATION OF GROUND BEEF QUALITY FROM COMMODITY AND PREMIUM QUALITY TRIMMINGS BY NICHOLAS BARRETT MYERS 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 2012

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2 2012 Nicholas Barrett Myers

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3 To my parents and sisters for always supporting me and pushing me to be the absolute best

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4 ACKNOWLEDGMENTS Firstly, I would like to thank my committee chair Dr. Chad Carr for his tireless efforts and unwavering dedication and guidance throughout my graduate education at the University of Florida. The continuous help Chad offered me in and out of the office cannot be measured by any known scale. He hel ped make my transition from a place of comfort to the unknown personally and professionally has helped make my graduate experience incredible. It has been wonderful getting to know Chad and his wife Cathy, and I am proud to call them both my friends. Chad, from the bottom of my heart I thank you for everything you have done for me and I will continue to call on you for your priceless knowledge and friendship. Next, I would like to thank the members of my committee, Dr. Dwain Johnson and Dr. Charlie Sims. Their wisdom has helped me become a more well rounded meat scientist than I could have ever imagined. It was a privilege to be able to call on Dr. Johnson for his incredible wisdom of meat science, and I want to thank him for challenging me in the classroom and throughout the course of my research. The courses Dr. Sims teaches in sensory science are some of the absolute best in the country, and I thank him for lett ing me obtain some of that knowledge and apply it to my research. I want to also take this opportunity to thank all of the graduate and undergraduate students, as well as faculty at the University of Florida for your help with my research. Without their help special thank you goes out to Byron Davis, Tommy Estavez, Adam Spann, Mike Sexton and the rest of the UF meat processing crew for the tremendous help with maki ng patties and letting me take up space in the retail room. Another special thank you to Eric Dreyer and all of the staff at the Food Science and Human Nutrition sensory lab for helping me run my consumer sensory

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5 analysis. Their help was overwhelmingly a mazing and you made my job effortless. Thank you to Ryan Dijkhuis for helping me through my shear testing I want to thank Mr. Larry Eubanks for his help through every step in the process of my research. Additionally, his witty comments and fun personalit y make work much more enjoyable, and I will certainly call upon him in the future to make sure I stay grounded. I am also deeply indebted to Justin Crosswhite. Without his help in every step of my research, from making patties, to many late nights color scoring among countless other things, it would have never been possible. Justin Crosswhite and Mellissa Schook have been my two greatest friends during my time in Florida. Whether it was going to watch one of the many movies we saw, Mellissa cooking din ner for us, or just sitting on the couch watching jeopardy while Worm constantly shifted something I will cherish for the rest of my life, and I will keep in touch. Lastly, and most importantly, I must thank my family. I am truly blessed to have such a supporting and understand family. My parents have always encouraged me to chase my dreams, no matter which part of the country they may lead. They have alw ays stood behind the decisions I have made, let me make my own mistakes, and offered guidance and support when I needed them most. Their unwavering support, guidance and love have helped me achieve everything I have to this point, and I have no doubt any future success I achieve is directly attributed to them. I must also thank my sisters for their support and for pushing me to strive to be a better person. Thank you to the rest of family for your support, guidance and love throughout my life.

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6 TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................ ................................ ................................ ............... 4 LIST OF TABLES ................................ ................................ ................................ ........................... 8 LIST OF FIGURES ................................ ................................ ................................ ......................... 9 ABSTRACT ................................ ................................ ................................ ................................ ... 10 CHAPTER 1 INTRODUCTION ................................ ................................ ................................ .................. 12 2 REVIEW OF LITERATURE ................................ ................................ ................................ 14 Introductory Remarks ................................ ................................ ................................ ............. 14 Commercial Ground Beef Manufacturing ................................ ................................ .............. 15 Effect of Diet and Exerci se on Beef Quality ................................ ................................ ... 15 USDA Beef Quality Grading ................................ ................................ ........................... 18 Effect of USDA Marbling Score on Beef Quality ................................ ................................ .. 20 Palatability of Whole Muscle Steaks from the Loin or Rib ................................ ............ 20 Palatability of Whole Muscle Steaks from the Round or Chuck ................................ ..... 21 Shelf life ................................ ................................ ................................ .......................... 22 Palatability of Ground Beef ................................ ................................ ............................. 22 Effect of Physiological Age on Beef Quality ................................ ................................ ......... 23 Palatability of Whole Muscle Steaks ................................ ................................ ............... 23 Lean Color and Shelf life ................................ ................................ ................................ 23 P alatability of Ground Beef ................................ ................................ ............................. 25 Effect of Lean Percentage on Beef Quality ................................ ................................ ............ 26 Palatability and Objective Textural Analysis ................................ ................................ .. 26 Lean Color and Shelf life ................................ ................................ ................................ 27 3 EVALUATION OF GROUND BEEF QUALITY FROM COMMODITY AND PREMIUM QUALITY TRIMMINGS ................................ ................................ ................... 28 Materials and Methods ................................ ................................ ................................ ........... 28 Raw Materials ................................ ................................ ................................ .................. 28 Patty Manufacturing ................................ ................................ ................................ ........ 29 Fat Analysis ................................ ................................ ................................ ..................... 30 Retail Color Evaluation ................................ ................................ ................................ ... 31 Lipid Oxidation ................................ ................................ ................................ ............... 31 Cooking ................................ ................................ ................................ ........................... 32 Trained Sensory Evaluation ................................ ................................ ............................ 32 Consumer Sensory Evaluation ................................ ................................ ........................ 33 Lee Kramer Shear Force ................................ ................................ ................................ 3 4

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7 Statistics ................................ ................................ ................................ ........................... 34 Results and Discussion ................................ ................................ ................................ ........... 35 Carcass Data ................................ ................................ ................................ .................... 35 Raw Instrumental Color ................................ ................................ ................................ .. 35 Subjective Color ................................ ................................ ................................ .............. 38 Thiobarbituric Acid Reactive Substances (TBARS) ................................ ....................... 39 Consumer Sensory ................................ ................................ ................................ ........... 40 Traine d Sensory ................................ ................................ ................................ ............... 41 Lee Kramer Shear Force ................................ ................................ ................................ 41 Implications ................................ ................................ ................................ ............................ 42 LIST OF R EFERENCES ................................ ................................ ................................ ............... 59 BIOGRAPHICAL SKETCH ................................ ................................ ................................ ......... 65

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8 LIST OF TABLES Table P age 3 1 Schematic of lean source, fat source, and lean percentage formulation for manufacturing ground beef patties ................................ ................................ ..................... 44 3 2 Characteristics of beef carcasses used as lean source and fat source for manufac turing beef patties ................................ ................................ ................................ 45 3 3 Effect of fat source and lean percentage on objective color of beef patties. ..................... 46 3 4 Eff ect of lean source, fat source and lean percentage on consumer sensory traits of beef patties. ................................ ................................ ................................ ........................ 47 3 5 Effect of lean source, fat source and lean percentage on trained sensory traits of beef patties. ................................ ................................ ................................ ................................ 48

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9 LIST OF FIGURES Figure page 1 1 The relationship between marbling, maturity, and USDA quality grade. ......................... 13 3 1 Interactive effect of lean source a and day of retail display on lightness (L*) values (P = 0.002), redness (a*) values (P < 0.001), yellowness (b*) values (P = 0.049), hue angle values (a larger nu mber indicating a shift from red to yellow; (P < 0.001), and chroma values (a larger number indicates a more vivid color; P < 0.001) of beef patties. ................................ ................................ ................................ ................................ 49 3 2 Interactive effect of fat source a and day of retail display on hue angle values (a larger number indicating a shift from red to yellow; P = 0.026) of beef patties. ......................... 51 3 3 Interactive effect of fat source a and values (a larger number indicates a greater change in total color from day 0, P = 0.007) of beef patties. Values within day of retail display lacking common letters ................................ ................................ ................................ ............... 52 3 4 Interactive effect of lean source a lean percentage and day of retail display on subjective lean color b values (P = 0.005) and subjective percent discoloration c values (P < 0.001) of beef patties. ................................ ................................ ................................ 53 3 5 Interactive effect of fat source a lean percentage and day of retail display on subjective lean color b values (P = 0.002) and percent discoloration c values (P = 0.413) of beef pa tties. ................................ ................................ ................................ ......... 54 3 6 Interactive effect of lean source and day of retail display on thiobarbituric acid reactive substances (TBARS) expressed as mg of malondialdehyde per kg of ground beef ( P = 0.007). Va lues within day of retail display lacking common letters differ (P ................................ ................................ ................................ ............................. 55 3 7 Interactive effect of fat source a and day of retail display on thiobarbituric acid reactive substan ces (TBARS) expressed as mg of malondialdehyde per kg of ground beef (P = 0.002). Values within day of retail display lacking common letters differ (P ................................ ................................ ................................ ............................. 56 3 8 Interactive eff ect of lean source a and fat source b on the consumer perception of texture c (P = 0.027) of beef patties. Bars lacking a common letter differ (P = 0.002). .... 57 3 9 Interactive effect of lean source a fat source b and lean percentage on Lee Kramer shear force values (P = 0.003) of beef patties. Bars lacking a common letter within lean percentage differ (P 0.031). ................................ ................................ ..................... 58

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10 Abstract of Thesis Presented to the Gr aduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science EVALUATION OF GROUND BEEF QUALITY FROM COMMODITY AND PREMIUM QUALITY TRIMMINGS By Nicholas Barrett Myers August 201 2 Chair: Chad Carr Major: Animal Sciences The objective of this research was to evaluate ground beef quality from commodity and premium quality trimmings. Round subprimals were sourced from cows (COW), fed upper 2/3 Choice beef carcasses (TC), or fed be ef carcasses with Slight or Small marbling (COM), and used as lean sources, while boneless plates from TC and COM carcasses were utilized as fat sources. Lean and fat sources were mixed and ground to make 80 and 90% lean patties representing all 12 possib le combinations. Patties manufactured with COW as a lean source had greater subjective values lean color and were objectively a more optimal red at the beginning of retail display, however, these patties also had the greatest reduction in color stability by the conclusion of retail display. Trained sensory panelists found few differences for lean source and no differences for fat source, while consumer panelists found no differences ( P overall acceptability or flavor between patties manufactu red with different lean or fat sources. At 4 d of retail display, TC lean (P 0.04) and fat (P 0.02) produced greater oxidation than any other lean or fat source, respectively. 80% lean patties produced lower Lee Kramer shear force values (P < 0.001) than 90% lean patties. Lean source had greater influence than fat source on retail color. Additionally, patties containing COW lean began retail display at a more ideal retail

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11 color, but declined more rapidly than TC or COM lean patties. Lean and fat sou rce had marginal impact on consumer or trained sensory palatability.

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12 CHAPTER 1 INTRODUCTION Over 42% of per capita U.S. beef consumption has been as ground product over the past thirty years, making it clearly the most consumed beef product in the Unit ed States (NCBA, 2006). The recent economic recession has lead to an additional shift in demand from steaks and roasts toward ground beef, partially driven by the lower cost of ground products and the ability of ground beef to produce low cost meals. Cur rently, many retail and food service establishments are marketing ground beef from premium quality trimmings such as upper 2/3 Choice raw materials for added value; however, no known recent work has documented the differences between ground beef quality ma nufactured with premium or commodity trimmings. Therefore, the objective of this research was to evaluate the differences between commodity and premium quality trimmings on subjective and objective color analysis, consumer and trained sensory panels, oxid ation analysis (TBARS), and Lee Kramer shear force.

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13 Figure 1 1. The relationship between marbling, maturity, and USDA quality grade.

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14 CHAPTER 2 REVIEW OF LITERATURE Introductory Remarks Over 42% of per capita US beef consumption has been as ground product over the past thirty years, making it the most consumed beef product in the US (NCBA, 2006). Additionally, the strong demand for these products as compared to steaks and is driven by their lower cost, recipe versatility, and ease of preparation (D avis and Lin, 2005). The three most common forms of ground beef consumed are ground beef, hamburger, and beef patties. The Code of Federal Regulations (C.F.R.) defines ground beef as: Chopped fresh and/or frozen beef with or without seasoning and without the addition of beef fat as such, shall not contain more than 30 percent fat, and shall not contain added water, phosphates, binders or extenders (2008). Whereas, the C.F.R. defines hamburger as: Chopped fresh and/or frozen beef with or without the additio n of beef fat as such and/or seasoning, shall not contain more than 30 percent fat, and shall not contain added water, phosphates, binders or extenders (2008). Finally, beef patties are defined by the C.F.R. as: Chopped fresh and/or frozen beef with or wi thout the addition of beef fat as such and/or seasonings. Binders or extenders, Mechanically Separated (Species) used in accordance with §319.6, and/or partially defatted beef fatty tissue may be used without added water or with added water only in amount s such that the product characteristics are essentially that of the meat patty (2008). Many retail and food service establishments are currently marketing ground beef from premium quality trimmings such as upper 2/3 Choice (Modest or Moderate marbling degr ees in A maturity) to add value to ground beef products (USDA 1997). However, little recent, objective data exists comparing ground beef products made from premium quality raw materials with those from USDA Select, low Choice and non fed raw materials.

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15 C ommercial Ground Beef Manufacturing Comminuted muscle foods can be manufactured from any raw material, with particle size being the only difference between the original and end products. Particle size is first reduced by coarse grinding (1.2 0.6 cm) th e fat and lean sources separately to determine their lean percentages (Berry, 1980). Ground beef manufactured commercially for wholesale redistribution, is generally made by combining a very lean source of beef ( 10% fat) with a relatively high fat sourc e of beef ( 30% fat) to produce a final product with 20% fat (Berry, Marshall and Koch, 1981). The very lean beef used in ground beef production is attained from the carcasses of 1) U.S. and imported non fed market beef cows, 2) imported non fed steer s and heifers and/or 3) leaner trimmings from U.S grain fed (USDA, 2002) steers and heifers (Schaefer, Riemann and Rempe, 1999). The high fat beef used in ground beef production primarily comes from U.S. grain fed steer and heifer carcasses and is attaine d from subcutaneous fat trimmed from whole muscle subprimals or high fat subprimals such as plates and navels (Schaefer, Riemann and Rempe, 1999). Next, inclusion levels of both fat source and lean source are calculated, dependent on the final lean percen tage targeted. After determining lean and fat source levels of inclusion, the final products are made by mixing the lean and fat sources, prior to a final grind (0.5 0.3 cm; Cross, Berry, and Wells, 1980). Effect of Diet and Exercise on Beef Quality Ir relevant of age, beef cows are primarily fed forage and cows may walk 3 km or more daily, dependent upon their production system (DelCurto, Cochran, Nagaraja, Corah,.Beharka, and Vanzant, 1990), compared to market steers and heifers which are fed a diet co ntaining a high

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16 percentage of concentrate and generally receive less exercise (Dunne, Monahan, and Maloney, 2011). Diet and exercise both affect beef quality. The increased caloric intake from feeding cattle grain results in increased marbling scores wh en compared to feeding forage for the same length of time (Reagan, Carpenter, Bauer, and Lowrey, 1977; Hedrick, Paterson, Matches, Thomas, Morrow, Stringer, and Lipsey, 1983; Crouse, Cross, and Seideman., 1984). This increase in intramuscular fat helps to improve lean texture and firmness of grain grain, which is deposited within the fat of forage fed beef, resulting in more yellow colored fat (Yang, Brewster, Lanari and Tume, 2002). Di et affects the fatty acid profile of the fat deposited. The subcutaneous and external fat of beef from cattle fed pasture based diets have been found to have greater concentrations of n 3 polyunsaturated fatty acids (PUFA) when compared to cattle fed grai n (Yang, Brewster, Lanari and Tume, 2002; Realini, Duckett, Brito, Dalla Rizza, and De Mattos, 2004; Baublits, Brown, Pohlman, Rule, Johnson, Onks, Murrieta, Richards, Loveday, Sandelin, and Pugh, 2006; Leheska, Thompson, Howe, Hentges, Boyce, Brooks, Shri ver, Hoover, and Miller, 2008). As the percentage of n 3 PUFAs within beef products increases, so does their susceptibility to lipid oxidation (Leheska, Thompson, Howe, Hentges, Boyce, Brooks, Shriver, Hoover, and Miller, 2008). The ultimate pH of muscl e from forage fed cattle tends to be higher than that of grain fed 1997). The increase in ultimate pH is either due to lower glycogen reserves in the muscle and/or r educed fat coverage leading to faster cooling rates and slower postmortem pH decline (Faucitano, Chouinard, Fortin, Mandell, Lafreniere, Girard, and Bertiaume, 2008). Either hypothesis can be affected by diet and/or amount of antemortem energy expenditure Several

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17 authors reported pH and ultimately lean color did not differ when cattle fed forage or grain based diets were harvested at the same external backfat measurement, suggesting the validity of the cooling rate hypothesis (Mandell, Buchanan Smith, an d Campbell, 1998; Faucitano, Chouinard, Fortin, Mandell, Lafreniere, Girard, and Bertiaume, 2008). The relationship of external fatness with ultimate pH was supported within a U.S. population of grain fed steer and heifer carcasses with carcasses having l ess than 0.47 cm fat thickness at the 12 th /13 th rib producing greater 24 h pH values than carcasses with 0.67 fat thickness or more (Page, Wulf, and Schwotzer, 2001). Vestergaard, Oksberg, and Henckel (2000) suggested that forage based diets promote oxid ative muscle metabolism rather than anaerobic metabolism, and leads to reduced glycogen storage ability and, ultimately, less postmortem pH decline; however, dietary treatments differed for external fat thickness. Loin chops from pigs reared outdoors were more red and LM and semimembranosus muscles had greater percentage of more oxidative, type IIA fibers and a lower percentage of more glycolytic, IIB/X fibers than muscles from pigs reared indoors (Gentry, McGlone, Miller, and Blanton, 2004). Exercise cau ses accumulation of reactive oxygen species and may increase postmortem lipid oxidation resulting in accelerated meat discoloration (Dunne, pH. Generally, an incre ase in pH will increase water holding capacity and lean darkness due to increased light absorbency (Hedrick, Boillot, Brady, and Naumann, 1959). Moreover, the increased pH level holds myoglobin, the primary protein responsible for muscle color, in the fer rous state, which also causes a darker lean color (Lawrie, 1958). Furthermore, multiple authors have reported beef from forage fed cattle to be darker than beef from grain fed cattle

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18 (Bidner, Schupp, Mohamad, Rumore, Montgomery, Bagley and McMillin, 1986; Bennett, Hammond, Williams, Kunkle, Johnson, Preston and Miller, 1995; Baublits et al., 2004). USDA Beef Qua l ity Grading The purpose of USDA grading is to facilitate the marketing of beef on a sight unseen basis by developing a universal language and sep arating a homogenous population into heterogeneous groups (Tatum, 2007). Specifically, USDA quality grades are used in an attempt to predict the palatability of lean generated from beef carcasses. Eight quality grades designated to steer, heifer and cow carcasses, in descending order of quality: USDA Prime, Choice, Select, Standard, Commercial, Utility, Cutter and Canner; however, cows are not eligible for the USDA Prime grade (USDA, 1997). Beef quality grading is primarily based on two parameters: phys iological maturity and intramuscular fat, also known as marbling within the longissimus muscle (LM) at the 12/13 th rib interface. As vertebrates age, cartilage ossifies and turns into bone, while lean color becomes progressively coarser textured and darke r red. Therefore, physiological maturity of beef carcasses are assessed by 1) evaluating the maturity of the skeleton by determining the percentage of cartilage along the vertebral column which has ossified, as well as considering secondary indicators of maturity, such as rib shape and color; 2) evaluating LM color, texture and firmness at the 12/13 th rib interface. After evaluating skeletal maturity, and lean maturity, texture and firmness, skeletal and lean maturity are balanced and carcasses are assign ed a maturity group (A, B, C, D or E) based on the estimation of their approximate age. When skeletal and lean maturity indicators are different, slightly more emphasis is placed on skeletal maturity (USDA, 1997). The estimated chronological age associat ed in the maturity classifications of A E are: A = 9 30 months, B = 30 42 months, C = 42 72 months, D = 72 96 months, and E 96 months. Carcasses displaying A or B physiological maturity are eligible for

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19 the USDA Prime, Choice, Select and Standard grades while those of C, D and E physiological maturity are eligible for USDA Commercial, Utility, Cutter and Canner grades. Marbling is the amount of intramuscular fat within the LM at the 12 th /13 th rib interface, and is categorized by degrees, dependant upon the amount and distribution of intramuscular fat. The degrees of marbling in descending order of quality are: Abundant (A), Moderately Abundant (MA), Slightly Abundant (SA), Moderate (MD), Modest (MT), Small (SM), Slight (SL), Traces (TR) and Practically Devoid (PD). Figure 1 illustrates the relationship between marbling, maturity, and USDA quality grade. The Meat Grading and Certification Branch of the Livestock and Seed Program of the USDA AMS provides certification of beef carcasses for a number of m arketing programs making claims concerning cattle phenotype, such as breed type and hump height, and carcass characteristics, or only carcass characteristics. These characteristics go beyond the requirements for official USDA grades, and are often the bas is for approval of meat product labels making a variety of marketing claims for added value (USDA AMS, 2002). The originator of the certified program designates quality specifications for their program, and carcasses must be identified with an official US DA quality grade. Programs that specify a range of quality greater than two quality grades must label the product as the actual grade or specify the lowest possible grade and quality, the company name must precede the term on the label. For claims of cattle breed, animals must meet the phenotypic and/or genetic specifications set forth by the appropriate U.S. breed association (USDA AMS, 2002). Currently, the most well reco gnized USDA certified branded beef program is Certified Angus Beef (CAB), which has 10 live or carcass parameters that must be met to achieve the

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20 certification standards set by CAB and assessed by USDA Agriculture Marketing Service. All CAB carcasses must receive the phenotypic or genetic specification for characteristics of cattle eligible for approved beef programs claiming Angus influence known as GLA. The most discriminating variable is that the beef carcasses must display Modest 00 marbling or higher within the LM at the 12 th rib interface (USDA AMS, 2004). Effect of USDA Marbling Score on Beef Quality Palatability of Whole Muscle Steaks from the Loin or Rib It is well established that over a wide range of marbling scores within the LM, increased perc ent intramuscular fat associates with improved cooked palatability (Warriss, 2000). Classic work reported carcasses with a Moderate or Modest degree of marbling produced LM steaks with either a greater sensory panel ratings or lower Warner Bratzler shear force values, an objective measurement of cooked meat tenderness, than 37.9% and 37.1% of carcasses with lower marbling scores, respectively (Smith, Carpenter, Cross, Murphey, Abraham, Savell, Davis, Berry, and Parish, 1984). Moreover, the percentage of L M steaks with a composite sensory panel rating of 6.00 (6 = moderately desirable in flavor, moderately juicy, small amount of connective tissue, moderately tender and moderately desirable in overall palatability) and a shear force value of 3.63 kg was 59% and 50% for Moderate and Modest degrees of marbling, respectively. These authors reported marbling score to explain 24 to 34% of the variation in flavor, tenderness and overall palatability of A maturity LM steaks. In more recent work from carcasses selected using vision grading instrumentation, Emerson, Tatum, Woerner, Belk and Smith (2010) produced similar findings, that as degree of marbling increases, so too does sensory experience (MA = SA > MD = MT > SM > SL > TR). Furthermore, nearly all (98 t o 99%) of LM steaks with MA and SA marbling, and most (80 to

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21 90%) of the steaks with MD and MT marbling produced a positive overall sensory experience (panel rating 7.5) compared with steaks with SM, SL or TR marbling at 62, 29, and 15%, respectively. A clear designation of sensory quality experience between MD and MT degrees of Claborn (1996) reported that consumers found CAB LM steaks to be significantly more tender, jui cy, and flavorful than steaks from the USDA Select and low Choice grades. Additionally, trained panelists found CAB steaks greater in initial and sustained juiciness, tenderness, beef flavor intensity, overall beef flavor, and overall mouth feel. Further more, LM steaks from CAB carcasses exhibited lower Warner Braztler Shear Force values than USDA low Choice or Select steaks. Palatability of Whole Muscle Steaks from the Round or Chuck It is well documented that beef muscles of locomotion are generally le ss palatable and tougher than muscles of support. Muscles within the primals of the rib and loin are primarily muscles of support, while muscles within the primals of the round and chuck are muscles of locomotion (Rhee, Wheeler, Shackelford, and Koohmarai e, 2004). USDA marbling score is less consequential to the palatability of whole muscle steaks and roasts generated from the round and chuck than those from the rib and loin (Smith, Carpenter, Cross, Murphey, Abraham, and Savell, 1984; Von Seggern, Calkin s, Johnson, Brickler, and Gwartney, 2005). Nonetheless, USDA marbling score does have some influence in the palatability of whole muscle steaks and roasts from the round and chuck. Nelson, Dolezal, Ray, and Morgan (2004) investigated a variety of subprim als from the chuck and round in order to further quantify differences between CAB, and USDA low Choice and Select carcasses. When all subprimals were pooled, CAB steaks produced the lowest

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22 percentage of steaks with WBS values of greater than 4.6 kg, and t he highest percentage of steaks with WBS values less than 3.9 kg (Nelson, Dolezal, Ray, and Morgan, 2004). Additionally, trained sensory panelists found CAB and USDA low Choice steaks juicier, to produce greater beef fat flavor and to possess a greater fl avor intensity rating than USDA Select steaks (Nelson, Dolezal, Ray, and Morgan, 2004). No differences were found between overall tenderness, connective tissue amount, or off flavors between CAB, USDA low Choice and Select steaks when averaged across all six round and chuck subprimals (Nelson, Dolezal, Ray, and Morgan, 2004). Shelf life In an attempt to quantify the role of intramuscular fat in the shelf life of grain fed beef, LM steaks from USDA Prime, Choice, and Good, now called Select (USDA, 1997), f rom young steer and heifer carcasses were evaluated for 6 d of retail display (Correale, Savell, Griffin, Acuff and Vanderzant, 1986). Panelists found no initial differences in lean color among the three quality grades; however, USDA Prime steaks had less surface discoloration than USDA Good steaks, with USDA Choice being intermediate, by d 3 of retail display. At the conclusion of retail display, USDA Prime steaks had both brighter cherry red colored lean than USDA Good steaks, as well as less surface di scoloration, with USDA Choice being the intermediate. Conversely, Kennick, Turner, Buck, McGill, and Hartmann (1971) and Behrends, Mikel, Armstrong, and Newman (2003) reported color desirability was higher for low Choice steaks during retail display than those from high Choice, Select, or Prime grades. Palatability of Ground Beef In order to quantify sensory differences in the palatability of ground beef patties from different quality grades, Cross, Green, Stanfield, and Franks (1976) selected five carcas ses from the middle third of three USDA grades of youthful carcasses (USDA Prime, Choice and Good)

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23 and formulated ground beef patties to the same percent lean. A trained sensory panel found that patties formulated from USDA Prime and Choice carcasses were more tender than patties from USDA Good grade beef carcasses. Moreover, patties manufactured from USDA Prime carcasses had greater flavor and overall acceptability ratings than patties manufactured from USDA Good carcasses, while patties made from USDA C hoice carcasses were intermediate. Effect of Physiological Age on Beef Quality Palatability of Whole Muscle Steaks Breidenstein, Cooper, Cassens, Evans and Bray (1968) reported LM steaks from E maturity carcasses were higher in WBS values, as well as l ower in sensory panel ratings for tenderness and overall acceptability when compared to the same muscle fabricated from A and B maturity carcasses. Juiciness and flavor scores were not different among maturity groups. Likewise, rib steaks fabricated from A maturity carcasses received higher ratings for flavor, tenderness and overall palatability, as well as lower WBS values, when compared to rib steaks from C, D and E maturities, respectively (Smith, Berry, Savell and Cross, 1988). Moreover, rib steaks f abricated from E maturity carcasses received lower tenderness and overall palatability ratings, as well as higher WBS values compared to C and D maturity carcasses. Little difference was found in juiciness ratings between maturity classifications. Lean Color and Shelf life As vertebrates physiologically age, the concentration of myoglobin within muscle increases; thus, older animals tend to have darker colored lean (Tuma, Henrickson, Odell, and Stephens, 1963; Powell, 1991; Hedrick, Aberle, Forrest, Jud ge, and Merkel, 1994). As described earlier, lean color is an indicator of physiological maturity for USDA beef quality grades (USDA, 1997).

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24 The oxidation of oxymyoglobin to metmyoglobin and lipid peroxidation is the primary causes of fresh meat discolor ation and ultimately product devaluation (Smith, Belk, Sofos, Tatum and Williams. 2000). The o xidation of meat ultimately results in adverse changes not only to color, but flavor, texture and eventually nutritive value (Gray, 1996). Xiong, Mullins, Stika Chen, Blacnhard, and Moody (2007) assessed the influence of cow age on the chemical and biochemical changes during the postmortem storage of beef. They categorized cows into three age groups: 2 4 years old, 6 8 years old, and 10 12 years old. Oxidation was measured via the thiobarbituric acid reactive substances (TBARS) method for 7 d, and reported that the 10 12 year old age group was the most susceptible to lipid oxidation, while the 2 4 year old age group was the least susceptible to lipid oxidation, and the 6 8 year old age group was the intermediate; however, myoglobin oxidation was minimally affected by animal age. Multiple reports have documented beef from cows to have greater pH values than those from grain fed steers and heifers (Graafhuis and Devine, 1994; Patten, Hodgen, Stelzleni, Calkins, Johnson and Gwartney, 2008; Raines, Hunt and Unruh, 2009). Nonetheless, the differences between diet, exercise, and postmortem metabolic rate of muscle as influenced by antemortem stress and/or amount of external fat, cannot be clearly deciphered. Physiological age is not known to impact postmortem pH, holding everything else constant. Shemeis, Liboriussen and Bech Anderson (1994) evaluated meat quality traits of Danish Fresian cull cows based on age an d body condition score. The cattle were classified into 3 age groups: very young (< 3 years old), young (3 5 years old), and mature (> 5 years old). Overall carcass lean color darkened and fat became more yellow with age; however, only minor color changes due to age were observed within the LM. Patten, Hodgen, Stelzleni, Calkins, Johnson and Gwartney (2008) evaluated the color properties of nine different muscles from cow carcasses

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25 and USDA Select carcasses. They found six of the nine muscle evaluated (LM gluteus medius ,, triceps brachii psoas major rectus femoris and tensor facia latie) were darker (lower Hunter L*) from cow carcasses than the same muscles from A maturity Select grade beef steers. Little difference in muscle redness (Hunter a* values) was observed due to animal age. Raines, Hunt and Unruh (2009) evaluated patties made from two lean sources (beef cow lean versus dairy cow lean), two fat sources (young beef trim versus cow beef trim), and two lean percentages (80% lean and 90% lean) an d their impact on color stability. Patties made with beef cow lean were brighter (greater L* values) than patties made from dairy cow lean at the beginning of retail display, regardless of fat source; however, by the conclusion of the 4 d visual evaluatio n, patties made with dairy cow lean using beef cow trim as a fat source, showed superior visual color. Patties containing only beef cattle lean discolored more rapidly, developing a tannish red color by d 2 of retail display, while patties containing dair y cow lean, regardless of fat source, were the only treatments considered salable at on d 4 of retail display. For influence of fat source, patties made with the young beef trim fat were brighter (greater higher L* values) than patties using beef cow trim as the fat source. Palatability of Ground Beef As discussed previously, USDA Utility and Cutter are carcass grades applied to mature cattle, while USDA Prime, Choice, Good and Standard are associated with carcasses from youthful cattle. Cross, Green, S tanfield, and Franks (1976) found ground beef patties manufactured from USDA Cutter carcasses to be tougher than patties formulated from youthful carcasses. Furthermore, trained sensory panelists found that patties formulated from USDA Prime and Choice ca rcasses had less connective tissue and produced greater overall acceptability ratings compared to patties manufactured from USDA Utility and Cutter carcasses. Similarly, Berry and Abraham (1996) reported beef patties formulated from young beef carcasses ( < 24

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26 months) produced higher (more tender) sensory ratings for initial and final tenderness, as well as containing less connective tissue than beef patties formulated from mature beef carcasses (> 24 months). No significant differences were found in WBS v alues for peak load or peak energy between beef patties formulated from young beef or cow beef. Additionally, panelists found no differences for juiciness or flavor ratings. Effect of Lean Percentage on Beef Quality Palatability and Objective Textural Analysis Multiple researchers have reported using the same raw material sources to formulate ground beef patties from 14 to 28% percent fat (Cross, Berry, and Wells, 1980; Berry and Leddy, 1984). Trained panelists perceived cooked patties as tougher and as having more connective tissue as the fat percentage decreased. These findings were confirmed objectively, cooked patties with lower fat percentages required greater mechanical force to shear, than patties with 24% fat or greater. Also, panelists repor ted patties formulated to have 14% fat were drier than those formulated to have 24% fat or more. Neither report identified a difference in ground beef flavor at any fat inclusion percentage (Cross, Berry, and Wells, 1980; Berry and Leddy, 1984). Troutt, Hunt, Johnson, Claus, Kastner, Kropf and Stroda (1992) evaluated ground beef patties with fat percentages from 5 to 30 percent in 5% increments. These authors reported that low fat patties (5 and 10%), were less tender, both by sensory panel and objective measurements, and had lower sensory juiciness values than patties with 20 30% fat. Moreover, these authors reported that sensory panelists found patties with 5 or 10% fat were less flavorful than patties with 20 30% fat.

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27 Lean Color and Shelf life Demos and Mandigo (1996) as well as Raines, Hunt and Unruh (2009) have reported 80% lean ground beef patties were usually lighter (higher L*) than those patties formulated to 90% lean. Multiple researches have evaluated oxidative rancidity by measuring the th iobarbituric acid reactive substances (TBARS) of ground beef patties of varying lean percentages (Liu, Huffman, Egbert, McCaskey and Liu, 1991; Brewer, McKeith and Britt, 1992; Luchsinger, Kropf, Garcia Zepeda, Hunt, Stroda, Marsden, and Kastner, 1997; Bon d, Marchello, and Slanger, 2001). Liu, Huffman, Egbert, McCaskey and Liu (1991) and Bond, Marchello and Slanger (2001) formulated patties to 80 and 90% lean and both groups of researchers found no differences in the amount of oxidation between the two lea n percentages. Furthermore, Brewer, McKeith and Britt (1992) manufactured patties to 80 and 92% lean and also found no differences in oxidative rancidity. Luchsinger, Kropf, Garcia Zepeda, Hunt, Stroda, Marsden and Kastner (1997) formulated patties to 78 and 90% lean and measured oxidation using the TBARS method, and found no differences in oxidation between the two lean percentages.

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28 CHAPTER 3 EVALUATION OF GROUND BEEF QUALITY FROM CO MMODITY AND PREMIUM QUALITY TRIMMINGS Materials and Methods Raw Mat erials Raw materials for ground beef processing were collected at 48 h postmortem from a commercial beef processing facility on two sampling dates, for the two respective project replicates. Non fed, beef type cow carcasses (COW) and grain fed, beef typ e steer or heifer carcasses (FED) were identified and distinguished from grain fed, beef type cow carcasses and grain fed and non fed, dairy type cow carcasses, by utilizing carcass weight, subjective external fat thickness and color, and carcass conformat ion. The group of cattle that generated the FED carcasses all originated from the same privately owned feedyard and were fed the same ration. The cattle that generated the COW carcasses were selected from within the same slaughter lot for both sampling d ates. Skeletal maturity was determined by trained, University of Florida (UF) personnel as selection criteria, within COW and FED populations. All COW carcasses selected displayed E skeletal maturity and were estimated to be USDA Utility, while all FED carcasses selected displayed A skeletal maturity. The FED carcasses were ribbed between the 12th and 13th ribs by plant personnel, and USDA marbling score was used as a selection criteria by UF personnel within the FED population to identify two carcass t ypes, carcasses (n = 6, per date) were selected to have a Modest or Moderate degree of marbling (Top Choice; TC) and (n = 3, per date) were selected to have a Slight or Small degree of marbling, respectively (Commodity; COM). Hot carcass weight was record ed from carcasses of all populations, and for the FED carcasses, fat thickness and LM area were measured, the percentage of KPH fat was estimated, lean maturity

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29 and marbling score were evaluated by UF personnel for the calculation of USDA yield grades (USD A AMS, 1997). Ultimately, the right sides of 37 carcasses were selected for fabrication by plant personnel over the two sampling dates. Patty Manufacturing Untrimmed inside rounds (IMPS #168) and outside round flats (IMPS #171B) were collected from COW carcasses (n = 6 and 7) for replicate 1 and 2, respectively. These round subprimals, as well as boneless plates (IMPS #121) were collected from TC and COM carcasses (n = 6, per carcass type, per replicate), respectively. Round subprimals were used as a lean source and plates were used as a fat source, for ground beef processing. Raw materials arrived at the UF meat processing center under refrigerated storage on d 3 or 4 postmortem, from replicates 1 and 2, respectively. The following day, round subprim als were trimmed visually free of external fat prior to all lean and fat sources being ground through a 0.64 cm plate (AFMG 52, Biro Manufacturing Co., Marblehead, OH). A representative 6.7 kg sample from each lean and fat source was collected to determin e fat percentage in triplicate via American Oil Chemist Society approved procedure (# 5 04) using an ANKOM XT15 (Ankom Technology, Macedon, NY) to determine formulations for lean and fat source combinations (Table 3 1). The following day, lean and fat so urces were mixed and ground through a 0.32 cm plate to make 80 and 90 % lean patties representing all 12 combinations: lean source (3) fat source (2) lean percentage (2). One lean source fat source lean percentage combination from the first replic ate ultimately had an elevated fat percentage, due to apparent improper weighing, and was not utilized in any analysis. Fifty one 113 g patties (9.5 cm in diameter and 1.5 cm thick) were made per combination using a Patty O Matic Eazy Slider (Patty O Mat ic, Farmingdale, NJ). Patties (n = 37) were

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30 individually identified, placed in heat shrink vacuum bags (B2570; Cryovac, Duncan, SC), vacuum sealed (Multivac C500, Multivac Inc., Kansas City, MO) and frozen at 40C for assessment of d 0 oxidative rancidit y analysis via thiolbarbituric acid reactive substances (TBARS, n = 2), ANKOM fat analysis (n = 2), and Lee Kramer shear force (n = 5), consumer sensory analysis (n = 25) and trained sensory analysis (n = 3), respectively. The remaining patties (n = 14) w ere individually placed on 2 S Styrofoam trays (Genpack, Glens Falls, NY) containing a Dri Loc 40 g white meat pad (Sealed Air Corporation, Elmwood Park, NJ) and overwrapped with polyvinylchloride film (23,250mL of O2/m2/24hC/90% relative humidity) for obj ective and subjective retail color evaluation (n = 8), or were vacuum sealed and frozen as described previously after 1, 2, or 4 d of retail display for oxidative rancidity analysis (n = 2, per d). Packages (n = 96) were placed in a coffin style retail di splay case, and packages were rotated daily to compensate for uneven temperature and light distribution within the case. Fat Analysis A food processor (# 306 HandyChopper Plus, Black and Decker, Towson, MD) was used to process samples from each initial lean and fat source, and two patties from each combination were analyzed. Two g of each sample was placed, in duplicate, into a labeled filter bag, heat sealed, and weight was recorded as initial weight. Those samples were placed in a drying oven for 12 h, and then weighed, with weight being recorded as W1. Total lipid content was measured using hexane in an Ankom XT15 Extractor. After extraction, samples were again placed in a drying oven for 15 min, and then weighed, with weight being recorded as W2. Fat percentage was calculated by the difference in W1 and W2, divided by initial weight 100. The ultimate fat percentage for the two lean percentages, across two replicates and six lean source fat source combinations was 20.76 0.31 for 80% lean pa tties and 10.77 0.30 for 90% lean patties, respectively (Table 3 1)

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31 Retail Color Evaluation Ground beef was displayed in a Hill (Hill Refrigeration Div., Trenton, NJ) coffin style retail case at 2 + 3C for 4 d. Cases were illuminated with GE T8 Linea r Fluorescent lamps (2,800 lm, 4,100 K; General Electric Company, Fairfield, CT) that emitted a case average of 1,148 lx. Packages were rotated daily to compensate for uneven temperature and light distribution within the case. Using a whole number scale (AMSA, 2003), a 6 to 8 member trained panel evaluated each ground beef patty daily for 5 d, for lean color (1 = Extremely dark red, 2 = Dark red, 3 = Moderately dark red, 4 = Slightly dark red, 5 = Slightly bright cherry red, 6 = Moderately bright cherry r ed, 7 = Bright cherry red, 8 = Extremely bright cherry red) and percentage surface 79%; 6 = Extensive 99%; 7 = Complete = 100%). Objective lean color analysis (L*, a*, b*) was conducted on the surface of each ground beef patty daily for 5 d in duplicate and averaged using a Hunter Miniscan XE Plus (Hunter Laboratory, Reston, VA) with an illuminant setting of D65/10 with a 2.54 cm aperture. Hunter L*, a*, and b* values were then used to calculate hue angle, representing a change from the true red axis = (tan 1 {b*/a*}); chroma, representing the total color or vividness of col or = ((a* + b*) all of which were calculated according to standard equations (Minolta, 1998). Lipid Oxidation Lipid oxidation was only evaluated fro m patties made during the second replication. Lipid oxidation was determined by a modified method published by Buege and Aust (1978). A 10 g

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32 sample was taken from the patty surface (0.5 to 0.7 cm), placed in a Waring blender and homogenized with 30 mL of distilled water for 30 s. Meat homogenate was transferred to a 50 mL test tube and centrifuged at 1850Xg. Two mL of supernatant was placed in a test tube and 4 mL of a thiobarbituric acid/trichloroacetic acid (TBA/TCA) solution was added. Samples were pl aced in a boiling water bath for 15 min, allowed to cool in an ice bath for 10 min then centrifuged at 1850Xg. The absorbance of the supernatant was determined at 531 nm against a blank containing 2 mL distilled water and 4 mL TBA/TCA with a spectrophotom eter (ModelDU7500, Beckman Instruments Inc.). Cooking Frozen patties were cooked for all assessments on an open hearth, variable heat grill (Model 31605 AH, Hamilton Beach/Proctor Silex Inc., Southern Pines, NC). Patties were turned once at an internal temperature of 35 C and were allowed to finish cooking, reaching an internal temperature of 71 C (AMSA, 1995). For trained sensory and Lee Kramer shear force, temperature was monitored using copper constantan thermocouples placed in the geometric center of each patty connected to a recording thermometer (Measurement Computing Corp., Norton, MA) and recorded using DASYLab 12.0 in Windows 7 (Measurement Computing Corp., Norton, MA). For consumer sensory evaluation, temperatures were monitored during cooki ng using a hand held thermometer (Type K Microprocessor thermometer, Control Company, Friendswood, TX) according to the same cooking protocol. Trained Sensory Evaluation Panelists evaluated three patties from the 12 combinations over six sensory session s, for each replicate. Only one patty from each combination was allotted to each sensory event. Panelists evaluated 6 samples per event, 2 cubes (1.27 cm 3 ) per sample, served in warmed covered containers in a positive pressure ventilated room with lighti ng and cubicles designed for

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33 objective meat sensory analysis. A 7 11 member sensory panel trained according to AMSA sensory evaluation guidelines (AMSA, 1995) evaluated each ground beef sample on an eight point scale for beef flavor, juiciness, and firmne ss (1 = extremely bland, extremely dry, extremely soft to 8 = extremely intense, extremely juicy, extremely firm), on a six point scale for off flavor (1 = extreme off flavor to 6 = no off flavor detected) and on a five point scale for greasiness (1 = extr emely greasy to 5 = not greasy). Water and unsalted crackers were provided to panelists between samples for palate cleansing. Consumer Sensory Evaluation An email was sent to a list serve of University of Florida (UF) employees and students which had prev iously participated in consumer sensory panels at the Food Science and Human Nutrition building at UF. Over 100 consumers per replicate responded, with a total of 87 and 94 consumers ultimately consuming ground beef patties from the 12 lean source fat s ource lean percentage combinations, for the two replicates, respectively. Panelists attending all sessions per replicate were compensated with a $20 gift card. No consumers participated in both replicates. Consumer sensory evaluation was conducted ove r 4 d, for each respective replicate. A total of ten panel sessions were conducted on each day of evaluation, with no more than ten consumers scheduled to attend each session. For each day of evaluation, a given lean percentage was designated and patties from three lean source fat source combinations were chosen randomly. earlier for each panel session. Consumers were provided the three wedge shaped samples (one fifth of a patty) at the same time in individual plastic cups identified by a random, three digit code. Consumers evaluated all samples for flavor, juiciness, texture, and overall acceptability on a 9 point hedonic scale (1 = dislike extremely; 5 = neith er like nor dislike; 9 = like extremely) and assessed patty juiciness and firmness on a five point just about right (JAR) scale (1 = too

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34 juicy or soft; 2 = slightly too juicy or soft; 3 = just about right juiciness or firmness; 4 = slightly too dry or fir m; 5 = too dry or firm). Consumers were asked to cleanse their palates with tap water and a bite of a cracker between samples. Lee Kramer Shear Force Frozen weights of ground beef patties were taken prior to being cooked as described for trained sensory evaluation. Patties were blotted dry with a paper towel, and cooled to room temperature (25 C), and placed on trays, covered with PVC film and refrigerated in the dark at 4C for 12 h. A 6 6 cm portion was cut using a die from center of each patty. S hear force was determined with a Lee Kramer shear device attachment to an Instron Universal Testing Machine (Series IX Automated Materials Testing System, Model 245 A, Instron Corp., Canton, MA) with a 500 kg load cell and 500 mm/min travel speed. Statisti cs All data were analyzed as a full factorial design with 3 factors, lean source (3) fat source (2) lean percentage (2) using the mixed model procedure of SAS (SAS Inst., Inc., Cary, NC). The JAR scale was used to determine the percentage of consumer s who assessed the juiciness and firmness of patties as described by the lexicon. The binary data generated was analyzed with the GENMOD procedure of SAS utilizing lean source, fat source, and lean percentage as fixed effects. Sensory event was used as a random variable in the analysis of all other trained and consumer sensory traits. Replicate was used as a random variable in all models except for TBARS, and objective texture analysis, all of which were only assessed from replicate 2. Display day was included in the repeated measures analysis of objective and subjective retail evaluation, with retail package being the experimental unit. Least square means were calculated for main and interactive effects and separated statistically using pair wise t te sts (P DIFF option

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35 of SAS) when a significant ( P < 0.05) F test was detected. Additionally, the standard error (SE) for each main effect was reported. Results and Discussion Carcass Data Characteristics of beef carcasses used as lean source and fat sour ce for manufacturing beef patties is presented in Table 3 2. Average external fat thickness of COW carcasses at the 12 th rib interface would not have exceeded 0.50 cm, although these data were not collected. Raw Instrumental Color Patties formulated with COW lean were darker (lower L* values) than patties manufactured with either TC or COM lean throughout the retail display period, and patties formulated with all three lean sources behaved similarly throughout retail display (lean source day of retail d isplay, P = 0.002; Figure 3 1). On d 0 of retail display, patties made from COW lean were the most red (greatest a* values), the most truly red (greatest hue angle values), and produced the most vivid color (greatest chroma values) of the lean sources uti lized. Patties formulated with COW lean also had the greatest change for these traits, becoming less red, less truly red, and less vivid during retail display when compared to COM and TC lean patties. Patties with COW lean were comparable to COM and TC l ean patties for a*, hue angle, and vividness by d 4 of display, which displayed similar trends for these traits throughout display (lean source day of retail display, P < 0.001; Figure 3 1). Also, patties containing COW lean displayed greater total colo r change from d 0 (greater E values; P containing TC lean (9.04 vs. 5.67), which displayed greater values ( P containing COM lean (4.77; data not shown in table). Patties made with TC lean were less yellow (lowe r b* values) throughout the 5 d of retail display, while COW and COM lean patties followed similar trends (lean source day of retail display, P = 0.049; Figure 3 1).

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36 Myoglobin concentration in muscle increases with physiological age; therefore the dark er, redder color of the COW beef patties was expected (Graafhius and Devine, 1994; Shemeis, Liboriussen and Bech Anderson, 1994; Sawyer, Mathis and Davis, 2004). Patten, Hodgen, Stelzleni, Calkins, Johnson and Gwartney (2008) reported six of the nine musc les they evaluated were darker from cow carcasses than the same muscles from A maturity Select grade beef steers. However, contrary to the current study, animal age had little effect on beef redness. Multiple authors have reported beef from cow carcasse s to have greater pH values than beef from grain fed steers and heifers (Graafhuis and Devine, 1994; Patten, Hodgen, Stelzleni, Calkins, Johnson and Gwartney, 2008; Raines, Hunt and Unruh, 2009). The increase in ultimate pH is either due to lower glycogen reserves in the muscle and/or reduced fat coverage leading to faster cooling rates and slower postmortem pH fall (Faucitano, Chouinard, Fortin, Mandell, Lafreniere, Girard, and Bertiaume, 2008). Either hypothesis can be affected by diet and/or amount of antemortem energy expenditure. An elevated pH will increase lean darkness due to increased light absorbency (Hedrick et al., 1959). Additionally, the increased pH keeps myoglobin in the ferrous state, which also causes a darker lean color (Lawrie, 1958). However, this hypothesis is speculative, because pH was not evaluated in this report. The findings for objective color change display somewhat complement Raines, Hunt and Unruh (2009) who reported patties made with beef cow semimembranosus displayed great er change for a* and chroma values during 4 d of retail display than patties made from dairy cow semimembranosus, becoming less red and less truly red. Dairy cows generally have several similarities to grain fed, commercially raised, young steers and heif ers in than they are housed in confinement and offered a higher energy, concentrate based diet, all of which is generally different than beef cows. Increased exercise, typical of loose housed, non fed, beef cows,

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37 increases oxygen species in muscle and, th erefore, is conducive to greater meat discoloration Hunt and Unruh (2009) identified cattle as beef or dairy type after slaughter and the certain production systems were not known. Fat source did not affect lightness (L* values; P = 0.153), yellowness (b*values; P = 0.31) or color vividness (chroma values; P = 0.176) across retail display day and lean percentage (Table 3 3). Patties that contained COM as a fat sourc e were more red (greater a* values; P = 0.033) compared to patties using TC as a fat source (Table 3 3). Patties using TC as a fat source tended to have a greater increase in hue angle, becoming less truly red, from d 2 to d 3 of retail display than patti es using COM as a fat source (fat source day of retail display, P = 0.026; Figure 3 2). Patties containing TC fat and formulated to 80% lean, had the greatest total color change P lean percentage combination (fat source lean percentage, P = 0.007; Figure 3 3). Patties containing COM fat and formulated to 80% lean had greater total color change ( P containing the same fat at 90% lean, which had the least total color change during retail display ( P P = 0.007; Figure 3 3). The boneless beef plates used as the TC fat source came from carcasses which had a greater amount of 12 th rib fat than the plates used for the COM fat source. As cattle become fatter, the proportion of polyunsaturated fatty acids decreases and monounsaturated fatty acids increases generally improving lean color stability and decreasing suscept ibility to oxidation (Duckett, Wagner, Yates, Dolezal, and May, 1993). However, the percentage of stearic acid

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38 (18:0), a saturated fatty acid, also decreases as cattle fatten (Leat, 1975; Duckett, Wagner, Yates, Dolezal, and May, 1993). The reduced perce ntage of this saturated fat could be speculated to decrease lean color stability. Lean percentage had no effect on yellowness (b* values; P = 0.311), true redness (hue angle values; P = 0.187), or color vividness (chroma values; P = 0.105) across retail di splay (Table 3 3). Patties formulated to 80% lean were lighter (greater L* values; P < 0.001) and less red (lower a* values; P = 0.003) than patties formulated to 90% lean, across lean or fat source and day of retail display (Table 3 3). The effect of le an percentage on lightness, yellowness and vividness of patties agrees with the findings of Raines, Hunt and Unruh (2009), yet current study differs with the same authors for redness, who found lean percentage had little impact on the redness of patties wi thin the same display day. Subjective Color the same lean percentag e; however patties manufactured from COW lean produced the greatest decrease in lean color score during retail display (lean source x lean percentage day of retail display, P = 0.005; Figure 3 4). Patties formulated to 80% lean tended to have greater nu merical values for lean color (lean source x lean percentage day of retail display, P = 0.005; Figure 3 4). Lean source had little effect on percent discoloration of patties through d 3 of retail display, however; patties formulated with COW lean appea red to have greater discoloration than patties made with TC or COM lean by d 4 of retail display, regardless of lean percentage (lean source lean percentage day of retail display, P < 0.001; Figure 3 4). Similar to these results, Raines, Hunt and Unru h (2009) found that patties formulated with beef cow semimembranosus

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39 produced the most optimal visual color scores at d 0 and 1, but discolored more rapidly than patties made with dairy cow semimembranosus as retail display day progressed. Patties formul color throughout the retail display, when compared to 90% lean patties (fat source lean percentage day of retail display, P = 0.002; Figure 3 5). Raines, Hunt and Unruh (2009) found that patties formulated to 80% lean were brighter (greater L* values) throughout retail display day, when compared to 90% lean patties. The results for fat source on percent discoloration of patties through d 3 of retail display were similar to those for lean source, with all fat source lean percentage combinations being similar; however patties formulated with TC as a fat source tended to be more discolored than patties manufactured with COM as a fat source (fat source lean percentage day of re tail display, P = 0.413; Figure 3 5). It is important to note that this was not a statistically significant interaction. Thiobarbituric Acid Reactive Substances (TBARS) Rancidity values of patties did not differ on d 0 and were numerically lower than al l subsequent days of retail display, irrelevant of lean source (Figure 3 6) or fat source (Figure 3 7). than patties made with COM lean (lean source day of re tail display, P = 0.007; Figure 3 6). Rancidity values did not differ among lean sources after 2 d of retail display, but at the 0.043) than patties with COM or CO W as lean source, which did not differ (lean source day of retail display, P = 0.007; Figure 3 6). Rancidity values did not differ among fat sources after 1 d of retail display, but after 2 and 4 d of retail display, respectively, patties formulated wit h TC as

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40 source (fat source day of retail display, P = 0.002; Figure 3 7). Our results conflict with those of Raines, Hunt and Unruh (2009) who reported that pa tties made with dairy cow semimembranosus were more rancid at the end of retail display than patties made with beef cow semimembranosus. The reason for the differences in the current study could be attributed to the previously mention idea that products f rom the fatter TC carcasses could have a lower percentage of stearic acid, otherwise these differences are largely unexplainable. Consumer Sensory Consumer sensory panelists found no differences ( P acceptability of patties, regardless of lean source or fat source (Table 3 4). Similarly, Cross, Green, Stanfield and Franks (1976) reported no differences in overall acceptability for patties manufactured from either USDA C hoice or Good carcasses. However, they did find that patties manufactured from USDA Choice carcasses to be higher in overall acceptability than patties formulated from USDA Cutter carcasses. Additionally, approximately the same percentage of consumers fo und patties just about right (JAR) for juiciness and firmness, irrelevant of lean source (Table 3 4). A greater percentage of consumers reported patties formulated with TC fat as JAR for juiciness (49.13 vs. 37.96%) and firmness (62.19 vs. 51.36%), with consumers reporting patties manufactured with COM fat to be too dry and too firm (Table 3 4). Consumers gave 80% patties greater ratings for likeness of flavor ( P = 0.046), and tended to give them greater ratings for overall acceptability ( P = 0.062), co mpared to 90% lean patties (Table 3 4). A higher percentage of consumers rated 80% patties to be just about right for juiciness (55.24 vs. 32.77%) and firmness (63.67 vs. 50.2%) (Table 3 4), indicating that a higher fat level corresponds not only to incr eased juiciness and softness, but also an increase in consumer acceptability for these 80% lean products.

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4 1 Patties formulated with COM lean source and TC fat source received greater values for consumer liking of texture ( P = 0.002) than patties formulated with COM lean source and COM fat source, with all other treatments being the same (lean source x fat source, P = 0.002; Figure 3 8). Trained Sensory Trained sensory panelists found no differences for flavor, juiciness, off flavor, or greasiness for pat ties manufactured from different lean sources (P 0.307) or fat sources (P 0.131; Table 3 5). Also, fat source did not affect (P = 0.694) trained panelist perceptions of cooked patty texture (Table 3 5). Similarly, Berry and Abraham (1996) reported no differences in juiciness or beef flavor ratings for patties formulated from young or mature beef carcasses. Panelists found patties manufactured with TC as a lean source firmer (P = 0.027) than patties formulated with either COW or COM as a lean source, which were not different (Table 3 5). No differences in flavor (P = 0.251) were observed between 80 and 90% lean patties (Table 3 5). Previous findings also showed no differences in flavor ratings between similar fat percentages (Cross, Berry, and Wells 1980; Berry and Leddy, 1984). Trained panelists found 80% lean patties were juicier (P < 0.001), softer (P = 0.008), greasier (P = 0.004), and contained more off flavor (P = 0.027) than 90% lean patties (Table 3 5). These findings are in agreement with previous findings that show that as fat percentage increases juiciness increases, and firmness decreases (Berry, 1994; Berry and Leddy, 1984; Cross, Berry and Wells, 1980). Lee Kramer Shear Force Generally, 90% lean patties were tougher (higher numerica l Lee Kramer shear force value) than 80% patties (lean source x fat source x lean percentage, P = 0.003; Figure 3 9). These findings indicate that as lean percentage increase, so does Lee Kramer shear force, which complements the findings of the trained p anelists and has been well documented by previous

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42 researchers (Cross, Berry, and Wells, 1980; Berry and Leddy, 1984; Troutt, Hunt, Johnson, Claus, Kastner, Kropf and Stroda, 1992). other treatment combinations, except for patties made with COM lean and COM fat, which did not differ than patties made with COW lean (lean source fat source lean percentage, P = 0.003; Figure 3 9). Patties formulated to 90% with COW lean and COM fat than all other treatment combinations, except for patties made with TC lean and TC fat, which did not differ than patties made COW lean and COM fat (lean source fat source lean percentage, P = 0.003; Figure 3 9). Implication s Fat source had a marginal affect on the objective color of beef patties during retail display. Patties manufactured with COW as a lean source had greater subjective values for lean color and were objectively a more optimal red at the beginning of retail display, however, these patties also produced the greatest reduction in color stability by the conclusion of retail display. Trained sensory panelists found marginal or no differences in patties manufactured with different lean or fat sources. Additiona lly, trained sensory panelists found 80% lean patties to be juicier, softer, greasier and to contain more off flavor than 90% lean patties. Consumer panelists found no differences in likeability for overall acceptability or flavor between patties manufact ured with different lean or fat sources. Additionally, consumers preferred the flavor of 80% lean patties and tended to give 80% lean patties higher ratings for overall acceptability in comparison to 90% lean patties. Moreover, a higher percentage of con percent lean had lower Lee Kramer shear force values than patties manufactured to 90% lean. Lean source had a greate r influence than fat source on retail color. Furthermore, patties

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43 containing COW lean began retail display at a more ideal retail color, but declined more rapidly than TC or COM lean patties. Lean and fat source had marginal impact on consumer or trained sensory palatability.

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44 Table 3 1. Schematic of lean source, fat source, and lean percentage formulation for manufacturing ground beef patties Lean source b Fat source c COW TC COM TC 80 90 80 90 80 90 COM 80 90 80 90 80 90 a Evaluated in duplicate f rom two patties per combination via ANKOM extraction as: 80 = 20.76 0.31; 90 = 10.77 0.30 % fat, respectively. b 93.25 97.25 % lean beef product sourced from COW = USDA Utility carcasses; TC = A maturity carcasses with Modest or Moderate degrees of m arbling; COM= A maturity carcasses with Slight or Small degrees of marbling. c 55.0 59.0 % lean beef product sourced from TC = A maturity carcasses with Modest or Moderate degrees of marbling; COM = A maturity carcasses with Slight or Small degrees of m arbling.

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45 Table 3 2. Characteristics of beef carcasses used as lean source and fat source for manufacturing beef patties Carcass type a Trait COW TC COM No. of observations 13 12 12 Hot carcass wt, kg 288.7 51.7 340.6 39.0 335.4 39.0 12 th rib f at thickness, cm --1.63 0.58 1.56 0.63 LM area, cm 2 --78.33 7.0 78.39 9.55 USDA YG b --3.5 0.7 3.3 0.9 Lean Maturity c --155.0 33.2 159.2 17.3 Marbling d --550.8 35.3 404.2 48.1 a COW = non fed, beef type, cow carcasses with E skeletal maturity, estimated to be USDA Utility, used to generate COW lean source; TC = grain fed, beef type, A maturity steer or heifer carcasses with Modest or Moderate degrees of marbling, used to generate TC lean and fat source; Commodity = grain fed beef type, A maturity steer or heifer carcasses with Slight or Small degrees of marbling, used to generate COM lean and fat source. b Calculated according to USDA AMS, 1997 c 100 to 199 = A maturity. d 300 to 399 = Slight; 400 to 499 = Small; 500 to 599 = Modest.

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46 Table 3 3. Effect of fat source and lean percentage on objective color of beef patties. Fat source a P Diff Lean percentage P Diff Trait TC COM 80 90 L* b 40.75 0.16 41.07 0.15 0.153 44.02 0.15 37.80 0.16 < 0.001 a* b 14.69 0.3 5 15.71 0.32 0.033 14.48 0.35 15.92 0.32 0.003 b* b 16.92 0.75 17.97 0.70 0.31 16.92 0.75 17.96 0.70 0.311 Hue Angle c ------48.09 0.69 46.84 0.64 0.187 Chroma d 22.57 0.79 24.03 0.73 0.176 22.42 0.19 24.17 0.73 0.105 b 55.0 59.0 % lean beef product sourced from TC = A maturity carcasses with Modest or Moderate degrees of marbling; COM = A maturity carcasses with Slight or Small degrees of marbling. c L* = measure of darkness to lightness (larger value indicates a lighter c olor); a* = a measure of redness (larger value indicates a redder color); b* = a measure of yellowness (larger value indicates a more yellow color). d Hue angle represents the change from the true red axis (a larger number indicates shift from red to yello w). e Chroma is a measure of total color (a larger number indicates a more vivid color).

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47 Table 3 4. Effect of lean source, fat source and lean percentage on consumer sensory traits of beef patties. Lean source a P Diff Fat source b P Diff Lean percentage P Diff Trait COW TC COM TC COM 80 90 Overall acceptability c 6.08 0.14 6.02 0.14 6.02 0.14 0.754 6. 08 0.14 6.0 0.13 0.259 6.35 0.19 5.73 0.19 0.062 Flavor c 6.0 0.12 6.01 0.13 5.99 0.12 0.962 6.04 0.12 5.95 0.11 0.222 6.28 0.15 5.71 0.15 0.046 JAR juiciness d % 45.22 40.54 43.66 0.305 49.13 37.96 < 0.001 55.24 32.77 < 0.001 Too j uicy e % 3.98 4.55 4.98 0.301 4.75 4.27 0.282 7.69 1.7 < 0.001 Too dry f % 50.81 54.91 51.37 0.529 46.12 57.77 < 0.001 37.07 65.53 < 0.001 JAR firmness d % 57.14 54.20 57.14 0.432 62.19 51.36 < 0.001 63.67 50.2 < 0.001 Too soft e % 9.94 12.09 9.94 0.149 10.23 11.26 0.565 12.33 9.41 0.02 Too firm e % 32.92 33.71 32.9 0.774 27.58 37.39 < 0.001 24.00 40.39 < 0.001 a 93.25 97.25 % lean beef product sourced from COW = USDA Utility carcasses; TC = A maturity carcasses with Modest or Moderate degrees of marbl ing; COM= A maturity carcasses with Slight or Small degrees of marbling. b 55.0 59.0 % lean beef product sourced from TC = A maturity carcasses with Modest or Moderate degrees of marbling; COM = A maturity carcasses with Slight or Small degrees of marbl ing. c 9 = like extremely; 5 = neither like nor dislike; 1 = dislike extremely. d Percentage of consumers who determined patties as 3 = just about right. e Percentage of consumers who determined patties as 1 = too juicy or soft or 2 = slightly too juicy or soft. e Percentage of consumers who determined patties as 5 = too dry or firm or 4 = slightly too dry or firm.

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48 Table 3 5. Effect of lean so urce, fat source and lean percentage on trained sensory traits of beef patties. Lean source a P Diff Fat source b P Diff Lean percentage P Diff Trait COW TC COM TC COM 80 90 Flavor c 5.07 0.13 5.04 0.13 4.92 0.12 0.307 5.06 0.12 4.96 0.12 0.26 7 5.07 0.13 4.97 0.12 0.251 Juiciness c 4.69 0.13 4.58 0.13 4.54 0.13 0.339 4.67 0.12 4.54 0.12 0.131 4.87 0.12 4.33 0.12 < 0.001 Texture c 5.07 g 0.14 5.34 f 0.14 5.08 g 0.14 0.027 5.18 0.13 5.15 0.13 0.694 5.04 0.13 5.28 0.13 0.008 Off Flavor d 5.69 0.05 5.71 0.05 5.76 0.05 0.632 5.75 0.04 5.70 0.04 0.421 5.79 0.04 5.65 0.04 0.027 Greasiness e 4.69 0.04 4.67 0.05 4.68 0.04 0.978 4.67 0.04 4.69 0.03 0.712 4.60 0.04 4.76 0.03 0.004 a 93.25 97.25 % le an beef product sourced from COW = USDA Utility carcasses; TC = A maturity carcasses with Modest or Moderate degrees of marbling; COM= A maturity carcasses with Slight or Small degrees of marbling. b 55.0 59.0 % lean beef product sourced from TC = A mat urity carcasses with Modest or Moderate degrees of marbling; COM = A maturity carcasses with Slight or Small degrees of marbling. c 8 = extremely intense, extremely juicy, extremely firm, 1 = extremely bland, extremely dry, extremely soft d 6 = no off flav or detected, 1 = extreme off flavor e 5 = not greasy, 1 = extremely greasy fg Values lacking a common superscript within lean source are different ( P 0.023)

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49 a 93.25 97.25 % lean beef product sourced from COW = USDA Utility car casses; TC = A maturity carcasses with Modest or Moderate degrees of marbling; COM= A maturity carcasses with Slight or Small degrees of marbling. Figure 3 1. Interactive effect of lean source a and day of retail display on lightness (L*) values (P = 0.002 ), redness (a*) values (P < 0.001), yellowness (b*) values (P = 0.049), hue angle values (a larger number indicating a shift from red to yellow; (P < 0.001), and chroma values (a larger number indicates a more vivid color; P < 0.001) of beef patties.

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50 F igure 3 1. Continued

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51 a 55.0 59.0 % lean beef product sourced from TC = A maturity carcasses with Modest or Moderate degrees of marbling; COM = A maturity carcasses with Slight or Small degrees of marbling. Figure 3 2. Interactive effect of fat sour ce a and day of retail display on hue angle values (a larger number indicating a shift from red to yellow; P = 0.026) of beef patties.

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52 a 55.0 59.0 % lean beef product sourced from TC = A maturity carcasses with Modest or Moderate degrees of marbling; COM = A maturity carcasses with Slight or Small degrees of marbling. Figure 3 3. Interactive effect of fat source a values (a larger number indicates a greater change in total color from day 0, P = 0.00 7) of beef patties. Values within day of retail display lacking common letters

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53 a 93.25 97.25 % lean beef product sourced from COW = USDA Utility carcasses; TC = A maturity carcasses with Modest or Moderate degrees of marbling; COM = A maturity carcasses with Slight or Small degrees of marbling. b 1 = Extremely dark red, 2 = Dark red, 3 = Moderately dark red, 4 = Slightly dark red, 5 = Slightly bright cherry red, 6 = Moderately bright cherry red, 7 = Bright cherry red, 8 = Extremely b right cherry red. c 39%; 4 = 79%; 6 = Extensive 99%; 7 = Complete = 100%. Figure 3 4. Interactive effect of lean s ource a lean percentage and day of retail display on subjective lean color b values (P = 0.005) and subjective percent discoloration c values (P < 0.001) of beef patties.

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54 a 55.0 59.0 % lean beef product sourced from TC = A maturity carcasses with Modes t or Moderate degrees of marbling; COM = A maturity carcasses with Slight or Small degrees of marbling. b 1 = Extremely dark red, 2 = Dark red, 3 = Moderately dark red, 4 = Slightly dark red, 5 = Slightly bright cherry red, 6 = Moderately bright cherry red, 7 = Bright cherry red, 8 = Extremely bright cherry red. c 39%; 4 = 79%; 6 = Extensive 99%; 7 = Complete = 100%. Figure 3 5. Interactive effect of fat source a lean percentage and day of retail display on subjective lean color b values (P = 0.002) and percent discoloration c values (P = 0.413) of beef patties.

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55 a 93.25 97.25 % lean beef product so urced from COW = USDA Utility carcasses; TC = A maturity carcasses with Modest or Moderate degrees of marbling; COM= A maturity carcasses with Slight or Small degrees of marbling. Figure 3 6. Interactive effect of lean source and day of retail display on thiobarbituric acid reactive substances (TBARS) expressed as mg of malondialdehyde per kg of ground beef (P = 0.007). Values within day of retail display lacking common letters differ (P

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56 a 55.0 59.0 % lean beef product sourced from TC = A m aturity carcasses with Modest or Moderate degrees of marbling; COM = A maturity carcasses with Slight or Small degrees of marbling. Figure 3 7. Interactive effect of fat source a and day of retail display on thiobarbituric acid reactive substances (TBARS) expressed as mg of malondialdehyde per kg of ground beef (P = 0 .002). Values within day of retail display lacking common letters differ (P

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57 a 93.25 97.25 % lean beef product sourced from COW = USDA Utility carcasses; TC = A maturity carcasses with Modest or Moderate degrees of marbling; COM= A maturity carcasses with Slight or Small degrees of marbling. b 55.0 59.0 % lean beef product sourced from TC = A maturity carcasses with Modest or Moderate degrees of marbling; COM = A maturity carcasses with Slight or Small degrees of marbling. c 1 = dislike ext remely; 5 = neither like nor dislike; 9 = like extremely Figure 3 8. Interactive effect of lean source a and fat source b on the consumer perception of texture c (P = 0.027) of beef patties. Bars lacking a common letter differ (P = 0.002).

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58 a 93.25 97. 25 % lean beef product sourced from COW = USDA Utility carcasses; TC = A maturity carcasses with Modest or Moderate degrees of marbling; COM= A maturity carcasses with Slight or Small degrees of marbling. b 55.0 59.0 % lean beef product sourced from TC = A maturity carcasses with Modest or Moderate degrees of marbling; COM = A maturity carcasses with Slight or Small degrees of marbling. Figure 3 9. Interactive effect of lean source a fat source b and lean percentage on Lee Kramer shear force values (P = 0.003) of beef patties. Bars lacking a common letter within lean percentage differ (P 0.031).

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59 LIST OF REFERENCES 9 C.F.R §319.15 (2008). AMSA. (1995). Research guidelines for cookery, sensory evaluation and instrumental tenderness measurements of fr esh meat. Chicago, IL: American Meat Science Association and National Live Stock and Meat Board. Baublits, R.T., Brown, A.H., Pohlman, F.W., Johnson,, Z.B., Onks, D.O., Loveday, H.D., Morrow, R.E., Sandelin, B.A., Coblentz, W.K., Richards, C.J., & Pugh, R. B. (2004). Carcass and beef color characteristics of three biological types of cattle grazing cool season forages supplemented with soyhulls. Meat Science 68 (2), 297 303. Baublits, R.T., Brown, A.H., Pohlman, F.W., Rule, D.C., Johnson,, Z.B., Onks, D.O., Murrieta, C.M., Richards, C.J., Loveday, H.D., Sandelin, B.A., & Pugh, R.B. (2006). Fatty acid and sensory characteristics of beef from three biological types of cattle grazing cool season forages supplemented with soyhulls. Meat Science 72 (1), 100 107. Behrends, J. M., Mikel, W. B., Armstrong, C. L., & Newman, M. C. (2003). Color stability of semitendinosus, semimembranosus, and biceps femoris steaks packaged in a high oxygen modified atmosphere. Journal of Animal Science 81, 2230 2238. Bennett, L.L., Hammond, A. C., Williams M. J., Kunkle, W. E., Johnson, D. D., Preston, R. L., & Miller, M. F. (1995). Performance, carcass yield, and carcass quality characteristics of steers finished on rhizoma peanut ( Arachis glabrata ) tropical grass pasture or concen trate. Journal of Animal Science 73, 1881 1887. Berry, B. W. (1980). Effects of Chopping versus Grinding on Palatability, Shear, Chemical and Cooking Properties of Beef Patties. Journal of Animal Science 51, 615 619 Berry, B. W., Marshall, W. H., & Koch, E. J. (1981). Cooking and chemical properties of raw and precooked flaked and ground beef patties cooked from the frozen state. Journal of Food Science 46, 856 859. Berry, B. W. & Leddy, K. F. (1984). Effects of fat level and cooking method on sensory an d textural properties of ground beef patties. Journal of Food Sci., 49, 870 875. Berry, B. W., & Abraham, H. C. (1996). Sensory, shear force and cooking properties of commercially processed ground beef patties. Food Quality and Preference 7, 55 59. Bidner T.D., Schupp, N. R., Mohamad, A. B., Rumore, N. C., Montgomery, R. E., Bagley, C. P., & McMillin, K.W. (1986). Acceptability of beef from Angus Hereford or Angus Hereford Brahman steers finished on all forage or a high energy diet. Journal of Animal Scie nce 62, 381 387. Bond, J.M., Marchello, M.S., & Slanger, W.D. (2001). Physical, chemical, and shelf life characteristics of low fat ground beef patties formulated with waxy hull less barley. Journal of Muscle Foods 12, 53 69.

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65 BIOGRAPHICAL SKETCH Nicholas Myers was born in Oklahoma City, Oklahoma in 1988, the son of Kevin and Susan Myers. He was raised, alon g with his three sisters in Waynesboro, Tennessee. Nicholas worked on a cow calf operation, as well as a mixed animal veterinary practice in southern middle Tennessee. He graduated from Wayne County High School, Waynesboro, Tennessee in May 2006. While working on his undergraduate degree at Oklahoma State University, he participated on the intercollegiate meats judging team, as well as the meat animal evaluation team. Nicholas also worked at the Food and Agriculture Products Center (FAPC) meats laborato ry throughout the 2008 summer. Additionally, he participated in two internship programs in research and 2010, respectively. He received his Bachelor of Science degree in Food Industry in May 2010. He is currently a graduate teaching and research assistant finishing a Master of Science degree in the Department of Animal Sciences at the University of Florida.