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Quality of Carombola Fruit (Averrhoa carambola L.) as Affected by Harvest Maturity, Postharvest Wax Coating, Ethylene, a...

Permanent Link: http://ufdc.ufl.edu/UFE0024166/00001

Material Information

Title: Quality of Carombola Fruit (Averrhoa carambola L.) as Affected by Harvest Maturity, Postharvest Wax Coating, Ethylene, and 1-Methylcyclopropene
Physical Description: 1 online resource (137 p.)
Language: english
Creator: Warren, Oren
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2009

Subjects

Subjects / Keywords: 1mcp, arkin, aroma, averrhoa, carambola, ethylene, postharvest, stafruit
Horticultural Science -- Dissertations, Academic -- UF
Genre: Horticultural Science thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Carambola (Averrhoa carambola L.) fruits, also known as star fruit, are known for their unique shape. 'Arkin' is the major variety of carambola grown in Florida; it is popular because of its compact shape, which is favorable for shipping, and its natural sweetness. However, one problem at retail level is the poor appearance of the fruit. Another is the fruit is generally not as sweet as its potential. Currently carambolas are harvested at early ripeness (when color breaks or reaches 1/4 yellow) because fruit are firmer and less susceptible to mechanical injury during harvesting and shipping. But fruit harvested at the 1/2 yellow stage are known to be sweeter and have a significantly higher sugar-to-acid ratio than fruit harvested 1/4 yellow. This study was initiated to examine the potential for harvesting 'Arkin' carambola at more advanced ripeness stages using the following postharvest treatments:three color stages (1/4, 1/2, and 3/4 yellow), application of carnauba wax, ethylene, aqueous 1-methylcyclopropene (1-MCP) ethylene-action inhibitor, 1-MCP followed by ethylene, and storage at several temperatures. A price sensitivity analysis was also performed to determine the costs of adding a 1-MCP treatment to fruit produced in Florida. Storage at 5 C for 14 d did not induce chilling injury symptoms and slowed weight loss, color development, maintained firmness, suppressed total volatile formation, and extended shelf life up to 3 d. Waxing with a carnauba-based coating gave the fruit a more glossy appearance but slowed color development in the fins. Fruit harvested at the 1/4 yellow stage, waxed and held at 5 C for 14 d developed internal flesh browning; fruit harvested at the 1/2 and 3/4 yellow stage did not show these symptoms. Prestorage, exogenous ethylene treatment (100 ppm, 48 h, 20 C) slightly accelerated degreening of the fruit, while either 25 or 50 ppm treatment had no noticeable effect. However, after 14 d storage at 5 C the 100 ppm ethylene-treated fruit had ehigher incidence of fin-margin browning, and surface pitting/browning than the 25 and 50 ppm treated fruit. Fruit immersed in 50, 100 and 200 ug*L-1 aqueous 1-MCP for 1 min,delayed color development, notably in the fins of fruit harvested 1/4 yellow, and suppressed total volatile formation, especially norisoprenoid compounds that are associated with carotene degradation and over-ripe flavors. Fruit treated with 200 ug*L-1 were firmer and shelf life was extended for fruit harvested 1/4 or 1/2 yellow. This allows for a harvest at the 1/2 yellow (sweeter) stage. 1-MCP treatment followed by 14 d storage at 5 C then 100 ppm ethylene treatment for 24 or 48 h at 20 C was not beneficial in degreening the fins. The additional costs to packers for 1-MCP treatment were estimated from $0.25 to $3.50 per shipping carton and found to be feasible. The increased retail price per fruit was less than $0.40 in most scenarios and could be passed on to the consumer.
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 Oren Warren.
Thesis: Thesis (M.S.)--University of Florida, 2009.
Local: Adviser: Sargent, Steven A.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2011-05-31

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2009
System ID: UFE0024166:00001

Permanent Link: http://ufdc.ufl.edu/UFE0024166/00001

Material Information

Title: Quality of Carombola Fruit (Averrhoa carambola L.) as Affected by Harvest Maturity, Postharvest Wax Coating, Ethylene, and 1-Methylcyclopropene
Physical Description: 1 online resource (137 p.)
Language: english
Creator: Warren, Oren
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2009

Subjects

Subjects / Keywords: 1mcp, arkin, aroma, averrhoa, carambola, ethylene, postharvest, stafruit
Horticultural Science -- Dissertations, Academic -- UF
Genre: Horticultural Science thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Carambola (Averrhoa carambola L.) fruits, also known as star fruit, are known for their unique shape. 'Arkin' is the major variety of carambola grown in Florida; it is popular because of its compact shape, which is favorable for shipping, and its natural sweetness. However, one problem at retail level is the poor appearance of the fruit. Another is the fruit is generally not as sweet as its potential. Currently carambolas are harvested at early ripeness (when color breaks or reaches 1/4 yellow) because fruit are firmer and less susceptible to mechanical injury during harvesting and shipping. But fruit harvested at the 1/2 yellow stage are known to be sweeter and have a significantly higher sugar-to-acid ratio than fruit harvested 1/4 yellow. This study was initiated to examine the potential for harvesting 'Arkin' carambola at more advanced ripeness stages using the following postharvest treatments:three color stages (1/4, 1/2, and 3/4 yellow), application of carnauba wax, ethylene, aqueous 1-methylcyclopropene (1-MCP) ethylene-action inhibitor, 1-MCP followed by ethylene, and storage at several temperatures. A price sensitivity analysis was also performed to determine the costs of adding a 1-MCP treatment to fruit produced in Florida. Storage at 5 C for 14 d did not induce chilling injury symptoms and slowed weight loss, color development, maintained firmness, suppressed total volatile formation, and extended shelf life up to 3 d. Waxing with a carnauba-based coating gave the fruit a more glossy appearance but slowed color development in the fins. Fruit harvested at the 1/4 yellow stage, waxed and held at 5 C for 14 d developed internal flesh browning; fruit harvested at the 1/2 and 3/4 yellow stage did not show these symptoms. Prestorage, exogenous ethylene treatment (100 ppm, 48 h, 20 C) slightly accelerated degreening of the fruit, while either 25 or 50 ppm treatment had no noticeable effect. However, after 14 d storage at 5 C the 100 ppm ethylene-treated fruit had ehigher incidence of fin-margin browning, and surface pitting/browning than the 25 and 50 ppm treated fruit. Fruit immersed in 50, 100 and 200 ug*L-1 aqueous 1-MCP for 1 min,delayed color development, notably in the fins of fruit harvested 1/4 yellow, and suppressed total volatile formation, especially norisoprenoid compounds that are associated with carotene degradation and over-ripe flavors. Fruit treated with 200 ug*L-1 were firmer and shelf life was extended for fruit harvested 1/4 or 1/2 yellow. This allows for a harvest at the 1/2 yellow (sweeter) stage. 1-MCP treatment followed by 14 d storage at 5 C then 100 ppm ethylene treatment for 24 or 48 h at 20 C was not beneficial in degreening the fins. The additional costs to packers for 1-MCP treatment were estimated from $0.25 to $3.50 per shipping carton and found to be feasible. The increased retail price per fruit was less than $0.40 in most scenarios and could be passed on to the consumer.
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 Oren Warren.
Thesis: Thesis (M.S.)--University of Florida, 2009.
Local: Adviser: Sargent, Steven A.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2011-05-31

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2009
System ID: UFE0024166:00001


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1 QUALITY OF CARAMBOLA FRUIT ( A verrhoa carambola L.) AS AFFECTED BY HARVEST MATURITY, POSTHARVEST WAX COATING, ETHYLENE, AND 1METHYLCYCLOPROPENE By OREN WARREN 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 2009

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2 2009 Oren Warren

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3 To Valerie.

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4 ACKNOWLEDGMENTS I would like to express my sincere gratitude to Dr. Steve n Sargent as the supervisory chair of my committee for his continuous guidance, support and encouragement I would also like to thank the members of my committee; Dr. Donald Huber, Dr. Jeffrey Brecht, and Dr. Allen Wysocki for their guidance and suggestio ns. I wish to thank Mr. Kevin Bryan of Brooks Tropicals for his support in organizing and coordinating specific harvests of carambola. I also wish to thank Brooks Tropicals (Homestead, FL) for their generosity in supplying all of the fruit used in these ex periments. I owe my sincere thanks to Adrian Berry, our senior biological scientist, for her helpful assistance with lab methods and statistical analysis. Also, I would like to thank senior biological scientist Kim Cordasco for her help setting up my gassi ng experiments. I would like to especially like to thank my fellow graduate students for their assistance and friendship. I must thank Dr. Elizabeth Baldwin, Dr. Anne Plotto, and Tim Tillman of the USDA for their assistance in running and analyzing my vol atile samples, and for their suggestions for presenting the data. I would like to thank my m other and g randmother for providing me with a solid education and also guiding and inspiring me to attend graduate school. Finally, my deepest gratitude and love to Valerie for her patience, time, assistance with laboratory analysis, and constant encouragement during my entire college career

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5 TABLE OF CONTENTS page ACKNOWLEDGMENTS ...............................................................................................................4 LIST OF TABLES ...........................................................................................................................9 LIST OF FIGURES .......................................................................................................................12 LIST OF ABBREVIATIONS ........................................................................................................13 ABSTRACT ...................................................................................................................................14 CHAPTER 1 INTRODUCTION ..................................................................................................................16 2 REVIEW OF LITERATURE .................................................................................................19 Carambola ...............................................................................................................................19 Cost of Carambola Production in Florida ........................................................................21 Carambola Orchard Recovery Post Hurricane Andrew ..................................................22 Consumers and Retailers .................................................................................................23 Physiology, Harvesting and Storage ................................................................................23 Flavo r and Volatiles ........................................................................................................25 Antioxidants and Health Effects ......................................................................................27 Waxes and Edible Coatings .............................................................................................27 Ethylene ...........................................................................................................................28 1Methylcyclopropene (1 MCP) .....................................................................................30 Research Objectives ................................................................................................................32 3 POSTHARVEST QUALITY AS AFFECTED BY HARVEST MATURITY, STORAGE TEMPERATURE, AND WAX COATING ........................................................33 Introduction .............................................................................................................................33 Material and Methods .............................................................................................................34 Plant Material ..................................................................................................................34 Preparation and Treatments .............................................................................................34 Determination of Respiration Rate and Ethylene Production .........................................35 Ripening and Marketability .............................................................................................35 Compositional Analyses ..................................................................................................36 Soluble Solids Content (SSC), Total Titratable Acidity (TTA) and pH .........................36 Statistical Analysis ..........................................................................................................36 Results .....................................................................................................................................37 Respiration .......................................................................................................................37 Ethylene Production ........................................................................................................37 Weight Loss .....................................................................................................................37 Appearance ......................................................................................................................38

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6 Compositional Analyses ..................................................................................................38 Discussion ...............................................................................................................................39 Respiration and Ethylene Production ..............................................................................39 Weight Loss .....................................................................................................................39 Color and Flavor ..............................................................................................................40 Appearance ......................................................................................................................40 Conclusions .............................................................................................................................41 4 EFFECTS OF HARVEST MATURITY ON THE EDIBLE QUALITY AND AROMA PROFILE OF ARKIN CARAMBOLA ...............................................................................48 Introduction .............................................................................................................................48 Material and Methods .............................................................................................................49 Plant Material ..................................................................................................................49 Preparation for Compositional Analyses .........................................................................50 Firmness ..........................................................................................................................50 Total Sugars Content assay .............................................................................................50 Volatiles ...........................................................................................................................51 Results .....................................................................................................................................53 Firmness ..........................................................................................................................53 Compositional Parameters ...............................................................................................53 Total Sugars .....................................................................................................................54 Volatiles ...........................................................................................................................54 Discussion ...............................................................................................................................55 Firmness ..........................................................................................................................55 Compositional Analysis ...................................................................................................56 Total Sugars .....................................................................................................................56 Volatiles ...........................................................................................................................57 Conclusions .............................................................................................................................57 5 EFFECT OF POSTHARVEST EXOGENOUES ETHYLENE ON THE EDIBLE QUALITIES AND AROMA PROFILE OF ARKIN CARAMBOL A ................................62 Introduction .............................................................................................................................62 Material and Methods .............................................................................................................63 Plant Material ..................................................................................................................63 Ethylene Treatment and Storage Regime ........................................................................63 Days to Orange ................................................................................................................63 Firmness ..........................................................................................................................64 Volatiles ...........................................................................................................................64 Results .....................................................................................................................................64 Days to Orange Stage ......................................................................................................64 Appearance ......................................................................................................................64 Weight Loss .....................................................................................................................65 Firmness ..........................................................................................................................65 Compositional Ana lysis ...................................................................................................65 Volatiles ...........................................................................................................................66

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7 Discussion ...............................................................................................................................67 Days to Orange ................................................................................................................67 Appearance ......................................................................................................................67 Weight Loss .....................................................................................................................68 Compositional Analysis ...................................................................................................68 Volatiles ...........................................................................................................................69 Conclusions .............................................................................................................................69 6 INFLUENCE OF AQUEOUS 1 METHYLCYCLOPOPENE APPLICATION TO ARKIN CARAMBOLA FRUIT FIRMNESS AND VOLATILE PROFILE ......................75 Introduction .............................................................................................................................75 Material and Methods .............................................................................................................76 Plant Material ..................................................................................................................76 Treatment with Aqueous 1MCP .....................................................................................76 Quality Analyses .............................................................................................................77 Firmness ..........................................................................................................................77 Statistical Analyses ..........................................................................................................77 Results: Experiment 1 ............................................................................................................77 Respiration .......................................................................................................................77 Days to Peak Ripeness and Weight Loss ........................................................................78 Appearance Ratings .........................................................................................................78 Firmness ..........................................................................................................................78 Compositional Analysis ...................................................................................................79 Volatiles ...........................................................................................................................79 Discussion: Experiment 1 .......................................................................................................80 Respiration .......................................................................................................................80 Days to Peak Ripeness and Weight Loss ........................................................................80 Appearance Ratings .........................................................................................................81 Firmness ..........................................................................................................................81 Compositional Analysis ...................................................................................................81 Volatiles ...........................................................................................................................81 Results: Experiment 2 .............................................................................................................82 Respiration .......................................................................................................................82 Days to Peak Ripeness and Weight Loss ........................................................................82 Appearance Ratings .........................................................................................................83 Firmness ..........................................................................................................................83 Compositional Analysis ...................................................................................................83 Discussion: Experiment 2 .......................................................................................................84 Respiration .......................................................................................................................84 Days to Peak Ripeness and Weight Loss ........................................................................84 Appearance Ratings .........................................................................................................84 Fir mness ..........................................................................................................................85 Compositional Analysis ...................................................................................................85 Conclusions .............................................................................................................................86

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8 7 EFFECTS OF P OSTHARVEST TREATMENTS OF AQUEOUS 1 MCP AND ETHYLENE TO ARKIN CARAMBOLA FRUIT QUALITY ...........................................98 Introduction .............................................................................................................................98 Material and Methods .............................................................................................................99 Plant Material ..................................................................................................................99 Treatment with Aqueous 1MCP .....................................................................................99 Storage and Ethylene Treatment .....................................................................................99 Quality Analyses ...........................................................................................................100 Statistical Analyses ........................................................................................................100 Results ...................................................................................................................................100 Days to Peak Ripeness and Weight Loss ......................................................................100 Appearance Ratings .......................................................................................................100 Firmness ........................................................................................................................101 Compositional Analysis .................................................................................................101 Volatiles .........................................................................................................................102 Discussion .............................................................................................................................103 Days to Peak Ripeness and Weight Loss ......................................................................103 Appearance Ratings .......................................................................................................103 Firmness ........................................................................................................................104 Compositional Analysis .................................................................................................104 Volatiles .........................................................................................................................105 Conclusions ...........................................................................................................................105 8 COST OF APPLYING 1 MCP TO PERMIT TREERIPE HARVEST OF ARKIN CARAMBOLA IN FLORIDA .............................................................................................113 Introduc tion ...........................................................................................................................113 Methods ................................................................................................................................115 Results ...................................................................................................................................117 Discussion .............................................................................................................................117 Conclusions ...........................................................................................................................117 9 CONCLUSIONS AND SUGGESTIONS FOR FURTHER RESEARCH ..........................122 APPENDIX ..................................................................................................................................125 OUTPUT from Volatile analysis using a gas chromatogram ......................................................125 LIST OF REFERENCES .............................................................................................................130 BIOGRAPHICAL SKETCH .......................................................................................................137

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9 LIST OF TABLES Table page 31 List of carambola appearance categories an d subjective rating definition .......................44 32 Weight loss for Akin carambola after storage. ................................................................46 33 Subjective appearance ratings for Arkin carambola at the ora nge stage harvested at different maturities and stored at different temperatures ...................................................47 34 Selected compositional quality parameters for Arkin carambola harvested at three ripeness stages, ana lyzed at full ripe stage. .......................................................................47 41 Initial compositional parameters of Arkin carambola harvested at five maturities. .......59 42 To tal sugars of Arkin carambola harvested at three maturities. ......................................59 43 Volatile profiles of Arkin carambola harvested at five maturities. .................................60 51 Average days required for fruit to turn orange after harvest at three maturities, treated with ethylene and stored at 20 o C. ..........................................................................71 52 Appearance ratings for Arkin carambol a fruit treated with ethylene once reaching the orange stage. .................................................................................................................71 53 Weight loss for fruit upon reaching the orange stage. .......................................................72 54 Selected compositional quality parameters for Arkin carambola harvested at three color stages, treated with ethylene, and analyzed at full ripe stage ...................................72 55 Headspace aroma volatiles fo r Arkin Carambola harvested at 1/4 and1/2 yellow, in relationship with ethylene treatment and harvest maturity, analyzed at fullripe stage. ....73 61 Days taken to reach 1/4 orange stage and weight loss for Arkin carambola after treatment with aqueous 1 MCP plus 14 d at respective storage temperature plus ripening at 20 o C. ...............................................................................................................89 62 Subjective appearance ratings for Arkin caram bola fruit subjected to 1MCP treatments and various storage temperatures. Fruit rated once upon reaching the peak ripeness stage (1/4 orange). ................................................................................................90 63 Firmness (maximum force through 7 mm of a 10 mm of cross section) of Arkin carambola fruit at initial stages and upon reaching the peak ripeness stage. .....................91 64 Selected compositional quality parameters for Arkin carambola harves ted at three ripeness stages, treated with 1 MCP, and analyzed at the peak ripeness stage .................91

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10 65 Headspace aroma volatiles (relative areas) analyzed at the peak ripeness stage (1/4 orange) fo r Arkin carambola harvested 1/4 and 1/2 yellow, as affected by 1MCP treatment and harvest maturity. ..........................................................................................92 66 Days taken to reach 1/4 orange stage and weight loss for Arkin carambola after treatment with aqueous 1 MCP plus 14 d at respective storage temperature plus ripening at 20 o C. ...............................................................................................................95 67 Subjective appearance ratings for Arkin carambola fruit subjected to 1MCP treatments of different concentrations and two storage temperatures. Fruit rated once upon reaching the peak ripeness stage. .............................................................................96 68 Firmness (maximum force throught 7 mm of a 10mm cross section) of Arkin carambola fruit at initial stages and upon reaching the peak ripeness stage. ....................96 69 Selected compositional quality parameters for Arkin carambola harvested at three ripeness stages, treated with 1 MCP at three concentrations, and analyzed at the peak ripeness stage ....................................................................................................................97 71 Days to reach 1/4 orange stage and weight loss for Arkin carambola after treatment with aqueous 1MCP, 14 d storage at respective temperature, and ethylene treatment at 20 o C. ............................................................................................................................106 72 Subjective appearance ratings for Arkin carambola fruit subjected to 1MCP treatments at 5 and 20 o C. Fruit rated once reaching the peak ripeness stage. ................107 73 Firmness of Arkin carambola fruit at initial stages and upon reaching the peak ripeness stage ..................................................................................................................109 74 Selected compositional quality parameters for Arkin carambola harvested at three harvest maturities, treated with 1 MCP and ethylene, and analyzed at the peak ripeness stage ..................................................................................................................110 75 Headspace aroma volatiles for Arkin Carambola harvested at 1/4 yellow, as affected by 1 MCP treatment, storage at 5 o C, and ethylene treatment analyzed at full ripe stage. ..................................................................................................................111 76 Headspace aroma volatiles for Arkin carambola harvested at 1/2 yellow as affected by 1 MCP treatment, storage at 5 o C, and ethylene treatment analyzed at full ripe stage. ................................................................................................................................112 81 For a box of 20 the e stimated retail price per fruit of 1 MCP treated carambola, including a range of markup percentages ........................................................................119 82 For a box of 25 the e stimated retail price per f ruit of 1 MCP treated carambola, including a range of markup percentages. .......................................................................120

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11 83 For a box of 30 the e stimated retail price per fruit of 1 MCP treated carambola, including a range of markup percentages .......................................................................121

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12 LIST OF FIGURES Figure page 31 Appearanc e defects of Arkin carambola. ........................................................................42 32 Carambola maturity stages. ................................................................................................43 33 Combined respiration rates of unwaxed and waxed Arkin carambola during ripening at 20 o C, harvested at 1/4 yellow stage .. ..............................................................45 34 Ethylene production rates of waxed and control Arkin carambola harvested at 1/4 yellow during ripening at 20 o C .........................................................................................45 35 Internal browning of Arkin carambola harvested at one quarter yellow, waxed, and stored at 5 o C for 14 d. .......................................................................................................46 41 Firmness of Arkin carambola harvested at five maturities ............................................59 61 Respiration rate of Arkin carambola harvested at 1/4 yellow stage during ripening at 20 o C.. .............................................................................................................................87 62 Respiration rate of Arkin carambola harvested a t three stages of maturity and stored at 20 o C. Three days after treatment .. ......................................................................88 63 Respiration rate of Arkin carambola harvested at 1/2 yellow stage during ripening at 20 o C.. .............................................................................................................................94 A 1 Kovats retention index .....................................................................................................125 A 2 Gas chromatograph of an initial sample harvested in the 1/4 yellow stage.. ...................126

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13 LIST OF ABBREVIATIONS oC Degrees Celcius 1MCP 1methylcyclopropene C2H4 Ethylene CO2 Carbon dioxide cv. Cultivated variety, cultivar d D ay h Hour MAP Modified a tmosphere p ackaging m in Minute N Newtons NaCl Sodium chloride n.d. Not detected RH Relative humidity RI Kovats r etention i ndex SSC Soluble s olids c ontent TSS Total soluble sguars TTA Total t itratable a cidity

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14 Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the R equirements for the Degree of Master of Science QUALITY OF CARAMBOLA FRUIT ( Averrhoa carambola L.) AS AFFECTED BY HARVEST MATURITY, POSTHARVEST WAX COATING, ETHYLENE, AND 1METHYLCYCLOPROPENE By Oren Warren May 2009 Chair: Steven A. Sar gent Major: Horticultural Science Carambola ( Averrhoa carambola L.) fruits, also known as star fruit, are known for their unique shape. Arkin is the major variety of carambola grown in Florida; it is popular because of its compact shape which is favor able for shipping and its natural sweetness. However, one problem at retail level is the poor appearance of the fruit. Another is the fruit is generally not as sweet as its potential. Currently carambolas are harvested at early ripeness (when color breaks or reaches 1/4 yellow) because fruit are firmer and less susceptible to mechanical injury during harvesting and shipping. But fruit harvested at the 1/2 yellow stage are known to be sweeter and have a significantly higher sugar to acid ratio than fruit ha rvested 1/4 yellow. This study was initiated to examine the potential for harvesting Arkin carambola at more advanced ripeness stages using the following postharvest treatments : three color stages (1/4, 1/2, and 3/4 yellow), application of carnauba wax, ethylene, aqueous 1methylcyclopropene (1 MCP) ethylene action inhibitor 1MCP followed by ethylene and storage at several temperatures A price sensitivity analysis was also performed to determine the costs of adding a 1MCP treatment to fruit produced in Florida.

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15 Storage at 5 oC for 14 d did not induce chilling injury symptoms and slowed weight loss, color development, maintained firmness, suppressed total volatile formation, and extended shelf life up to 3 d. Waxing with a carnauba based coating gave the fruit a more glossy appearance but slowed color development in the fins. Fruit harvested at the 1/4 yellow stage waxed and held at 5 oC for 14 d developed internal flesh browning; fruit harvested at the 1/2 and 3/4 yellow stage did not show these symptoms. Prestorage, exogenous e thylene treatment ( 100 ppm 48 h, 20 oC ) slightly accelerated degreen ing of the fruit while either 25 or 50 ppm treatment had no noticeable effect. However, a fter 14 d storage at 5 oC the 100 ppm ethylene treated fruit had e higher incidence of fin margin browning, and surface pitting/browning than the 25 and 50 ppm treated fruit Fruit immersed in 50, 100 and 200 ug*L1 aqueous 1MCP for 1 min ,delayed color development notably in the fins of fruit harvested 1/4 yellow, and s uppressed total volatile formation especially norisoprenoid compounds that are associated with carotene degradation and over ripe flavors Fruit treated with 200 ug*L1 were firmer and s helf life was extended for fruit harvested 1/4 or 1/2 yellow. This al lows for a harvest at the 1/2 yellow (sweeter) stage. 1 MCP treatment followed by 14 d storage at 5 oC then 100 ppm ethylene treatment for 24 or 48 h at 20 oC was n ot beneficial in degreening the fins. The additional costs to packers for 1MCP treatment w e re estimated from $0.25 to $3.50 per shipping carton and found to be feasible The increased retail price per fruit was less than $0.40 in most scenarios and could be passed on to the consumer

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16 CHAPTER 1 INTRODUCTION The carambola ( Averrhoa carambola L. ) has been cultivated in tropical and subtropical regions for hundreds of years. The fruits are berries that originate from the ovary of the flower and usually have 46 fins (5 being the most common). The fruits are very fragile and are susceptible to wind scarring while growing on the tree. The size of a fruit ranges from 7.5 to 12.5 cm and is has a yellow to orange appearance some varieties have a whitish appearance. Production in the U.S. is limited to Hawaii and Florida. In Florida, the major cultivar is Arkin. Arkin is popular because of its sweet flavor and compact fin shape. The Arkin cultivar constitutes 95% of the Florida crop, other varieties grown are B10, Kary, and Golden Star (Crane, 1994). Currently there are approximately 200 acre s of commercial production in Florida, down from a high of 650 acres in 1992 (Kahout, 2004; J.H. Crane, Personal communication, 2007). The Florida tropical fruit industry has approximate combined annual value of $75 million. Carambola constitutes ~13 % of this value with revenue of $9.5 million a year (Kahout, 2004; and Crane recent estimates) The cv. Arkin makes up 95 % of the Florida crop. Arkin is popular because of its natural sweetness and compact fin shape. Astringent varieties are undesirable and varieties with long and thin fins are too fragile to withstand harvesting and packing. The physical appearance of carambola fruit at the retail level is a major postharvest problem. Currently carambolas are harvested at the one quarter yellow stage, while the fruit are still firm, to avoid mechanical damage from harvesting and handling. When fruits are harvested early in their maturity the ir appearance is more susceptible to symptoms of chilling injury and they take longer to reach their peak ripeness All of the mechanical and physiological injuries

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17 that the fruit ha ve sustained cause the appearance to deteriorate and provide sites for pathogens to enter Improper storage conditions also contribute to the appearance problems of carambola (Kader, 2002) There are techniques that can be used to extend the shelf life of fruit harvested at later maturity stages, as well as maintain the quality of the fruit postharvest. Edible wax coatings are commonly used on fruit to retain water and limit respiration. W ater loss is a problem because it leads to a loss in saleable weight, also known as shrinkage. Storing carambola in high relative humidity conditions helps to slow water loss and maintain firmness (Ali et al., 2004). High humidity storage is impractical in most commercial settings; therefore, creating a modified atmosphere by waxing the fruit might prove advantageous. Ethylene has been used commercially to hasten ripening and promote a uniform appearance of fruit (Reid, 2002). Ethylene is associated with t wo systems within plant physiology. System 1 is initiated by stress or injury and results in an increase in respiration and chlorophyllase activity. An increase in chlorophyllase activity in fruits leads to degreening (Amir Shapira et al., 1987). Chlorophy ll continues to degrade after an ethylene exposure (Purvis and Barmore, 1981).A postharvest ethylene treatment can start a degreening process that continues until the fruit are in a retail setting. The effectiveness of ethylene as a degreening treatment fo r green carambola has been investigated and the results were promising ( Miller and McDonald, 1997; Sargent and Brecht, 1990). 1methylcyclopropene (1 MCP) has been used commercially to delay ripening and senescence in many fruits and vegetables. Studies o n the effects of 1 MCP on carambola are limited to gaseous application and the variety Fwang Tung. 1MCP has not been used

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18 commercially on carambola in the U.S. 1MCP works by binding to ethylene receptor sites and preventing ethylene from binding with t he site (Sisler et al., 1996). This study investigates the potential to extend shelf life and maintain postharvest quality of commercially grown Arkin carambola. Experiments were performed to evaluate the effects of harvest maturity, storage temperatur e, edible wax coating, postharvest ethylene, and 1MCP treatments.

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19 CHAPTER 2 REVIEW OF LITERATURE Carambola The carambola ( Averrhoa carambola L.) originated in Southeast Asia, and has been cultivated in tropical and subtropical regions for hundreds of y ears. Carambola is also known as star fruit in the US T here are other names including: five corners, five fingers, and numerous nonEnglish names. One of the most interesting nonEnglish names comes from the Philippines where it is called balembing or belimbing which is an idiom also used to describe politicians who seem to have having multiple faces. Carambola is a memb er of the Oxalidaceae family. T he fruit is a berry that originates from the ovary and usually has 46 fins (5 being the most common). Other members of the family include bilimbi ( Averrhoa bilimbi L.), also known as the tree cucumber, and wood sorrels (Oxalis sp.). Bilimbi fruit are similar to carambola but their shape is rounded like a cucumber. Sorrels are herbaceous annuals that can b ecome a nuisance weed in greenhouses because the seed pods are explosively dehiscent. When the seed pod is mature the slightest agitation will send seeds flying into adjacent pots. The evergreen trees of carambola grow in tropical and subtropical regions In the US it is often sliced and used as a garnish for salads tropical fruit drinks and sometimes made into wine. The fruit is also salted and pickled, cooked in puddings, mixed into curries, stewed with sugar and cloves, made into preserves and jams, cooked with fish (China), boiled with shrimp (Thailand), or sliced and dried. The juice of the fruit has a light refreshing flavor and is popular in Malaysia. There is potential for the fruit to be lightly processed and used in the freshcut industry as it has an attractive star shape when sliced transversely but preventing oxidative browning is imperative (Weller et al., 2006)

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20 Significant production of carambola occurs in Taiwan, Malaysia, China, India, Philippines, Australia, India, Israel, Brazil, Peru, Guyana, and The United States (Florida and Hawaii). Carambolas are usually consumed in the country they are produced, except for high qu ality carambolas grown in Malaysia that are exported to Europe. The carambola was introduced to Florida in 1887 and at that time all of the available varieties were tart. In Florida carambola is grown in home landscapes as well as commercially in Miami Dade, Lee, Broward, and Palm Beach counties (Crane, 1994). Currently in Florida, approximately 81 hectares ( 200 acres ) ar e in commercial production, down from approximately 650 acres in 1992 (Kahout, 2004; J.H.Crane, Personal communication, July 13, 2007). Carambolas are very susceptible to mechanical damage. Movement from wind results in considerable scarring and damage. Sl ight scratching of the fruit while on the tree leads to unattractive fruit at the retail level as scars get darker and more pronounced with storage. Production in Florida requires windbreaks and wind sc reens which prevent wind from disturbing fruit while on the trees. Fr uit that swing while on the tree rub against other fruit and branches which causes mechanical damage Windbreaks usually consist of mature Australian pine ( Casuarina equisetifolia). The windscreens are made of wooden poles or more commonly a luminum poles with cables that support shade cloth. Tropical fruit production in Florida has an annual value near $75 million. Carambola production is approximately 4.5 million pounds per year. This constitutes 13% of the total annual revenues for Florida s tropical fruit industry, with a value approaching $9.5 million (Kahout, 2004, and Crane recent estimates). While in its native tropical habitat carambola trees bear fruit all year long, in Florida, the crop has two major harvesting seasons, August to Se ptember and December to February. The trees can be manipulated to fruit in the off season by pruning branches and thinning the young fruit set. This practice could add significant value to the crop by

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21 extending the season since there is no Florida grown ca rambola from March to July. Nunez Elisa and Crane (2000) found that pruning in July and September increased panicles of flowers by 14 and 20 % respectively, and that pruning in other months also proved successful. Arkin, a sweet variety of carambola was selected in the 1970s by Morris Arkin, an amateur propagator, of Coral Gables who grew plants from seeds and plant material that were collected in Thailand and Malaysia. Currently, approximately 95% of the Florida carambola crop is the cultivar Arkin, w hile the remaining plantings are B 10 and Kary (J.H. Crane Personal communication, 2007). B10 carambolas are sweet with good flavor but the trees require cross pollination for proper fruit set. Kary carambolas a re also sweet but better adapted to g rowing conditions in Hawaii. Arkin carambolas typically have 80% less oxalic acid than Golden Star which is a tart variety of carambola (Campbell and Koch, 1988). Arkin carambola trees can reach 7 m in height with a canopy diameter of 5 m (Knight, 2002). The lower height of the trees fits under windscreens very well. Cost of Carambola Production in Florida The cost of production for an acre of carambola estimated by IFAS ( State of Florida, 2008) was $15,838. Pick, haul, and pack was the single highest line item on the income statement at $3522 / hectare ($8700/ acre). The estimated breakeven price per pound of a 20 hectare ( 50 acre ) orchard in south Florida is $0.36. The average price per pound at seven terminal markets in the U.S. on August 30, 2008 was $2.65 (USDA, 2008). Costs will vary based on the size of each individual operation. The rule of economi c s of scale dictates that larger operations will have an advantage when purchasing supplies and therefore have a lower per unit cost. Also, keeping seasonal labor available will be easier for larger firms that have other crops throughout the year. Providing a permanent source of employment for workers will reduce the need to hire supplemental workers.

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22 Carambola Orchard Recovery Post Hurricane Andrew Tropical storms and hurricanes threaten the tropical fruit industry in Florida. When hurricane Andrew hit south Florida on August 24th, 1992, tropical fruit crops were devastated. The storm produced sustained winds up to 145 mph (230 kph) with gusts up t o 175 mph (282 kph) and 2 to 4 inches (5.08 to 10.16 cm) of rain (Hebert et al., 1992) Because the storm passed directly over Miami Dade County tropical fruit trees were subjected to the leading and tailing edges of the storm, producing winds in multiple directions. Ten to 15 months after the storm, tree survival rate was recorded by tropical fruit researchers. The findings revealed that 93% of carambola trees survived the storm. Thirteen percent of the trees were toppled, leaving 76% of the trees still s tanding, the toppled trees were stood up soon after the storm. Only grafted lime trees had a better tree survival rate. Mango, longan, and lychee had significantly higher tree dest r uction. The flexible limb structure of carambola trees attributed to their high survival rate. In many cases the windbreaks, consisting of Australian pine plantings ( Casuarina equisetifolia), fell onto the trees they were intended to protect. The windscreens, which were anchored with wooden or aluminum poles and wires holding sha de cloth, lost all of their screens and some of the structures (Crane et al., 1993 and 1994). Despite the high rate of survival for carambola trees, acreage began to decline as prices declined. Growers started replacing carambola with lychee, longan, and s ome avocado. An estimated 10% of carambola acreage was lost to development (J.H.Crane, Personal communication, July 13, 2007). Before the 1992 storm there w ere 650 acres of carambola in production in south Florida, yielding almost 40,000 lbs per acre; by 1994 there w ere 532 acres. By December 1994 production for all tropical fruits was 35% below pre hurricane Andrew production (Degner et al., 1997).

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23 Consumers and Retailers For produce buyers quality is the top concern, especially the appearance of the fruit. The primary complaint that buyers have about carambola is bruising of the ribs (b uyers are also concerned about consumer s knowledge of tropical fruits) however, carambolas are more recognized by consumers than most tropical fruits produced in Flori da. Only mangos, avocados, and papaya are more familiar to consumers than carambola Despite being better recognized than other tropical fruits, growers and retailers feel that an increased marketing effort could increase consumers awareness of the fruit. Of the retail stores surveyed by Degner (1997), 97% carried carambola while it was in season. Only mangos and papayas had higher rates of distribution, at 100%. Of the retailers who carried carambola, 47.3% indicated excellent sales, 35.6% indicated fair sales, and 17.1% indicated poor sales suggesting that most retailers believe that carambola have good sales when compared to other tropical fruits. These retailers also noted that short seasonal availability and tart fruit are problems (Degner, 1997). Tart varieties are not commonly produced commercially; instead the tart fruit probably comes from picking sweet varieties too early. The harvest seasons of carambola could be extended by manipulation of fruit set and selective pruning but this is not commonly practiced commercially. Physiology, Harvesting and Storage The physical appearance of the fruit at the retail level is a major postharvest problem. Mechanical injuries that occur during the growth, picking, or packing of the fruit cause the appearance to deteriorate and provide sites for pathogens to enter. Mechanical injuries can be caused by cuts, scrapes, impacts or vibration. The fruit can develop fin browning, wrinkled stem ends, surface browning (bruising caused by membrane disruption) and pitting, a nd water loss due to mechanical damage and low humidity storage (Kader, 2002).

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24 Fruit accumulate sugar only while on the tree, getting progressively sweeter as the color changes from green to yellow and then orange. The brix/titratable acidity ratio is sig nificantly higher at each color stage only while on the tree (Narain, 2001). The fruit in the yellow and orange stages are susceptible to damage and too fragile to pack and ship (Oslund and Davenport, 1983). Fruit also decreases in firmness postharvest. The yellow color stage is associated with changes in cell wall constituents. Cellulose accumulates while hemicellulosic materials and pectins decrease gradually beginning at the one quarter yellow stage (Mitcham and McDonald, 1991: Chin et al., 1999). Once harvested sugar concentrations remained fairly constant in low temperature storage and slightly decreased in fruit stored at 10 oC. Five degrees Celsius is the low temperature threshold for carambola. Acidity (oxalic and malic acids) slightly decreased in fruit stored at 10 oC but did not change in fruit stored at 5 oC. Fruit stored at 10 oC more likely had a higher metabolic rate (Campbell et al., 1987: Siller Cepeda et al., 2004). Likewise, weight loss and color development were slowed when stored at 5 oC as apposed to storage at 10 oC and 28 oChilling injury is a disorder that ef fects tropical and subtropical fruits when they are stored above freezing temperature but below their threshold for cold storage. While chilling injury is not common in carambola stored at 10 C. Ali et al., found that color development of carambola (cv. B 10) was closely linked to the storage temperature than to a modified atmosphere packaging (MAP) treatment (2004) oC, Ali et al. reported chilling injury in fruit held at 10 oC f or 40 days in MAP (2004) The symptoms of chilling injury are tissue browning, pitting, uneven ripening, failure to ripen, water soaking, off flavor development, and an increase of pathogens leading to decay. These symptoms generally do not appear until the fruit is removed from the low temperature and transferred to a higher temperature. The more physiologically mature a fruit

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25 is when placed into chilling temperatures the less apparent the injury. This is partly because the major changes in the fruit have already taken place and cannot be disrupted by colder temperatures (Kader, 2002). Florida carambola is currently harvested early in maturity, while the fruit is still firm, to reduce mechanical injury. The fruit is harvested by hand into plastic boxes and transported to the packinghouse. Fifty three percent of the fruit harvested is sold to a packer/shipper from the orchard, while 44% of the fruit is packed and shipped by the grower (Degner, 1997). At the packinghouse the fruit is hand sorted and placed in to cardboard boxes with a cardboard grid to separate each fruit, usually stem end down onto a foam liner. To slow desiccation, the fruit are sometimes wrapped in wax coated paper and then packed into the box. Flavor and Volatiles Carambolas have a unique aroma volatile profile contributing to a sweet floral flavor. Using a capillary gas chromatograph/mass spectrometer combination (GC/MS), 41 aroma volatiles were identified in carambola (Wilson et al., 1985). In one previous report 178 components were detec ted and identified by GC and GC MS methods in B.10 variety grown in Malaysia and exported to Europe. The main volatile components of the Malaysian fruit were esters. Interestingly carambolas were verified to share lactone constituents also found in peaches, apricots, and plums (MacLeod and Ames, 1990). More recently 53 volatile compounds were found to contribute to the unique flavor of carambola fruit using headspace solid phase micro extraction (SPME) and solvent extraction, (GC/MS), and gas chromatogra phy olfactometry (GC O). Methyl benzoate (musty minty floral sweet) and ethyl benzoate (tropical sulfur like floral) are two of the major compounds in concentration and aroma activity (Mahattanatawee et al., 2005). There are also some compounds that contri bute to an overripe or unpleasant sulfur taste such as: 1 pentanol (apricot/banana), benzothiazole (sulfur/rubber), and

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26 quinoline (putrid/fish y) (Mahattanatawee et al., 2005 ; Wilson et al., 1985). Other major constituents were esters, aldehydes, alcohols, ketones, and some norisoprenoid compounds (Mahattanatawee et al., 2005 ; Herderich et al., 1997). There are several explanations for the discrepancies in the number of volatile constituents reported in carambola. Testing methods most likely cause the major differences in the number and types of volatiles identi fied, and some research focuses only on the volatiles that are in high enough quantity for humans to perceive Varietal type is another possible reason for the differences in the volatiles reported. Al so, carambolas have probably been studied at different color stages. As indicated by Herderich et al., C13Norisoprenoid flavor precursors were identified in carambola. These compounds are by products of carotenoid degradation (1992) Carotenoids in caramb ola are produced in high amounts while the fruit are mature and in Arkin, they are produced while nearing the overripe stage (Herderich et al., 1997). One more reason for the difference in the reported volatile constituents in carambolas is the difference in storage and commercial treatments the fruit have been subjected to. Some of the volatile and flavor research has been done on fruit obtained from market places and some has been directly acquired from research stations and farms. Ethylene, a common co mmercial treatment for many fruits, and a constituent of motor exhaust has been shown to reduce significant numbers (6 of 15) of key volatiles in tomato fruit. H igh temperature water treatments and low temperature storage can have similar effects (McDonald 1996). Low temperature storage has caused tomato fruits to be perceived as being more tart in sensory analysis experiments. It has also caused the volatiles that contribute to a flavor to be suppressed (Maul et al., 2000). Since tomatoes and carambolas a re fruits that have unique aroma profiles it can be assumed that the profiles are affected by the same factors.

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27 Antioxidants and Health Effects Evaluations of 14 tropical fruits produced in Florida showed that carambola have high antioxidant activity. Hig h antioxidant activity has health benefits such as protection against cell damage (Mahattanatawee et al., 2006). The majority of the antioxidants (70%) in c arambola are present in tissues and not the juice, despite the juice constituting approximately 95% of the fresh weight of the fruit. These antioxidants exist as polyphenolic compounds (Shui and Leong, 2004). Despite the aforementioned health benefits; carambola should not be consumed by people diagnosed with kidney disease. The fruit contain oxalic acid, which has been associated with a loss in renal function. Various neurological problems can occur; even death has been reported (Moyses Neto et al, 1998). C arambolas produced in the Guangzhou region of China have been found to contain heavy metals. These fruit are distributed to various parts of China and Hong Kong. Fruit produced in Guangzhou have been found to have unacceptably high levels of zinc, nickel, and cadmium. The source of cadmium is contaminated orchard soils (Li et al., 2005; Li et al., 2007) Waxes and E dible C oatings C arambola respiration is fairly constant, less than 20 mL CO2 kg1 h1 at 20oC while at breaker (1/4 yellow) stage with a slight increase while turning from yellow to orange, likely due to senescence of the fruit. Appropriate st orage conditions can slow certain biological processes such as water loss and respiration. Water loss is a problem because it leads to a loss in saleable weight, also known as shrinkage. The surface to volume ratio of carambola is high due to its unique shape; this makes storage at high relative humidity necessary. Storing carambola at 5 oC and high relative humidity (85 95%) is an effective way to maintain fruit firmness (Ali et al., 2004). Waxes can be an effective way to prevent moisture loss. Two and 6% carnauba wax has shown promising results in preventing water loss. These wax treatments had no significant effect

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28 on total soluble solids, acidity, pH, color, flavor, or sensory texture (Miller and McDonald, 1993). Waxing is also a possible treatment for slowing respiration. Applying an edible wax coat to fruit has also been shown to limit CO2 passage from the fruit to the surrounding atmosphere. In an experiment using citrus the internal concentration of CO2Ethylene increased in waxed fruit and weight loss was r educed (Hagenmaier and Baker, 1993). Ethylene is a natural plant hormone in the form of a gas. It is associated with ripening and senescence. Cultures around the world have used the properties of ethylene to enhance fruit for centuries. The bible mentions the practice of farmers who cut the top of sycamore figs in order to speed growth and ripening. The wound would initiate an ethylene response (Amos 7:14), The Romans stored ripe apples in the same room as quince in order to hasten the ripening, a nd the Chinese would burn incense in storage rooms filled with pears to accelerate ripenin g (Reid, 2002). Ethylene is associated with two systems within plant physiology. System 1 is a constant basal rate of ethylene production where ethylene is produced in low amounts. Ethylene is also initiated by stress or injury. Exogenous ethylene applied to nonclimacteric fruit or vegetative tissue downregulates (auto inhibits) ethylene production but upregulates respiration. System 2 is associated with the ripeni ng of climacteric fruits. Ethylene is produced and an autocatalytic rise in ethylene production occurs. Exogenous application of ethylene to climacteric fruit autostimulates the climacteric rise in ethylene. During a typical climacteric fruit ripening the rise in respiration is followed by or is in unison with a rise in ethylene production (Burg and Burg, 1965). Ethylene binds to the receptor site and initiates chemical changes within the fruit including: conversion of starches to sugars, pigment production, and volatile production. For nonclimacteric fruits ethylene is commonly used commercially to enhance the external color of

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29 fruit postharvest. For example: ethylene is applied to citrus postharvest to de green the fruit by degrading chlorophyll. When et hylene is applied to citrus an increase in chlorophyllase activity can be observed. Chlorophyllase is an enzyme involved in the process of degrading chlorophyll. Also, an increase in chlorophyllide A activity was observed by Amir Shapira when ethylene was applied (1987). E thylene treatments lead to a decrease in chlorophyll A and B (Amir Shapira et al., 1987). Certain cultivar s of tangerines (calamondins and Robinson tangerines) will not degreen unless ethylene is applied. Fruit treated with ethylene and th en placed in air storage chlorophyll degradation continued for 24 h then ceased (Purvis and Barmore, 1981). Carambola exhibit nonclimacteric ripening behavior Fruit stored at 25 oC produced very l ow amounts of ethylene. Once the fruit were considered fu lly ripe they were producing more ethylene and their respiration rate was also increased but this was attributed to microbial activity and senescence of the fruit (Oslund and Davenport, 1983). Lam and Wan (1987) found that respiration was slightly suppress ed by storage at lowe r temperatures and ethylene production was undetectable at 5 oC. They also reported that green fruit had higher respiration rates than ripe r fruit; this was attributed to higher physiological activity in less mature fruit. T he fruit in Lam and Wans experiment displayed higher respiration and ethylene production toward the end of their storage time, which was also attributed to senescence (1987). Ethylene has been applied to mature green carambola to initiate color change and has been p roven as an effective ripening agent. Color was enhanced by 2 day storage at 20 oC and 100 ppm ethylene. When the fruit w ere gassed for 1 day the ripening was incomplete, when gassed for 3 days the incidence of decay was significantly increased. There was no noticeable trend in soluble solids content or titratable acidity due to ethylene treatments (Sargent and Brecht, 1990). Miller and McDonald found that exogenous ethylene increased carambola peel scald, stem end breakdown, fin browning, and

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30 enhanced mold growth (1997). There was a noticeable difference in titratable acidity and total soluble solids between mature green fruit and slightly yellow fruit. The mature green fruit had higher titratable acidity, lower pH, and lower soluble solids content. The c oncentration of ethylene used in Miller and McDonalds work was 0.1 mL L11Methylcyclopropene (1 M CP ) ; this concentration might have been too high A common goal of postharvest scientists is to maintain the quality of harvested fruits and delay senescen ce. One method of attaining this goal is to limit exposure to ethylene gas. Cyclopropenes have been proven as effective ethylene antagonists; particularly cyclopropene, 1methylcyclopropene and 3,3dimethylcyclopropene (Sisler et al., 1996a) Of these com pounds 1methylcyclopropene (1 MCP commercial name SmartFreshTM) is the most stable of the cyclopropenes and active at 1000 times lower concentration in high temperature applications. 1MCP is an effective treatment for increasing the shelf life of many commodities because of its approved commercial use and ease of application. Since 1 MCP is an ethylene antagonist the benefits of application to climacteric fruits are obvious. 1MCP has proven to be effective in delaying the ripening and senescence of cli macteric and non climacteric fruits A good example can be found in plums because there are both climacteric and non climacteric varieties. Both types of plums treated with 1 MCP at 0.25, 0.50, and 0.75 L L1 showed positive effects including delayed phy sical, chemical, and biochemical changes; firmer fruit with lower percentage weight loss and lower brix to acid ratio which indicates suppressed ripening (Martinez Romero et al., 2003). Some common benefits of 1MCP application include: maintenance of firm ness and color reduction in respiration rate and ethylene production, and limiting w eight loss (Sisler et al., 1996b). 1 MCP works by binding to a metal in the ethylene receptor and out compet e s ethylene for the receptor site. 1 MCP treatment at a concent ration of

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31 0.5 nL L1 has been shown to lengthen shelf life of bananas by 12 days held at 24 oC. T he fruit ripened normally after this period. Mature green tomatoes benefitted by delaying the rise in respiration by 8 days and the rise in et hylene by 12 days lengthening shelf life by 8 days (Sisler et al., 1996a; Sisler and Serek, 1999; Jiang et al., 2004). The effectiveness of 1MCP in maintaining firmness of fruit held at various temperatures has been demonstrated in bananas, nectarines, and plums (Jiang e t al., 2004; Bregoli et al., 2005; Martines Romero, 2003). The carambola cv Fwang Tung was harvested at 1/2 yellow color and gassed in a hermetically sealed container for 24 h at 25 oC with 1MCP concentrations of 500 nL L1 or 1 L L1. Fruit respirati on was lowered significantly and the fruit had better fruit color maintenance with 1 MCP treatments at 0.5 and 1 L L1. The fruit that w ere treated did not have a significant delay in ripening (Teixeira and Durigan, 2006). All of the above treatments use d 1MCP as a gas, which requires airtight chambers and 1 h to 1 d applications with concentrations ranging from 10 to 1000 nL L1. Technology exists for 1MCP to be applied in aqueous solutions. This technology was originally developed for preharvest appli cations to be made in the field. The benefits of an aqueous application are: no airtight chambers required and shorter application times (this would allow large quantities of a commodity to be treated over a shorter time, such as on a packing line ) A 1 m i nute aqueous application 625 ug L1 had th e same effectiveness as a 9 h gaseous application of 500 nL L1 If water loss cannot be limited by storing and transporting fruit under high humidity conditions then waxing the fruit can be beneficial. During long storage periods, especially (Choi and Huber, 2008) Aqueous applica tion of 1 MCP on tomatoes delayed softening, suppressed ethylene and respirati on climacteric peaks, and delayed the production of lycopene. It also increased polygalacturonase activity (Choi and Huber, 2008; Choi et al., 2008).

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32 periods that have been extended by the use of 1 MCP, waxing fruit has been shown to limit water loss In an experiment with avocado, Jeong et al., (2003) showed that waxing limited weight loss during storage The wax and 1MCP treated fruit had delayed peaks in respiration and ethylene production (Jeong et al., 2003). 1MCP maintains the turgidity and green color of leafy vegetables such as choy sum, and bok choy (Thomson et al., 2003). Leafy vegetables are especiall y prone to wilting because of their high surface to volume ratio. If the cold chain is disrupted, 1MCP treated vegetables maintain a better appearance than non treated vegetables. 1 MCP has also been shown to reduce leaf abscission in spearmint cuttings p roduced as fresh herbs (Thomson et al., 2003). Research Objectives The objectives of this research project were to d etermine the effect of harvest maturity on the edible quality of carambola as determined by firmness, compositional parameters, and aroma profile The second objective was t o determine the effects of storage temperature, po stharvest waxing, ethylene, and 1methylcyclopropene (1 MCP) treatments on quality and delaying ripening of carambola The last objective was to c onduct a price sensitivity analysis of the costs of proposed treatments versus current handling methods

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33 CHAPTER 3 POSTHARVEST QUALITY AS AFFECTED BY HARVE ST MATURITY, STORAGE TEMPERATURE, AND WAX COATING Introduction Carambola grows well in tropical and subtropical areas and i s a good fruit for fresh consumption. When sliced it makes an attractive garnish because of its unique transverse shape. Usually the fruits are harvested early, while in the green or one quarter yellow stage and still firm, to limit mechanical injury. Frui t accumulate sugar only while on the tree, getting progressively sweeter as the color changes from green to yellow and then orange. The soluble solids content to total titratable acidity ratio is significantly higher at each color stage only while on the t ree (Oslund and Davenport, 1983; Narain, 2001). Once harvested, sugar concentrations remain fairly constant but titratable acidity slightly decreas in certain storage temperatures (Campbell et al., 1987; Siller Cepeda et al., 2004). Carambola cv. Arkin i s popular because it is sweeter and less astringent that other varieties of carambola. Arkin also has a desirable size and shape for transportation (Crane, 2007). The surfaceto volume ratio of carambola is high because of the shape of the fins. The high surface to volume ratio of some fruits leads to increased transpirational water loss. Waxing carambola significantly lessened weight loss, and fin browning, but also led to surface pitting (Miller and McDonald, 1993). Applying an edible wax coat to citrus fruit was shown to reduce CO2 transmissivity from the fruit to the surrounding atmosphere, slowing respiration as the internal CO2 concentration increased (Hagenmaier and Baker, 1993). The objective of this experiment was to establish the optimum harvest maturity for carambola based on flavor attributes (sugar and acid composition) and to examine whether waxing would aid in extending the visual quality of the fruit during postharvest storage.

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34 Material and Methods Plant Material Commercially grown Arkin carambolas were hand harvested into plastic containers (containers held approximately 30 fruit) at one quarter yellow, half yellow and three quarter yellow color stages in Pine Island, FL, on the morning of December 7 2006. The fruits were placed into t he containers on their sides and stacked up to three layers deep. The grower was Brooks Tropicals. Harvested fruits were transported in the containers to the Postharvest Horticulture Laboratory at the University of Florida, Gainesville (approximately 418 km from Pine Island) by car the same day. The fruit were stored in the plastic containers at 10 oPreparation and Treatments C overnight. The n ext morning the carambola fruit were rinsed in 200 ppm chlorine solution and allowed to air dry on paper towels a t room temperature (approximately 22 oC ) under fans for no longer than 30 minutes. Fruit were sorted by color stage as follows; one quarter yellow, up to 25 % yellow; half yellow, 25% to 50 % yellow; three quarter yellow, 75 % or more yellow with fin marg ins (tips) remain green. Green, orange, and over ripe color stages were not used in this experiment. Fruit were dipped into a container containing a commercial food grade wax (FMC Food Tech StaFresh 819F, 50:50 v/v) solution with deionized water and al lowed to air dry on metal racks until the wax was no longer sticky, at room temperature (approximately 22 oC ). The fruit were placed on plastic trays lined with paper towels and stored in temperature controlled rooms with 80 95 % RH. Fruit were either s tored constantly at 20 oC or at 5 oC for 14 d then transferred to 20 o C, to simulate commercial storage and retail conditions.

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35 Determination of Respiration R ate and E thylene P roduction Carambola fruit (n=4) were weighed and placed individual ly in 1900 mL plastic container with lids left unsealed to maintain normal atmosphere and stored at 20 oC. P rior to daily headspace sampling the plastic lids were sealed on each of the containers for 1 h Then two, 1.0mm samples (one for CO2 and one for ethylene C2H4) were withdrawn from the headspace using a syringe inserted through a rubber septum. This was repeated daily until the fruit showed signs of decay Carbon dioxide concentration was measured using a gas chromatograph (series 580; GOW MAC, Bridgewater, N.J.) fitted with a thermal conductivity detector (TCD) and a 1219 x 3.18 mm, 80/100 mesh Porapak Q column. The carrier gas (helium) flow rate was 30 ml min1. The detector and injector were operated under ambient conditions (26 to 27 C) and the oven was at 40 C. Ethylene production rate was measured using a gas chromatograph (Tracor, series 540, Arlington, VA, USA) equipped with a photo ionization detector (PID). The column for the Tracor is stainless steel packed with alumina F1, 80/100 mesh and is 914 x 3.18 mm (length x dia.) made by Supelco. The carrier gas (helium) flow rate was 40 ml min 1. The detector and injector were operated at 100 oC and the oven was 50 oRipening and Marketability C. Appearance was subjectively rated on individual fruit each 3rd d fo r each of the following disorders: fin margin browning, stem end shriveling, surface pitting / browning, and persistent green fins based on a 4 point scale (1 = No defect, 3= The limit of acceptability, 4 = Maximum damage) (Figure 3 1) (Table 31). Fruit w ere considered unmarketable when any of the subjective categories was rated a score of 4. Fruit were considered to be in the orange stage once the fruit were one quarter orange; this is the peak ripeness (Figure 3 2 ) In this experiment, once

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36 fruit were co nsidered to be at their peak ripeness (orange stage) or unmarketable the whole fruit was stored in plastic zip top bags at 20 oCompositional Analys es C until further analysis of soluble solids content, total titratable acidity, and pH. Mean (n=10) of fruit. In this experiment, fruit was stored at 20 oC until processed. The stem end and blossom ends of the fruit were discarded leaving the edible portion, approximately 80%, of the fruit which was diced while still frozen and blended in a commercial blender (Model 908, Hamilton Beach/Proctor Silex, Washington, N.C., USA), centrifuged (Model J221, Beckman, Palo Alto, California, USA) at 15,000 rpm for 20 minutes at 5 oSoluble Solids Content (SSC) Total Titratable Acidity (TTA) and pH C then the supernatant was filtered through 8 layers of cheesecloth. To determine the soluble solids content, one to two drops of the supernatant was placed on the prism of a digital refractometer (Model 10480, Reichert Jung, Mark Abbe II Refractometer, Depew, NY) and SSC was r eported as oBrix. To determine total titratable acidity and pH 6 g of filtered supernatant was added to 50 mL of deionized H2Statistical A nalysis O, and then initial pH and titratable acidity were measured using an automated titrimiter ( Model 719S Titrino, Metrohm, Herisau, S witzerland) standardized with pH 4.00 and 7.00 buffers The endpoint was set to pH 8.2 and the base solution was 0.1 N NaOH. The total titratable acidity was calculated using the malic acid equivalent. The pH was determined from the same supernatant with a pH meter standardized with pH 4.0 and 7.0 buffers. The experiment was conducted using a randomized block design. Temperature was the blocking treatment. Statistical analysis was performed using the PC SAS software package

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37 (SAS Inst itute, 2007). All data were subjected to analysis of variance and treatment means were compared using Duncans Multiple Range Test (P<0.05). Results Respiration The control fruit had similar respiration rates to the waxed treatment. Respiration rates of th e unwaxed control carambola were approximately 20.4 mL CO2 *kg1*h1 at 20 oC and the waxed carambola were about 18.7 mL CO2 *kg1*h1Ethylene Production Since the rates were not statistically different the rates were combined (Fig. 3 3). The fruit in both treatments require d approximately 21 d to turn orange and then the fruit started to display signs of senescence and decay. Ethylene production during carambola ripening at 20 oC became evident 14 d after harvest at the one quarter yellow stage (Fig 3 4) Ethylene production was detectable once the fruit began to progress from the three quarter yellow stage to the orange stage. Ethylene production became most apparent while the fruit were progressing into the over ripe stage. The maximum recorded ethylene produced was 0.8 ul / kg1*h1Weight Loss The amount of ethylene produced by waxed fruit was similar to the control. The amount of ethylene produced by waxed fruit did not always cross the detection threshold of the GC, therefore there were missing values for some replicates and a low standard error for the treatment. No interaction of harvest maturity, waxing, and temperature existed; therefore, the data w ere combined to determine the treatment effect of waxing on weight loss during storage at the two temperatures. Waxed fruit lost less weight than the unwaxed fruit at each storage temperature. Weight loss for waxed carambola was 2.4 and 3.7% for fruit stored at 5 and 20 oC respectively, for unwaxed fr uit weight loss was 6.0 and 5.9% for fruit stored at 5 and 20 oC

PAGE 38

38 respectively (Table 3 2). The mean initial weight for all fruit used in this experiment was 182.7 g. Appearance Fruit harvested at the one quarter yellow stage, waxed, and stored at 5 oC for 2 w k never reached the orange stage (Table 3 3) Instead, those fruit turned brown and had an unmarketable appearance (Figure 3 5 ) Fruit harvested at the one quarter yellow stage, unwaxed and stored at 5 oC had a rating of 3 in each of the following categories: fin margin browning, surface scald/ pitting, and stem end shriveling once the fruit were in the orange stage. The persistent green fins were rated 1. S ince these fruit took the longest to turn orange and their appearance was poor due to stemend shriveling and finmargin browning. The ground color (color of the skin at the crux of two fins) of the waxed one quarter yellow fruit held at constantly at 20 oCompositional Analyses C, turned orange, the outer fins and stem end were persistently green until signs of senescence and decay were apparent, having a rating of 4. The pH of the fruit was lowest at the one quarter yellow stage (4.09), higher in the half yellow fruit (4.19), and highest in the three quarter yellow fruit (4.33) (Table 3 4). The sugar to acid ratio increased significantly with e ach harvest maturity. There were no differences between waxed and unwaxed fruit and there were no differences between fruit stored at 5 and 20 oC. Fruit harvested at the three quarter yellow color stage had the highest soluble solids content (7.41 oBrix); half yellow fruit was slightly lower (7.04 oBrix). Fruit harvested at the one quarter yellow stage, waxed, and stored at 5 oC never reached the orange stage, instead the fruit turned brown. Informal taste tests indicate d that the waxed fruit were in an ana erobic state, which led to the formation of off flavors and fermented aromas.

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39 Discussion Respiration and Ethylene Production The respiration rate of carambola was steady only showing a slight rise as the fruit turned from orange to over ripe (Figure 3 3). These rates ar e typical of non climacteric respiratory fruit, which is similar to the pattern r eported by Lam and Wan (1987). Some of the fruit showed signs of decay in the over ripe stage. Non climacteric fruit increase their respiration rate when attack ed by decay organisms or when exposed to exogenous ethylene. Biale and Shepherd (1941) showed that lemons increased their respiration rate immediately after being exposed to the vapors (presumably aroma volatiles and ethylene) produced by the Penicillium digitarum fungus and increased their respiration rate 3 d after being inoculated with the fungus. This increase in respiration after inoculation was part of the stress response caused by a pathogen. The ethylene production became most apparent wh en the fruit were progressing to the over ripe stage, probably due to senescence and decay (Figure 3 4). Oslund and Davenport (1987) reported that microbial activity was responsible for the increase in ethylene production in the later stages. Decay organisms caus e a stress response in fruit which leads to stress induced ethylene production which is associated with a rise in respiration rate and defense against the pathogen. Weight Loss Carambolas have a high surface to volume ratio because of their unique shape. The high surface to volume ratio leads to water loss through transpiration. Water can also be lost through the stem scar, and also through any places where the integrity of the epidermis has been compromised. High relative humidity in storage areas can limit this water loss to a degree (Ali et al., 2004). Edible waxes can create a physical barrier to retain water within the fruit. This barrier also limits respiration. Miller and McDonald (1993) found that 2 and 6 % carnauba based wax

PAGE 40

4 0 applied to carambola l imits water loss without affecting total soluble solids, titratable acidity, pH, color, flavor, or sensory texture. Toxicity was not reported. Hagenmaier and Baker (1993) also showed that waxing prevents weight loss in citrus. In this experiment the waxing treatment limited weight loss significantly (Table 3 2). Color and Flavor C olor and flavor (informal taste test) were affected by the waxing treatment in this experiment, but there were no effects on total soluble solids, titratable acidity, and pH (Tabl e 3 4). Hagenmaier and Baker (1993) showed that carnauba and other types of wax coating s limited the passage of carbon dioxide out of the fruit and increase d the intern al carbon dioxide concentration The waxing treatment in this experiment was likely too limiting and prevented gas exchange so much that the internal atmospheric composition of the fruit was anaerobic and led to the formation of off flavors (informal taste test) and a brownish appearance of internal tissue for some treated fruit. The brown internal color indicates dead tissue. The wax also limited gas diffusion in the fruit that was harvested at the 3/4 color stage so much that it slowed metabolic activity and prevented the fins from turning yellow. This parallels Hagenmaier (2001) who state d that mandarins treated with thick wax coatings had a less fresh and more fermented taste than fruit treated with thinner or more permeable wax. Appearanc e The appearance of the fruit was affected by wax treatment (Table 3 3). The fruit harvested at t he one quarter yellow stage, waxed, and stored at 5 oC had an unmarketable appearance after storage. The ir internal tissue turned brown, likely due to the lack of oxygen to the inner tissues of the fruit (Figure 3 5) Fruit waxed and held at 20 oC had a li mited metabolism due to the treatment; this prevented the outer margin of the fin from turning yellow and led to the persistent green problem. In some commercial cases an appropriate waxing treatment might be beneficial

PAGE 41

41 particularly the treatment describe d by Miller and McDonald (1993), because the fruit could potentially be subjected to lower relative humidity storage. Lower relative humidity storage conditions for carambola l e d to stem end shriveling and surface pitting. Conclusions The waxing treatment in this experiment was too limiting for necessary gas diffusion. It limited respiration so much that off flavors formed normal ripening was inhibited, and internal tissue died. Fruit harvested at the 1/4 ye llow stage, treated with wax, and stored at 5 oC showed signs of chilling injury likely because the waxing treatment prevented the fruit from ripening normally. There may be potential for some waxes on carambola, especially since weight loss was significantly reduced ; however, this treatment did not aid in maintaining the overall postharvest quality

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42 Figure 3 1. Appearance defects of Arkin carambola. Upper left: fin margin browning; Upper right: stemend shriveling; Lower left; surface pitting/ browning; Lower right; persis tent green fins.

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43 Figure 3 2. Carambola maturity stages.

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44 Table 3 1. List of carambola appearance categories and subjective rating definition (3 = the limit of acceptability, 4 = unacceptable). Appearance Categories Rating Definition 1 2 3 4 Fin Margin Browning No browning Some browning visible on fins, less than 25% Browning visible on fins, 25% to 50% Browning on majority of fins, more than 50% Stem End Shriveling No shriveling Some shriveling on stem end, less than 25% Shriveling present over most of the stem end, 25% to 50 % Shriveling present over most of the stem end, more than 50%, also brown spots visible Surface Pitting/Browning No pitting/browning Some pitting or browning visible, less than 5%, all spots smaller than 1 cm Pitting or browning present, 5% to 20%, all spots smaller than 1 cm Pitting/browning present on more than 20%, or spots larger than 1 cm Persistent Green Fins No green on fin margins Very slight green on fin margins, l ess than 0.5 cm Slight green on fin margins, From 0.5 to 1 cm Green on fin margins prominent on more than 1 cm, or at stem and blossom end s

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45 0 5 10 15 20 25 30 35 40 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 Storage Period (d) CO2 (ml-kg-1h-1) Figure 33. Combined r espiration rate s of unwaxed and waxed Arkin carambola during ripening at 20 o C harvested at 1/4 yellow stage (n=8). A, 1/4 yellow stage; B, 1/2 stage; C, 3/4 Yellow stage; D, 1/4 orange stage; E, over ripe stage (senescence and decay present). Figure 3 4. Ethylene production rates of waxed and control Arkin carambol a harvested at 1/4 yellow during ripening at 20 o C (n = 4) A B C D E 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Storage Period (d) C2H4 (ul-kg-1h-1) Waxed Control

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46 Table 3 2. Weight loss for Akin carambola after storage. Weight Loss Treatment z Weight Loss (%) 5o Unwaxed C 6.04 a Waxed 2.43 b 20o Unw axed C 5.87 a Waxed 3.65 b z Within each treatment (n = 12 fruit/treatment) values followed by different letters between ripeness stages are significantly different at the P<0.05, according to Duncans Multiple Range Test. Figure 3 5. Internal browning of Arkin carambola harvested at one quarter ye llow, waxed, and stored at 5 o C for 14 d. Left: cross section of a fruit with circles added to indicate areas of internal tissue browning, Right: cross section of a normally developed fruit with no internal tissue browning.

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47 Table 3 3. Subjective appearan ce ratings for Arkin carambola at the orange stage harvested at different maturities and stored at different temperatures (n= 4) Appearance Category Storage Temperature ( o Treatment C) Harvest Maturity Fin Margin Browning Stem End Shriveling Surface Pitting/ Browning Persistent Green Fins 5 Unwaxed 1/4 Yellow 3 3 Z 3 1 1/2 Yellow 3 3 2 1 3/4 Yellow 3 3 2 1 Waxed 1/4 Yellow Y Y Y Y 1/2 Yellow Y Y Y 3/4 Yellow Y 2 2 3 3 20 Unwaxed 1/4 Yellow 2 2 1 1 1/2 Yellow 2 2 1 1 3/4 Yell ow 2 2 1 1 Waxed 1/4 Yellow 2 2 3 4 1/2 Yellow 2 1 1 3 3/4 Yellow 2 1 1 3 ZBased on Table 3 1. 1=little or none, 2=slight, 3=moderate, 4=severe Y Fruit never reached the orange stage, instead the turned brown or showed signs of decay. Table 34. Selected compositional quality parameters for Arkin carambola harvested at three ripeness stages, analyzed at full ripe stage. Compositional Parameter (1/4 yellow) X 1/2 Yellow 3/4 Yellow SSC ( o Brix) 6.06 b Y 7.04 ab 7.41 a TTA (%) 0.28 a 0.28 a 0. 25 a pH 4.09 c 4.19 b 4.33 a SSC/TTA ratio 22.1 c 25.9 b 29.9 a XWithin each treatment row (n = 4 fruit/treatment) values followed by different letters between ripeness stages are significantly different at the P<0.05, according to Duncans Multiple Ra nge Test. YSSC = Soluble Solids Content; TTA = Total T itratable Acidity (malic acid equivalent).

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48 CH APTER 4 EFFECTS OF HARVEST M ATURITY ON THE EDIBL E QUALITY AND AROMA PROFILE OF ARKIN C ARAMBOLA Introduction Carambola accumulate sugar only while on the tree, getting progressively sweeter as the color changes from green to yellow and then orange. The sugar/ acid ratio is significantly higher at each color stage only while on the tree (Narain, 2001). The fruits in the yellow and orange stages are particul arly susceptible to damage and are considered too fragile to pack and ship (Oslund and Davenport, 1983). Carambola f ruit also soften postharvest. The color stage is associated with changes in cell wall constituents. Cellulose accumulates in the intercellul ar space while hemicellulosic materials and pectins decrease gradually beginning at the 1/4 yellow stage (Mitcham and McDonald, 1991: Chin et al., 1999). Carambolas have a unique aroma volatile profile contributing to a sweet floral flavor. Using a capill ary gas chromatograph/mass spectrometer combination (GC/MS), 41 aroma volatiles were identified in carambola (Wilson et al., 1985). For B10 carambola grown in Malaysia and exported to Europe 178 components were detected and identified by GC and GC MS met hods. The main volatile components of the Malaysian fruit were esters. More recently 53 volatile compounds were found to contribute to the unique flavor of carambola fruit using headspace solid phase micro extraction (SPME) and solvent extraction, (GC/MS), and gas chromatography olfactometry (GC O). Methyl benzoate (musty, minty, floral, and sweet) and ethyl benzoate (tropical sulfur like floral) are two of the major compounds in concentration and aroma activity (Mahattanatawee et al., 2005). There are also some compounds that contribute to an overripe or unpleasant sulfur taste such as: 1pentanol (over ripe apricot/banana), benzothiazole (sulfur/rubber), and quinoline (putrid/fishy) (Mahattanatawee et al., 2005; Wilson

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49 et al., 1985). Other major constituents were esters, aldehydes, alcohols, ketones, and some norisoprenoid compounds (Mahattanatawee et al., 2005; Herderich et al., 1997). There are a few possible explanations for the discrepancies in the number of volatile constituents reported in carambola. Testing methods most likely cause the major differences in the number and types of volatiles identified, and some research focuses on only the volatiles that are in high enough quantity for humans to perceive. Varietal type is another possible reason for t he differences in the volatiles reported. More importantly, the carambolas have probably been studied while in different ripeness stages. As indicated by Herderich et al., C13Material and Methods Norisoprenoid flavor precurso rs were identified in carambola. These compounds ar e by products of carotenoid degradation. Carotenoids in carambola are produced throughout ripening, but in large amounts while nearing the over ripe stage (Herderich et al., 1997). The objective of this experiment was to investigate the compositional param eters and volatile profile of Arkin carambola when harvested at five different harvest maturi ties, ranging from 1/4 yellow to over ripe. Plant Material Arkin Carambola were handharvested into plastic containers at 1/4 yellow, 1/ 2 yellow, 3/4 yellow, orange, and over ripe stages in Pine Island, FL The fruit were placed on their side in the container up to three layers deep. The commercial grower was Br ooks Tropicals. Harvested fruit w ere transported in plastic containers to the P ostharvest Horticulture Laboratory at the University of Florida, Gainesville by car the same day. The fruit were stored in their plastic containers at 10 oC overnight. The following day fruit were prepared for compositional analysis.

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50 Preparation for C om positional Analyses Compositional analysis for SSC, TTA, pH, and all statistical analysis were done on frozen tissue (n = 4). Fruits were prepared by cutting the stem and blossom end off and the edible portion of the fruit was stored in zip top plastic fre ezer bags at 20 oFirmness C until preparation for soluble solids content, total titratable acidity, pH, total sugars, and volatile analysis. A 10mm thick slice of fruit was taken from the equator of the fruit with a sharp, stainless steel knife, and the slice was immediately placed on a stationary steel plate. Internal firmness of the fruit was evaluated using an Instron Universal Testing Instrument (Model 4411, Canton, MA, USA) equipped with a convex tip probe (8.0 mm diameter) and 5kg load cell using a crosshead speed of 50 mm*mm1Total Sugars Content assay Maximum force thr ough 7 mm deformation of a 10mm cross section slice of fruit was recorded in Newtons (N) and there were two measurements per fruit slice, at the midpoint of the locule, avoiding seeds or points with an abundance of vascular tissue. Total soluble sugars were measured in t issue that was stored at 20 oC using the phenol sulfuric method described by Dubois el al (1956) In this experiment, the stem end and blossom end of the fruit we re discarded leaving the middle 80% of the fruit, which was diced and blended in a commercial blender (Model 908, Hamilton Beach/Proctor Silex, Washington, N.C., USA), centrifuged (Model J2 21, Beckman, Palo Alto, California, USA) at 15,000 rpm for 20 minutes at 5 oC then the supernatant was filtered through eight layers of cheesecloth. Fifteen uL of the supernatant was diluted into 10 mL of cold 80% ethanol and stored at 5o To prepare samples for measurement of total soluble sugars, in a test tube: 0.5 mL of 5% phenol (w/w) was added to 0.5 mL of the sampled mentioned above, the mixture was vortexed C overnight to precipitate ethanol insoluble materials.

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51 (Model 128101, Mini Vortexer, Fisher Scientific, Pittsburgh, PA, USA), then 2.5 mL concentrated sulfur ic acid was added and the mixture vortexed again. The test tubes were let to stand for 15 min until the mixture was at or near room temperature. 100 uL of each mixture was pipetted into a well on a 96well plate. The total soluble sugars were measured by r eading the absorbance at 490 nm using a universal microplate reader (Model EL 800, BioTek Instruments Inc., Winooski, VT, USA) the absorbance values were compared to a standard curve of glucose solutions at concentrations of: 40, 80, 120, 160, and 200 ug L1Volatiles The absorbance of the standards was graphed in Excel (Microsoft Corporation, 2003) and a linear trend line was drawn. The absorbance values for the samples were put into the equation for the trend line and a value was given. Frozen fruit wa s diced and then blended in a commercial blender (Model 908, Hamilton Beach/Proctor Silex, Washington, N.C., USA). An equal weight of blended fruit and saturated NaCl solution (30% NaCl w/w) were homogenized using a polytron (Model FGLH, PowerGen 700, Fisher Scientific, Pittsburgh, PA, USA) on the highest setting. A 5 g aliquot of the homogenate was placed into a 10 mL glass vile, which was capped with a silicone septa cap, frozen and stored at 80 oC The samples were transported on dry ice to the U.S.D.A. Citrus and Subtropical Products Laboratory in Winter Haven, FL. Ten uL of 3hexanone was added to the sample to total 100 ppm as an internal standard, as well as an injection of d6phenol to total 1 ppm. The samples were stored at 80 oThe samples were analyzed following the methods of Mahattanatawee et al., 2005. The vial was placed in a water bath of 40 C for later analysi s. oC for 15 min, then a SPME fiber (50/30 um DVB/Carboxen/PDMS on a 2cm StableFlex fiber, (Supelco, Bellefonte, Pa.)) was inserted into the headspace of the sample vial and exposed for 45 min. T he f iber was then thermally desorbed

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52 in the GC injector port for 5 min at 250 oC Separation and identification of a roma volatiles was accomplished using an Agilent 6890 GC equipped with a 30 m x 0.25mm x 0.25 um HP 5 column, and coupled with a 5973N MS detector (Agilent, Palo Alto, Calif.). The column oven was programmed to maintain 50 oC for 5 min, and then increase d 4 oC /min until reaching 250 oC and then holding for 15 min. Helium was the carrier at a flow rate of 2 mL*min1. Injector and ionizing source were maintained at 250 oC and 280 o C respectively. The split rati o was 1:1 with a 0.2 uL sample injection. The splitless mode was used when samples were introduced by SPME. Data were collected using the ChemStation G1701 AA data system (Hewlett Packard, Palo Alto, Calif., USA). The peak areas were matched within treatments using the retention times, then averaged and reported as tentative identifications based on the Kovats index, which was calculated from GC/MS runs devoted to Kovats runs. The relative area for each volatile was calculated by dividing the absolute value of the peak area of the volatile sample by the area of the D6 phenol internal standard within the sample. The relative area percentage was used to calculate the concentration of the volatile within the headspace of the vial. This percentage was converted to concentration by multiplying the percentage by 1 ppm to give the value in ppb. Total volatiles were calculated by adding th e relative concentrations of volatiles reported, minus the concentrations of 3pentanone and D6phenol. This experiment revealed 27 volatiles. Mahattanatawee et al., (2005) showed 53 volatiles, and there were 41 and 178 volatiles found in Wilson et al. (19 85) and MacLeod and Ames (1990), respectively. The difference in the number of volatiles was likely due to the method of quantifying the volatiles for this experiment. If all four samples in a particular harvest maturity did not show the presence of a cert ain volatile then that volatile was not placed on the list.

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53 Results Firmness The firmness of carambola decreased with each ripeness stage (Fig. 4 1). The firmness of carambola fruit ranged from 30.5 N at the 1/4 yellow stage to 14.0 N at the over ripe st age. Fruit at the 1/2 yellow stage was 16.0 N, which was 14.8 % lower than firmness at the 1/4 yellow stage. The firmness of the fruit in the 3/4 yellow stage was 20.1 N, which was 34.1 % lower than fruit at the 1/4 yellow stage. Fruit firmness also decrea sed significantly in the orange stage (15.8 N). Compositional Parameters To test whether harvest maturity affects the flavor of Arkin carambola, the values of soluble solids content (SSC), total titratable acidity (TTA) and pH were measured in fruit har vested at five stages of maturity (Table 4 1). SSC of fruit in the 1/2 yellow stage was significantly higher than fruit at the 1/4 yellow stage (1/4 yellow). SSC of Arkin carambola ranged from 5.8 to 7.2 oThe pH of Arkin carambola ranged from 3.8 (1/4 yellow) to 4.2 (over ripe). The fruit had a different pH depending on the harvest maturity. Sugar to acid ratio is an important indica tor of sweetness. This ratio was influenced by the harvest maturity. The ratio ranged from 15.9 to 41.4. The fruit with the lowest ratio was the 1/4 yellow, while the over ripe fruit had the highest ratio but flavor was poor due to off aromas. Brix. Fruit in the orange stage was significantly higher than fruit in the 1/2 yellow stage. Total titratable acidity (TTA) of Arkin carambola ranged from 0.174 to 0.365. Fruit had different TTA depending on the maturity at harvesting. Fruit harvested in the 1/4 yellow stage had the highest TTA (0.365) and fruit harvested at the over ripe stage had the lowest TTA (0.174).

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54 Total Sugar s The total sugars in Arkin carambola ranged from 3.33 (1/4 yellow) to 4.50 (over ripe) (Table 4 2). Total sugars significantly increased by each ripeness stage, except between 1/4 orange and over ripe. Volatiles Twenty seven volatiles were present in most of the samples analyzed. Two internal standards were added for quantification purposes (Table 43). There were many more volatiles identified in some of the fruit sampled, but these were not included because they were not found in the majority of the fruit. All of the values represent the averages of four replicates; each replicate was tissue from one individual fruit. Acetic acid was the only volatile acid commonly found in the fruit samples. It was found in all of the fruit harvested in the over rip e stage. The descriptors for acetic acid are pungent stinging and sour. Ethanol was the only alcohol to be found exclusively in the over ripe fruit, which indicates anaerobic respiration and confirms that fruits that are completely orange are over ripe. 1pentanol was detected only in fruit harvested at the 1/2 yellow color stage. Mahattanatawee et al. (2005) reported that 1 pentanol has an unpleasant sulfur aroma. 1 octanol and 1nonanol were found in all samples of each of the harvest maturities. The de scriptors for 1 octanol are: soapy, chemical, metal and burnt. The descriptors for 1 nonanol are oily, floral, and powerful. There were several aldehydes that were present in greater abundance in the earlier harvested fruit. Pentanal had a concentration of 401 ppb in fruit from the 1/4 yellow stage, but the concentration drops to 99 ppb in the 1/2 yellow fruit, then 71 ppb (3/4 yellow), 54 ppb (1/4 orange), and not detected in the over ripe stage. Hexanal and 2 hexenal follow a similar trend. Furfural is o nly identified in the 1/4 yellow and 1/2 yellow fruit. Nonanal is the only aldehyde

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55 that does not follow the trend of the others; it has a concentration at least 16 times higher in the over ripe stage than any other stage. Aromatic benzene derivatives wer e also not mentioned in the literature as being important aroma contributors to carambola. Benzenecarboxylic acid, which falls into the two classes of acids and aromatic benzene derivatives, follows the same trend as acetic acid. Benzenecarboxylic acid onl y appeared in the fruit harvested in the over ripe stage. Ethyl butyrate was only found in the over ripe fruit. Ethyl ether was found in fruit harvested at all maturities. Ether analogs with sulfur are very strong compounds that give the aroma of: sulfur, mold, cabbage, and gasoline (Rouseff, 2008; Acree, 2008). Dimethyl sulfide, an ether analog with sulfur, was found in all stages except the 1/4 yellow and over ripe. Generally the ketones were less abundant in the fruit harvested at the later color stages Megastigma 4,6(E)(8) Z triene was only present in the orange and over ripe stages. Beta ionone was not present in the 1/4 yellow stage or the 3/4 yellow stages. D iscussion Firmness The firmness of the fruit decreased significantly with ripening except f or the change from 1/4 orange to over ripe (Figure 4 1). Informal tasting indicated that the texture of the fruits becomes less crisp and more watery with every progression. The data from this experiment confirms results of Mitcham and McDonald (1991) that showed a decrease firmness of carambola fruit in progressing maturities. They also reported that firmness decreased postharvest as the fruit were ripening. The decrease in firmness is reportedly due to changes in the cell wall composition. As cellulose increases, hemicellulose and pectins decrease (Chin et al., 1999). Oslund and Davenport (1983) reported that the fruit in the yellow stage are too fragile to withstand the stresses of harvest, packing, and shipping. Fruits are handled and moved several

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56 times; first they are harvested into containers in the field, and then they are transported to a packinghouse where they are sorted and hand packed into cardboard boxes for shipping. Compositional Analysis Carambola fruits increase sugar only while they are on the tree. The total soluble solids of the fruit increased during ripening on the tree (Table 4 1). The fruits in the 1/2 yellow stage had significantly higher total soluble solids content than the fruit in the 1/4 yellow stage. This parallels the statem ent made by Narain (2001) that sugar to acid ratio increases with each color stage (oTotal Sugars brix to titratable acidity ratio ranged from 6.13 to 30.05). The pH increased slightly and the TTA decreased significantly with ripening The total titratable acidity decr eased significantly while pH slightly increased in fruit that were harvested at the earlier stages and stored (Campbell et al., 1987: Siller Cepeda et al., 2004). It may be possible that as the fruit accumulate sugar on the tree they also accumulate w ater, which in turn dilutes the acid. The sugar to acid ratio is significantly higher at each stage, indicating that the fruit have a sweeter flavor when left on the tree past the 1/4 yellow stage. The total sugars assay is a more accurate measure ment of the sugars within the fruit tissue than soluble solids content. By diluting in cold ethanol, the larger pectins are removed from solution leaving sugars and some smaller pectins. The sugar value reported by the U.S.D.A. is 3.98 g of sugar per 100 g of carambola (U.S.D.A., 2008). The data from this experiment suggests that the fruit material used by the U.S.D.A was harvested in the 1/4 orange to over ripe stage, or fruit from another cultivar was used. In a commercial setting it would be impracticabl e to harvest fruit from the 1/4 orange or over ripe stages. Th ese data, as well as the data from the compositional analysis, indicates that carambola are more pleasant to eat when harvested in the 1/2 yellow color stage than the 1/4 yellow color

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57 stage (Table 4 2) because of the higher sugar to acid ratio Harvesting at a later color stage may pose some problems such as: reduced yield due to fewer harvests, a decrease in the visual quality due to increased time on the tree and susceptibility to wind scarrin g, and a shorter shelf life because the fruit are closer to the 1/4 orange stage when they are harvested. Volatiles Alkanes were not mentioned as being an important aroma class in carambola; however, they do follow a similar trend to the aldehydes by decr easing in concentration as the maturity stage progresses. Even though the alkanes are not reported as an important class of contributing compounds to the aroma volatile profile of carambola they may indicate the by products of certain physiological process es and be indicators of flavor (Table 43). Esters are an important aroma class contributing to the unique profile of carambola (Mahattanatawee et al., 2005). The two esters that were found in the samples slightly increased in concentration as the fruit progressed from the first maturity to the last. Ketones are an important class of volatiles contributing to the profile of carambola (Mahattanatawee et al., 2005; Herderich et al., 1997). The ketones generally decreased in concentration from the first matur ity to the last. Norisoprenoids are associated with carotene break down. Their presence indicated that the fruit were beginning to senesce (Herderich et al., 1997). Even though the norisoprenoids do not have unpleasant aromas themselves, their presence in dicated the formation of off aromas. Conclusions Arkin carambola had a higher sugar to acid ratio when harvested in the 1/2 yellow color stage than when harvested in the 1/4 yellow stage. Arkin carambola is popular because of its sweetness and should be harvested later than the 1/4 yellow stage to exploit its natural sweetness. The firmness data showed a decrease from the 1/4 yellow stage to the 1/2 yellow stage, but there

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58 may be postharvest treatments that will maintain firmness. The fruit that w ere harvested when completely orange w ere attractive; however, these fruit had high amounts of ethanol and other volatiles that indicate an over ripe flavor. Therefore, fruit should be consumed once they start to show some orange color and before they reach the completely orange stage.

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59 Figure 4 1. Firmness (maximum force through 7 mm of 10 mm fruit cross section) of Arkin carambola harvested at five maturities (n = 6). Table 4 1. Initial compositional parameters of Arkin carambola harve sted at five maturities. Harvest Maturity Compositional Parameter 1/4 Yellow 1/2 Yellow 3/4 Yellow 1/4 Orange Over ripe SSC 5.8 c Z 6.2 b Y 6.5 ab 7.2 a 7.2 a TTA 0.365 a 0.305 b 0.272 c 0.202 d 0.174 e pH 3.8 b 3.9 ab 3.9 ab 3.9 ab 4.2 ab SS C/TTA ratio 15.9 e 20.3 d 23.9 c 35.6 b 41.4 a Z SSC = Soluble Solids Content; TTA = Total Titratable Acidity (malic acid equivalent). YTable 4 2. Total sugars of Arkin carambola harvested at three maturities. Mean (n=4) rows with different letters are significantly different at P< 0.05, according to Duncans Multiple Range Test. Harvest Maturity 1/4 Yellow 1/2 Yellow 3/4 Yellow 1/4 Orange Over ripe Total Sugars (%) 3.33 d 3.57 c Z 3.81 b 4.36 a 4.50 a Z 0 5 10 15 20 25 30 35 1/4 Yellow 1/2 Yellow 3/4 Yellow 1/4 Orange Over Ripe Harvest Maturity Bioyield (N) Mean (n=4) rows with different letters are significantly different at P< 0.05, according to Duncans Multiple Range Test.

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60 Table 4 3. Volatile profiles of Arkin carambola harvested at five maturities. Harvest Maturity Volatile RIZ Aroma Descriptors (Rouseff) Y Aroma Descri ptors (Acree) Yellow Yellow Yellow Orange Over ripe Acids Acetic acid 595 pungent, stinging, sour sour n.d. n.d. X n.d. n.d. 14.9 Alcohols Ethanol 491 sweet n.d. n.d. n.d. n.d. 6.6 1 Pentanol 763 green, grassy, po werful fruit n.d. 5.9 n.d. n.d. n.d. 1 Octanol 1071 soapy chemical, metal, burnt 25.4 21.9 19.5 30.3 18.3 1 Nonanol 1167 oily, floral, powerful 27.5 34.4 26.3 31.3 29.1 Aldehydes Pentanal 687 almond, malt, pungent 40.1 9.9 7.1 5.4 n.d. Hexanal 801 fatty, green, grassy, powerful grass, tallow, fat 48.7 11.6 14.2 18.7 8.5 Nonanal 1108 piney, floral, citrus fat, citrus, green 40.8 20.6 21.0 68.2 1108.2 2 Hexenal 860 green, banana like fat, rancid 398.9 111.4 192.0 207.9 41 .0 Furfural 838 pungent, sweet, bread like bread, almond, sweet 83.3 6.8 n.d. n.d. n.d. Alkanes Nonane 906 alkane 50.9 n.d. n.d. n.d. n.d. Decane 1006 alkane n.d. 13.0 4.3 n.d. n.d. Undecane 1101 alkane 52.1 13.6 6.2 n.d. n.d. Dodecane 1196 alkane 34.5 12.0 7.5 4.6 5.8 Tridecane 1292 alkane 22.1 6.3 n.d. n.d. n.d. Tetradecane 1393 alkane 16.8 4.6 n.d. n.d. n.d. Aromatic Benzene Derivatives Benzenecarboxylic acid 1150 n.d. n.d. n.d. n.d. 6. 8 D6 Phenol 978 W phenol 100.0 100.0 100.0 100.0 100.0 Benzaldehyde 981 cherry, candy almond, burnt sugar 11.5 6.5 n.d. 5.9 n.d. Esters Ethyl butyrate 797 apple n.d. n.d. n.d. n.d. 48.0 Ethyl ether 516 7.1 12.5 14.6 9.1 19.9 Ether Analogs with Sulfur Dimethyl sulfide 529 sulful, moldy, cabbage like cabbage, sulfur, gasoline n.d. 3.6 4.8 4.7 n.d.

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61 Table 4 3 Continued Harvest Maturity Aroma Descriptors (Rouseff) Aroma Descriptors (A cree) Yellow Yellow Yellow Orange Over ripe Ketones Acetone 510 light, ethereal, nauseating 6.0 n.d. 2.7 n.d. n.d. 3 Pentanone 684 W ether, fruit 40.1 22.4 22.5 17.3 14.9 2 Methyl 3 Pentanone 745 8.9 4.7 4.5 n.d. n.d. 4 Hexen 3 one 837 83.3 6.8 n.d. n.d. n.d. 4 Heptanone 877 122.4 67.6 60.8 50.3 41.0 Norisoprenoids Megastigma 4,6(E) 1370 n.d. n.d. n.d. 20.7 31.1 (8)Z triene Beta Ionone 1498 dried fruit, woody, violet lik e seaweed, violet, flower, raspberry n.d. 40.9 n.d. 28.2 12.2 Total Acids 0.0 0.0 0.0 0.0 14.9 Total Alcohols 52.9 62.2 45.8 61.6 54.0 Total Aldehydes 611.8 160.3 234.3 300.2 1157.7 Total Alkanes 176.8 47.5 18.0 4.6 5.8 Total Aromatic Ben zene Derivatives 11.5 6.5 0.0 5.9 6.8 Total Esters 7.1 12.5 14.6 9.1 67.9 Total Ether Analogs with Sulfur 0.0 3.6 4.8 4.7 0.0 Total Ketones 260.7 101.5 90.5 67.6 55.9 Total Norisoprenoids 0.0 40.9 0.0 48.9 43.3 Total V olatiles 1220.3 536.7 508.0 602.7 1506.4 ZWithin each treatment (n = 1 fruit/rep, 3 reps averaged), value represents area of curve as a percentage of the area of the i nternal standard (D6 phenol). YConcentration (ppb) based on headspace of 10ml via l containing 5 g of homogenate. XListed volatiles are significant contributors to the aroma profile of carambola found in initial samples. Volatiles have been tentatively identified using Kovats Retention Index (RI). WInternal standard added to tentativel y quantify peak areas. Only D6 phenol was used in calculating relative areas. V n.d. = not detected in all replicates of the same treatment.

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62 CHAPTER 5 EFFECT OF POSTHARVES T EXOGENOUES ETHYLEN E ON THE EDIBLE QUALITIES AND AROMA PROFILE OF ARKIN CARAMBOLA Introduction Carambola displays a respiration pattern and ethylene production rates of a typical nonclimacteric fruit (Chapter 3). System 1 ethylene production is a basal rate of ethylene production. Ethylene production is also initiated by stress or in jury. Ethylene is produced in low amounts (less than 1.0 ul*kg1h1). Exogenous ethylene applied to nonclimacteric fruit or vegetative tissue downregulates (auto inhibits) ethylene production but upregulates respiration (Burg and Burg, 1965). It also initiates chlorophyll degradation by chlorophyllase activity. Chlorophyllase is an enzyme involved in the process of degrading chlorophyll. Exogenous ethylene treatments lead to a decrease in chlorophyll a and b in nonclimacteric fruit (Amir Shapira et al., 1987). For citrus, a nonclimacteric fruit, ethylene is used commercially to enhance the external color of fruit postharvest. Ethylene stimulates chlorophyll degradation and causes degreening. Sargent and Brecht (1990) showed that color of carambola was enhanced in light green fruits by 2 d storage at 20 oThe objecti ve of this experiment was to evaluate the effect of three different concentrations of ethylene treatment on the postharvest quality of Arkin carambola harvested at 1/4, 1/2, and 3/4 yellow stages. C and 100 ppm ethylene. When the fruit at light green stage was gassed for 1 d the degreening was incomplete, and when gassed for 3 d the incidence of decay was significantly increased. There was no notic eable effect on soluble solids content or titratable acidity due to ethylene treatments (1990). Miller and McDonald found that exogenous ethylene increased carambola peel scald, stem end breakdown, fin browning, and enhanced mold growth (1997).

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63 M aterial and Methods Plant Material Arkin carambola w ere hand harvested into plastic containers at 1/4 yellow, 1/2 yellow, and 3/4 yellow color stages in Pine Island, FL on the morning of August 6th, 2007. The fruit were placed on their side in the container up to three layers deep. The commercial grower was Brooks Tropicals. Harvested fruits were transported in their plastic containers to the Postharvest Horticulture Laboratory at the University of Florida, Gainesville by car the same day. The fruit were stored in their plastic containers at 10 oEthyl ene Treatment and Storage Regime C overnight. Washing, respiration, ethylene measurements, and compositional analysis for SSC, TTA, pH, and appeara nce, and all statistical analyses were done as described in C hapter 3. Volatile analysis was done according to the methods described in chapter 4. Carambola fruit were stored in 175L sealed containers on plastic trays lined with paper towels with flow through air containing 25, 50, or 100 ppm ethylene for 48 h at 20 oC 90% RH (n=4). The mixed gasses were humidified by bubbling through a jar with water in it before entering the chamber. The fruit were treated at 20 oC for 2 d, then transferred to 5 oC for 14 d (the low temperature limit) and then transferred to 20 oDays to Orange C and held until each fruit reached the orange stage (peak ripeness). Ripening of carambola was determined objectively using a handheld colorimeter (CR 400 Chroma Meter, Konica Minolta Sensing, Inc., Japan) One quarter orange stage (peak ripeness) was determined by having a positive a va lue. The fruit were subjectively rated using Table 3 1 outlined in chapter 3.

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64 Firmness In this experiment, a 10 mm thick slice of fruit was taken from the equator of the fruit with a sharp, stainless steel knife, and immediately placed on a stationary s teel plate. Internal firmness of the fruit was evaluated using an Instron Universal Testing Instrument (Model 4411, Canton, MA, USA) equipped with a convex tip probe (3.3 mm diameter) and 5kg load cell using a crosshead speed of 50 mm*mm1Volatiles Maximum force at 7 mm deformation was recorded in Newtons (N) and there were 2 measurements per fruit slice, at the midpoint of the fin, avoiding seeds. Volatiles were analyzed according to the methods described in Chapter 4. Results Days to Orange Stage Tim e required for fruit to reach the orange stage ranged from an average of 10.9 days (3/4 yellow fruit) to 20.8 days (1/4 yellow fruit) (Table 51). The fruit harvested at 3/4 yellow required the least amount of time to reach the orange stage (12.5), regardl ess of ethylene concentration treatment. The fruit harvested at the 1/4 and 1/2 yellow stages took approximately the same amount of time to reach the orange stage (20.1). Appearance Fruit treated with 100 ppm ethylene generally had more ratings of damage than those of fruit treated with 50 or 25 ppm ethylene for stem end shriveling and fin margin browning regardless of harvest stage (Table 5 2). The appearance of the fruit treated with 100 ppm ethylene for 48 h at 20 oC was poor; fin margin browning was e xacerbated by the treatment. The 100 ppm treatment had a degreening effect but did not enhance the overall appearance. Surface pitting/ browning was not affected by ethylene concentration. The ethylene treatments in this

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65 experiment did not induce the appea rance of fruit harvested at different maturities to develop more uniform color. Weight L oss Fruit harvested at the 1/4 yellow stage lost the most weight (average 3.7%), followed by fruit harvested at 1/2 yellow (average 2.6 %), and 3/4 yellow (average 1.0%) (Table 5 3). Weight loss was not affected by the concentration of ethylene Firmness There were no clear trends in the firmness data that showed effects from harvest maturity, waxing, or storage temperature ( data not shown). The probe and probing loc ation were not suitable to accurately gauge the firmness of the fruit. The probe was a 3.3 mm convex tip and the testing location was between vascular areas, which led to all fruits giving readings of the same firmness. In the next chapter a larger probe tip (8.0 mm) was used and the testing location moved to the middle of the cross section of the fin. Compositional A nalysis The soluble solids content (SSC) of fruit at the 1/2 yellow stage was slightly higher than fruit in the 1/4 yellow stage (1/4 yellow ) (Table 5 4). SSC of Arkin carambola ranged from 6.2 to 8.0 oTotal titratable acidity (TTA) of Arkin carambola ranged from 0.23 to 0.26. TTA of the fruit was not affected by ethylene or harvest maturity. The pH of Arkin carambola ranged from 4.17 (quarter yellow) to 4.35 (3/4 yellow). The fruit had a slightly different pH depending on the harve st maturity. The sugar to acid ratio was influenced by the harvest maturity but not the ethylene treatment concentration. The ratio ranged from 24.3 to 34.0. The fruit with the lowest ratio was the quarter yellow; the 3/4 ripe fruit had the highest ratio. Brix. Fruit in the 3/4 yellow stage was significantly higher than fruit in the 1/4 yellow stage. SSC of t he fruit was not affected by ethylene concentration.

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66 Volatiles Acetic acid was found only in fruit harvested at the quarter yellow stage (Table 5 5). The flavor descriptors for acetic acid are: pungent, stinging, and sour (Acree, 2008; Rouseff, 2008). Ethanol was mostly found in fruit harvested at the quart er yellow stage, but there was a small amount found in fruit harvested at 1/2 yellow and treated with 25 ppm ethylene. Mahattanatawee et al. found that aldehydes are an important class of aroma volatiles for carambola (2005). Pentanal, hexanal, nonanal, a nd 2hexenal were found in all of the samples in this experiment. Nonanal was found in great abundance in the all of the fruit, but higher in fruit treated with 100 ppm ethylene in both harvest maturities. The aroma descriptors for nonanal are: piney, flor al, citrus, fat, and green (Acree, 2008; Rouseff, 2008). The aromatic benzene derivative, benzaldehyde, was only found in fruit harvested at the quarter yellow stage treated with 50 or 100 ppm ethylene. The aroma descriptors for benzaldehyde are: cherry, candy, almond, and burnt sugar (Acree, 2008; Rouseff, 2008). Esters were found to be an important class of volatiles that contribute to carambola flavor (Mahattanatawee et al., 2005; MacLeod and Ames, 1990). Ethyl butyrate was found in higher amounts in t he fruit harvested at the quarter yellow stage. Ethyl butyrate has an aroma descriptor of apple (Rouseff, 2008). Mahattanatawee found ketones to be an important contributing class of volatiles for carambola (2005). 3Pentanone was used as an internal stan dard and co eluted with peaks in the same class of volatiles naturally found in carambola. This masked the presence on the chromatogram of natural ketones that may have been present in the fruit; however, 4 heptanone was identified and found to be in highe r concentrations in fruit harvested at the 1/2 yellow color stage.

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67 Megastigma 4,6(E)(8)Z triene was found in most of the samples but were higher in the fruit harvested at 1/2 yellow stage. The norisoprenoid compounds are important because they are associated with carotene degradation and are likely associated with off flavors and aromas. Beta ionone, another norisoprenoid, was only found in fruit harvested at the 1/2 yellow stage. Beta ionone is also associated with carotene degradation. Discussion Days t o Orange The 1/4 orange stage is the peak ripeness of Arkin carambola once the fruit is completely orange the flavor is affected by off aromas In this experiment, there was no treatment effect for days to orange ; however, the fruit treated with the hig hest ethylene concentration degreened faster The harvest maturity dictated the days required for the fruit to turn orange (Table 51 ). Even though the statistics indicated little difference between harvest maturities and days to orange, there is significa nce when considering the feasibility of shipping the fruit and displaying them in a retail situation. Even though the Duncan grouping assigned similar letters to many of the averages, there are other factors affected by the time required to reach the orang e stage. More weight is lost in fruit that are stored for a longer period of time. Fruit treated with 100 ppm had a higher incidence of fin margin browning. The formation of off aromas also takes place during longer storage periods. For the next experiment days to orange will consider all of the replicate fruits within a treatment rather than each fruit. Appearance The degreening of the fruit treated with 100 ppm ethylene most likely was caused by an increase in chlorophyllase activity (Table 5 1). The eth ylene treatments led to a decrease in chlorophyll a and b. When ethylene is applied to citrus, an increase in chlorophyllase activity is observed. Chlorophyllase is an enzyme involved in the process of degrading chlorophyll, which

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68 causes to degreening. Als o, an increase in chlorophyllide a activity was observed by Amir Shapira when ethylene was applied (1987). Sargent and Brecht (1990) show ed that color was enhanced by 2 d storage at 20 oWeight Loss C and 100 ppm ethylene for fruit harvested at light green. In this ex periment, fruit appearance was negatively affected by the same treatment before storage; however, the 100 ppm ethylene treatment was the only concentration that had a degreening effect on the fruit. The appearance of the fruit was not homogeneous after bei ng treated with ethylene. Fruit harvested at the 1/4 yellow stage was still greener than fruit harvested at the 1/2 and 3/4 yellow stages. The only factor affecting weight loss was harvest maturity (Table 5 2). This was likely due to the green er fruit taking longer to reach the orange stage. The greener the fruit at harvest, the longer it took to reach the 1/4 orange stage; therefore, fruit harvested at greener stages lost the most weight during the longer storage. This trend is similar to a pr evious report that showed weight loss of carambola was increased by long term storage at 5 and 10 oCompositional Analysis C (Campbell et al., 1989). The range of SSC of the fruit in this experiment (6.23 to 8.00 oBrix) (Table 5 3) is higher than the range reported in Chapter 3 (6.06 to 7.41 oThe titratable acidity of the fruit was not affected by the ethylene treatment or the harvest maturity. This was likely due to a similar storage time for all fr uit. Campbell et al. (1987) and Siller Cepeda et al. (2004) both reported that acidity decreased with storage time. Brix) (Table 4 1). This is likely because the fruit in this experiment were grown during summer months with longer days, which allowed the fruit to accumulate more soluble solids. In contrast, the fruit used in Chapter 3 were grown during the winter and were subjected to shorter days and a lower angle of the sun.

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69 The fruit had a slightly different pH depending on the harvest maturity. Sugar to acid ratio is an important indicator of sweetness in caram bola. This ratio was influenced by the harvest maturity but not the ethylene treatment concentration. The fruit with the lowest ratio was the quarter yellow; the three quarter ripe fruit had the highest ratio. This reflects the statement made by Narain (20 01) that the sugar to acid ratio increases with each color stage. Volatiles Ethanol was mostly found in fruit harvested at the quarter yellow stage, but there was a small amount found in fruit harvested at 1/2 yellow and treated with 25 ppm ethylene. The formation of ethanol was likely due to a longer storage time. Nonanal was likely a by product of increased respiration due to the high ethylene concentration treatment. In the previous experiment (chapter 4), the samples that had an abundance of nonanal w ere in the over ripe stage. Nonanal is associated with an over ripe and off flavor. Norisoprenoids indicate the physiological changes that occur when fruit reach their peak ripeness and increase in concentration while the fruit begin to become over ripe. Norisoprenoid compounds were reported as important aroma contributors by Mahattanatawee et al. (2005) and Herderich et al.(1992). Ethyl butyrate was found in higher amounts in the fruit harvested at the 1/4 yellow stage. Ethyl butyrate has an aroma descri ptor of apple (Rouseff, 2008). The scent of the fruit in the green stage had a strong green apple aroma (Informal observation). Conclusions When exposed to 100 ppm ethylene for 48 h at 20 oC the epidermis of carambola was noticeably degreened but surface pitting/ browning of the fruit was increased. The ethylene treatment had no affect on the compositional parameters of the fruit. The ethylene treatments

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70 increased the total volatiles and more of them were associated with over ripe and off flavors. The ethyl ene treatments did not enhance ripening enough to promote a uniform color for fruits harv ested at different color stages.

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71 Table 5 1. Average days required for fruit to turn orange after harvest at three maturities, treated with ethylene and stored at 20 o Harvest Maturity C. Ethylene Concentration (ppm) Days to Orange 1/4 Yellow Z 25 20.8 0.42 a 50 20.8 0.42 ab 100 20.7 0.48 ab 1/2 Yellow 25 19.7 0.67 ab 50 19.2 0.92 abc 100 19.3 0.82 bc 3/4 Yellow 25 10.9 4.43 d 50 13.8 4.87 cd 100 12.7 5.06 d ZTable 5 2. Appearance ratings for Arkin carambola fruit treated with ethylene once reaching the orange stage. Mean (n = 10) followed by standard deviation. Different letters are significantly different at P<0.05, according to Duncans Multiple Range Test. Ethylene Concentration (ppm) Harvest Maturity Appearance Categories Fin Margin Browning Stem End Shriveling Surface Pitting/ Browning 100 1/4 Yellow 4 2 2 100 1/2Yellow 4 3 3 100 3/4 Yellow 2 2 3 50 1/4 Yellow 2 2 2 50 1/2Yellow 3 3 3 50 3/4 Yellow 2 1 3 25 1/4 Yellow 3 1 1 25 1/2Yellow 3 3 2 25 3/4 Yellow 1 1 3 Based on Table 3 1. 1=little or none, 2=slight, 3=moderate, 4=severe

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72 Table 5 3. Weight loss (expressed as % of original weight) for fruit upon re aching the orange stage. Harvest Maturity Ethylene Concentration 25 ppm 50 ppm 100 ppm 1/4 Yellow 4.0 a 3.5 a Z 3.7 a 1/2 Yellow 2.8 b 2.2 b 2.8 b 3/4 Yellow 0.7 c 1.0 c 1.4 c Z Within each treatment (n = 10 fruit/treatment) values followed by differ ent letters between ethylene concentrations are significantly different at the P<0.05, according to Duncans Multiple Range Test. Table 5 4. Selected compositional quality parameters for Arkin carambola harvested at three color stages, treate d with ethylene, and analyzed at full ripe stage Compositional Parameter 1/4 Yellow z 1/2 Yellow 3/4 Yellow SSC ( o Brix) 6.23 b y 6.82 ab 8.00 a TTA (%) 0.26 a 0.23 a 0.23 a pH 4.17 b 4.18 b 4.35 a SSC/TTA ratio 24.3 c 29.3 b 34.0 a ZWithin each row (n = 6 fruit/treatment) values followed by different letters between ripeness stages are significantly different at the P<0.05, according to Duncans Multiple Range Test. y SSC = Soluble Solids Content; TTA = Total T itratable Acidity (malic acid equivalent).

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73 Table 5 5. Headspace aroma volatiles (relative areas) for Arkin Carambola harvested at 1/4 and1/2 yellow, in relationship with ethylene treatment and harvest maturity, analyzed at fullripe stage. 1/4 yellow 1/2 Yellow Ethylene Concentrat ion (ppm) Volatile RI ZY 25 50 100 25 50 100 Acids Acetic acid 595 68.2 48.2 50.8 n.d. n.d. X n.d. Alcohols Ethanol 491 17.3 13.8 13.5 3.8 n.d. n.d. 1 Octanol 1071 9.2 7.9 9.3 11.5 11.7 11.2 1 Nonanol 1167 8 n.d. 8. 5 8.6 8 8.5 Aldehydes Pentanal 687 24.3 30 20.5 22.3 23.6 196.3 Hexanal 801 93 125.8 85.3 74.8 70.3 151.9 Nonanal 1108 1604.7 1337.5 2443.1 1058.9 1079.8 1243.9 2 Hexenal 860 15.6 15.2 21.2 35.3 21.6 21.4 Alkanes Nonane 906 7.3 14.4 10.6 n.d. n.d. n.d. Decane 1006 8.4 n.d. 12 n.d. n.d. 9.3 Dodecane 1196 n.d. n.d. n.d. n.d. n.d. 7.2 Tridecane 1292 n.d. n.d. n.d. 7.5 n.d. n.d. Tetradecane 1393 10 8.9 14.4 7.4 8.3 8.7 Aromatic Benzene Derivatives D6 Phenol 978 X 100 100 100 100 100 100 Benzaldehyde 981 n.d. 14.1 18.2 n.d. n.d. n.d. Toluene 771 12.6 n.d. 5.2 8.9 n.d. 13.2 Esters Ethyl butyrate 797 51.6 25.3 52.7 21.7 20.7 n.d. 2 Ethyl 2 Butenal 798 93 125.8 n.d. n.d. n.d. n.d. Ethyl ether 516 19.3 30.5 9.8 13.7 17.4 16.9 Ketones 3 Pentanone 684 17.9 30 18.5 22.3 21.3 17.6 4 Heptanone 877 33.7 34.8 39 48.4 43.2 37.4 Norisoprenoids Megastigma 4,6(E) 1370 14.8 n.d. 8.7 20 1 2.2 17.7 (8)Z triene Beta Ionone 1498 n.d. n.d. n.d. 9.4 11.6 9.9

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74 Table 5 5 Continued Total Acids 68.2 48.2 50.8 0.0 0.0 0.0 Total Alcohols 34.5 21.7 31.3 23.9 19.7 19.7 Total Aldehydes 1737.6 1508.5 2570.1 1191.3 1195.3 1613.5 Total Alkanes 25.7 23.3 37.0 14.9 8.3 25.2 Total Aromatic Benzene 12.6 14.1 23.4 8.9 0.0 13.2 Derivatives Total Esters 163.9 181.6 62.5 35.4 38.1 16.9 Total Ketones 33.7 34.8 39.0 48.4 43.2 37.4 Total Norisoprenoids 14.8 0.0 8.7 29.4 23.8 27.6 Total Volatiles 2091.1 1832.4 2822.8 1352.1 1328.4 1753.5 Z Total Volatiles calculated as the absolute value of the sum of all volatiles minus the areas of the internal standards; n.d. not detected, the peaks not integr ated into all reps in the sample selection. YListed volatiles are significant contributors to the aroma profile of carambola found in initial samples. Volatiles have been tentatively identified using Kovats Retention Index. XWithin each treatment (n = 3 fr uit/rep, 2 reps averaged), value represents area of curve as a percentage of the area of the internal standard (D6 phenol).

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75 CHAPTER 6 INFLUENCE OF AQUEOUS 1METHYLCYCLOPOPENE AP PLICATION TO ARKIN CARAMBOLA FRUIT FIRM NESS AND VOLATILE PR OFILE Introductio n Mechanical injury and stress caused an increase in respiration and decreased the shelf life of fruits. Mechanical injury and stress trigger an ethylene response. Stress induced e thylene production auto inhibits (downregulates) ethylene production and upregulates respiration. 1methylcyclopropene (1 MCP) is an ethylene antagonist. 1MCP works by out competing ethylene and bind ing to ethylene receptor sites. By doing this, 1MCP prevents the increase in respiration that is caused by ethylene exposure (Sis ler et al., 1996). 1MCP can maintain the firmness of climacteric and non climacteric fruits when applied postharvest (Jiang et al., 2004; Bregoli et al., 2005; Martinez Romero, 2003). A previous report showed that Fwang Tung carambola treated with a 24 h treatment of gaseous 1 MCP maintained color. The experiment also showed that 1 MCP decreased fruit respiration and but did not extend the number of days till the fruit were ripe (Teixeira and Durigan, 2006). 1MCP is also effective when used as an aqueo us dip. An aqueous application does not require as much exposure time as a gaseous application, there is also no need for an airtight container or room (Choi and Huber, 2008). Two experiments are reported in this chapter. The objective of the first experim ent was to determine the effect of a postharvest aqueous 1 MCP treatment (200 ug of 1MCP a.i. (active ingredient) L1) on selected parameters of carambola fruit quality. Based on the results of the first experiment, the objective of the second experiment was to determine the effectiveness of aqueous 1MCP treatments at lower concentrations (50, 100, and 200 ug of 1MCP a.i* L1 ).

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76 Material and Methods Plant Material Arkin carambolas were hand harvested into plastic containers at 1/4 yellow, 1/2 yello w and 3/4 yellow color stages in Pine Island, FL on the morning of February 5th, 2008 (for the first experiment) and August 28th, 2008 (for the second experiment) The fruit were placed on their side in the container up to three layers deep. The commercial grower was Brooks Tropicals (Homestead, Fla.). Harvested fruits were transported in their plastic containers by car the same day to the Postharvest Horticulture Laboratory at the University of Florida, Gainesville. The fruit were stored in the containers at 10 oTreatment with Aqueous 1MCP C overnight. The following morning, fruits were sorted based on color stage, washed and randomized into respective treatments; fruit were segregated for respiration measurements and initial firmness. Fruit were subme rged in aqueous 200 ug*L1 1methylcyclopropene (1 MCP) for 1 min. The solution was prepared from formulation AFxRD 300 (2% active ingredient, AgroFresh, Inc., Rohm and Haas, Philadelphia, PA). The solution was prepared with 200 ug of 1 MCP a.i. (active in gredient) L1 Fruits were stored on plastic trays lined with paper towels at 5 or 20 The powder was suspended in 10 L of water in a plastic bucket and stirred lightly. The solution was used within 30 min after preparation. Treated fruit were wiped dry with a paper towel and placed onto plastic trays lined with paper towels. Storage oC. Relative humidity was maintained (85% to 95% RH) by covering the fruit with thin plastic sheets. Fruit were considered to be at the peak ripeness when they were 1/4 orange (Figure 32). Orange was

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77 defined as having a positive a value on a handheld colorimeter. Once fruits were at peak ripeness stage they were subjected to destructive analyses. Quality Analyses Fruit were rated subjectively based on Table 3 1. Preparation f or compositional analysis for soluble solids content (SSC), total titratable acidity (TTA) and pH were done according to the methods described in the Material and Methods section of chapter 2. Firmness In this experiment, a 10mm thick slice of fruit wa s taken from the equator of the fruit with a sharp, stainless steel knife, and then the slice was immediately placed on a stationary steel plate. Internal firmness of the fruit was evaluated using an Instron Universal Testing Instrument (Model 4411, Canton, MA, USA) equipped with a convex tip probe (8.0 mm diameter) and 5 kg load cell using a crosshead speed of 50 mm*mm1Statistical Analyses There were two measurements per fruit slice, at the midpoint of the locule, avoiding seeds or points with an abundance of vascular tissue and maximum boiyield through 7 mm deformation of a 10mm cross section was recorded in Newtons (N). Volatile Analysis Volatiles were measured according to the methods described in C hapter 3. Statistical analyses were performed accor ding to procedures outlined in Chapter 2. Results: Experiment 1 Respiration The respiration rate of carambola harvested at the 1/4 yellow stage and stored at 20 oC was suppressed by the 1 MCP treatment for 9 days (Figure 6 1). Respiration for these frui t

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78 ranged from 20.3 to 28.2 ml CO2 kg1h1 for controls and from 15.7 to 23.9 ml CO2 kg1h1 for 1 MCP treated fruit during 9 d of storage. Respiration was not significantly suppressed by 1 MCP treatment for fruit harvested at 1/2 yellow and 3/4 yellow whe n stored at 20 oDays to Peak Ripeness and Weight Loss C for any number of days. T herefore, data w ere presented only for Day 3 of storage that shows overlapping standard error bars for fruit harvested at the 1/2 and 3/4 yellow stages (Figure 6 2). For frui ts stored at 5, 10, and 20 oC, 1MCP extended days to 1/4 orange only for fruit harvested at 1/4 yellow and 1/2 yellow. The fruit harvested at 3/4 yellow and treated with 1 MCP reached the 1/4 orange stage in the same length of time as the untreated contro ls; 9 d after transfer from 5 oC, 3 d after transfer from 10 oC, and 7 d when stored at 20 oC constantly. All fruit within a treatment were considered orange on the day when the majority of the fruit showed 1/4 orange. Weight loss ranged from 2.25 to 4.20 % of initial weight in fruits stored at 5 oC, 1.19 to 3.91 % at 10 oC, and 1.19 to 2.71 % at 20 oC (Table 6 1). For the fruit stored at 5 oC, and treated with 1 MCP had higher weight loss, while for fruits stored at 10 and 20 oAppearance Ratings C, 1MCP treated fruit had si milar weight loss to the controls. The 1MCP treated fruit had better appearance as indicated by lower incidences of fin browning, stem end shriveling, and surface pitting/ browning (Table 62). However, for treated fruit, at the 1/4 or ange stage fin margins were persistently green. Firmness Fruit treated with 1 MCP remained firmer than the controls, irrespective of harvest maturity or storage temperature (Table 6 3). Upon reaching 1/4 orange stage, fruit firmness

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79 ranged from 5.6 to 9.7 N for the untreated fruit, and from 9.1 to 16.4 N for 1MCP treated fruit. Because the analysis for firmness was done using a destructive method, the initial values were collected 1 d after harvest. Compositional Analysis T here were no treatment effects on the compositional parameters of the fruit (Table 64). The soluble solids content of the fruit ranged from 6.40 to 7.12 oBrix. The fruit harvested at the 1/4 yellow stage had the lowest soluble solids content (6.40 oBrix), the fruit harvested at 1/2 yel low and 3/4 yellow stages had higher soluble solids content (7.08 and 7.12 oVolatiles Brix respectively). The total titratable acidity (TTA) ranged from 0.271 to 0.307. Fruit harvested at the 1/4 yellow stage had the highest titratable acidity content (0.307), frui t harvested at the 1/2 yellow stage had lower total titratable acidity (0.271), the fruit harvested at the 3/4 yellow stage had a total titratable acidity of 0.229. The sugar to acid ratio ranged from 20.85 to 31.09 and increased significantly as harvest maturity increased. Initial volatiles were measured in the harvest maturity experiment of Chapter 4 (Table 4 3). For this experiment fruit were analyzed upon reaching the peak ripeness stage (1/4 orange). For the fruit stored at 5 oC, 1pentanol was found only in the control fruit harvested at 1/2 yellow (Table 6 5 ). 1 pentanol was found in all of the treated and control fruit that were stored at 20 oC. 1octanol was found in all of the samples except the fruit treated with 1 MCP and stored at 20 oC. Beta ionone was the only norisoprenoid compound found in the samples from this experiment and was only found in fruit that were stored at 20 oThe fruit harvested at 1/4 yellow, treated with 1 MCP, and stored at 5 C. oC had an abnormally high am ount of nonanal (623% higher than the next highest amount reported). Data showed that 1 MCP treatment suppressed total volatiles for fruit harvested at 1/2 yellow and

PAGE 80

80 stored at 5 oC by 40%. The data also show ed that 1 MCP suppressed total volatiles produce d by all fruit stored at 20 oC, for fruit harvested at the 1/2 yellow stage total volatiles were suppressed by 28%. Apart from the outlier of the 1/4 yellow fruit treated with 1MCP and stored at 5 oC, there is a clear trend that 1 MCP suppressed total vol atile production, regardless of harvest maturity or temperature. Excluding the outlier of nonanal, the fruit stored at 20 oC had higher total volatiles than the fruit stored at 5 oC. Fruit harvested at 1/2 yellow, not treated, and stored at 5 oC had volati le production suppressed by 42% compared to fruit harvested at the same color stage and stored at 20 oDiscussion: Experiment 1 C. Respiration Respiration was suppressed by the 1MCP treatment (Figures 6 1and 62). The respiration rate of the fruit harvest ed at the 1/4 yellow stage was reduced by 15 to 23%. This was more than the fruit harvested at the 1/2 yellow and 3/4 yellow stages, which did not show significant reductions in respiration from the 1MCP treatment. These results are in agreement with the experiments with 1 MCP and carambola fruit by Teixeira and Durigan (2006) with Fwang Tung treated with gaseous 1MCP. Days to Peak Ripeness and Weight Loss Weight loss was not directly affected by the 1 MCP treatment but fruit treated with 1 MCP lost more weight that the untreated controls (Table 61). This was due to the fruit requiring more time to reach the 1/4 orange stage. The longer the storage time more weight was lost by the fruit. Wills and Ku (2002) reported that 1MCP delayed ripening and inc reased shelf life of tomatoes and that weight loss was not affected T he results of Teixeira and Durigan (2006), showed that 1MCP did not significantly delay ripening in fruit harvested at the 1/2 yellow stage.

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81 Appearance Ratings The 1 MCP helped to maintain the chlorophyll in the present experiment in the fruit that were treated had a greener appearance and persistently green fins. Persistently green fins were more evident in fruit that were harvested at 1/4 yellow.1MCP decreased the activity of chlorophyllase and peroxidase, causing green color maintenance of broccoli florets (Gong and Mattheis, 2003). Color maintenance was also reported in avocado epidermis (Choi et al., 2008), tomatoes (Choi and Huber, 2008 Wills and Ku, 2002), and Fwang Tung carambola (Teixeira and Durigan, 2006). Firmness The firmness of carambola was significantly maintained by the 1 MCP treatment (Table 6 2). The initial firmness of the fruit decreased with the harvest maturity as also reported by Chin et al. (1999) for carambola fruit, due to changes in cell wall composition as the hemicellulose and pectins decreases and cellulose increases. These results confirm the results reported previously that 1MCP can maintain the firmness of climacteric and non climacteric fruits when ap plied postharvest (Jiang et al., 2004; Bregoli et al., 2005; Martinez Romero, 2003). Compositional Analysis C ompositional parameters tested were not significantly affected by 1 MCP treatment (Table 6 3). The firmness and sugar to acid results indicate tha t if fruit were harvested in the 1/2 yellow color stage and treated with 1 MCP then the fruit would taste significantly sweeter and have a crisper texture. Volatiles Ripening carambola at 20 oC did not hinder synthesis or aroma volatiles. To isolate the e ffect of 1 MCP on the volatile profile of carambola, the best example is the fruit held at 20 oC (Table 6 5). Total volatiles were suppressed by the 1 MCP treatment. This parallels data reported

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82 by Porat et al. (1999), who also reported an increase in off flavor formation. Total volatiles were suppressed by the 1MCP treatment because the 1 MCP slowed physiological functions, such as color development, which produce volatiles. Results: Experiment 2 Based on the results from the first experiment using 1MC P, a second experiment was designed to examine the effects of 1 MCP at a lower range of concentrations. 1 MCP treatment at 200 ug of 1 MCP a.i .*L1 maintained firmness, but suppressed volatile production and caused the fruit to keep the green appearance of their fins. Aqueous solutions of 1MCP were prepared as above at concentrations of 50, 100, and 200 ug of 1MCP a.i .*L1Respiration The respiration rates of 1 MCP treated fruit were similar to controls (Figure 6 3). Respiration was not significantly suppressed by 1 MCP treatment for fruit harvested at 1/2 yellow and 3/4 yellow when stored at 20 oC. Respiration of fruit harvested at the 1/2 yellow stage ranged from 20.79 to 31.50 ml CO2 kg1h1Days to Peak Ripeness an d Weight Loss for fruit during 6 d of storage. For fruit harvested at 1/4 yellow and 1/2 yellow, treated with the highest concentration of 1MCP (200 ug*L1), the time at 5 oC days required to reach 1/4 orange were extended by 2 d. Fruit harvested at 3/4 yellow and treated with 1 MCP took the same amount of time to reach the 1/4 orange stage as the controls. The lower concentrations of 1MCP (50 and 100 ug*L1) had no effect on days to 1/4 orange for fruit stored at 5 oFor fruits stored at 20 C. oC, the highest concentration of 1MCP (200 ug*L1) extended days to 1/4 orange by 3 and 4 d for fruit harvested 1/4 yellow stage and 1/2 yellow stage, respectively. 1MCP treatments at the lower concentrations (50 and 100 ug*L1) extended the days to 1/4 orange by 3 d only for fruit harvested at t he 1/4 yellow stage.

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83 Weight loss ranged from 1.99 to 5.79% in fruit stored at 5 oC (Table 6 6). Weight loss ranged from 2.43 to 7.88% in fruit stored at 20 oAppearance Ratings C. Generally fruit harvested at the 1/4 quarter yellow stage lost more weight (5.98%) than the fruit harvested in the 1/2 yellow stage (4.50%), and fruit harvested in the 3/4 yellow stage lost the least amount of weight (2.75%). Fruit harvested at the 1/4 and 1/2 yellow stages and stored at 5 oC were unmarketable due to high incidence of fin margin browning and stem end shriveling (Table 67). These fruit also had high incidence of surface pitting/ browning. Fruit treated with 100 and 200 ug*L11MCP and stored at 20 oFirm ness C had persistently green fins rated as 2 and 3 respectively. Initial fruit firmness decreased sharply with each harvest maturity (Table 6 8). Fruit harvested at the 1/4 yellow stage had the highest initial firmness (26.0 N), fruit harvested at the 1/2 yellow stage were less firm (20.1 N), and fruit harvested at the 3/4 yellow stage were the softest (14.0 N). The firmness of the fruit decreased with the storage period; however, fruit treated with the highest concentration of 1MCP (200 ug*L1) maintained firmness significantly over the controls for all harvest ma turities when stored at 5 oC. Firmness of the fruit that were stored ranged from 7.3 to 16.2 N. The 200 ug*L1 1MCP treatment helped to maintain firmness over controls for fruit harvested at the 1/4 yellow stage and stored at 20 oCompositional Analysis C. Firmness decreased sl ightly for fruit harvested at 3/4 yellow. There were no treatment effects on the compositional parameters (Table 6 9). The soluble solids content ranged from 6.64 to 7.74 oBrix. The soluble solids content increased significantly betw een fruit harvested at each color stage. The total titratable acidity ranged from 0.224 to 0.242. The sugar to acid ratio increased significantly between fruit harvested at the 1/4 yellow

PAGE 84

84 stage and the fruit harvested at the 3/4 yellow stage, but not betwe en the fruit harvested at the 1/4 yellow stage and 1/2 yellow stage or between 1/2 yellow stage and 3/4 yellow stage. Discussion: Experiment 2 Respiration Respiration rates were not suppressed by 1MCP treatment in fruit harvested at the 1/2 yellow stage (Figure 6 3). This confirms data from experiment 1. For the treated fruit the higher respiration rates may have been caused by the fruits being damaged by a tropical storm nine days before harvest leading to an increase in respiration due to stress. Lee ( 2005) reported increased respiration in cucumbers subjected to impact stress. Days to Peak Ripeness and Weight Loss Weight loss was affected by the harvest maturity (Table 6 6). Fruit harvested at the 1/4 yellow stage took longer to reach the 1/4 orange stage, the longer storage time led to an increase in weight loss. These results are similar to the findings of Teixeira and Durigan (2006), who reported that 1MCP did not significantly delay ripening (time required to reach ripe stage) in fruit harvested at the 1/2 yellow stage. In the present experiment, the highest concentration of 1 MCP treatment did significantly delay days to 1/4 orange, but only for fruit harvested in the 1/4 and 1/2 yellow stages. Days to orange for fruit harvested in the 3/4 yellow stage was not affected by 1 MCP treatments. This is probably due to the fruit being very close to reaching the 1/4 orange stage prior to the 1MCP treatment; therefore, the 1 MCP application was not early enough to delay the onset of the 1/4 orange stage Appearance Ratings Fruit harvested at the 1/4 and 1/2 yellow stages and stored at 5 oC were unmarketable due to a high incidence of fin margin browning and stem end shriveling (Table 67). This was due to damage caused by a tropical storm nine days before harvest the low temperature storage likely

PAGE 85

85 exacerbated the browning and shriveling In this experiment fruit that were treated with the highest 1MCP concentration had a greener appearance and also persistently green fins. Fruit treated with the lower concentrations of 1MCP (50 and 100 ug*L1Firmness ) had a less green appearance. A previous report showed that 1 MCP suppressed chlorophyllase and peroxidase enzymes in broccoli florets (Gong and Mattheis, 2003). The highest concentration of 1MCP treat ment was the most effective treatment for maintaining firmness, except for fruit harvested at the 3/4 yellow stage and stored at 20 oC (Table 6 8). This was likely because the fruit already started ripening toward the 1/4 orange stage. Lower concentrations of 1 MCP (50 and 100 ug*L1Compositional Analysis ) had a minimal e ffec t on firmness. The firmness of fruit decreased with harves t maturity as also reported by Chin et al. ( 1999), due to changes in cell wall composition as the hemicellulose decreased and pectins increased. The highest concentration of 1MCP likely saturated the ethylene receptor sites while the lower concentrations did not. These results confirm the results reported previously that 1MCP can maintain the firmness of climacteric and non climacteric fruits when ap plied postharvest (Jiang et al., 2004; Bregoli et al., 2005; Martinez Romero, 2003). Titratable acidity was not affected by 1MCP treatment (Table 6 9). This was likely due to a similar storage time for the fruits. Campbell et al. ( 1987) and Siller Cepeda et al. (2004) both reported that acidity decreased with storage time. The fruit had a slightly different pH depending on the harvest maturity. Sugar to acid ratio is an important indicator of sweetness. This ratio was not significan tly influenced by the harvest maturities between 1/4 yellow and 1/2 yellow, nor between 1/2 yellow and 3/4 yellow. The fruit with the lowest ratio was the 1/4 yellow; the 3/4

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86 yellow fruit had the highest ratio. This reflects the statement made by Narain (2 001) that sugar to acid ratio increases with each color stage. Conclusions The 1methylcyclopropene (1MCP) treatments were beneficial in maintaining fruit firmness. The 1MCP treatment had no significant e ffect on the compositional parameters of the frui t, but did suppress volatile production. The 1MCP at 200 ug*L1 prevented the outer edges of the fruit fins from turning yellow. 1 MCP treatments at 50 and 100 ug*L1 had similar e ffects but at lower magnitudes. Firmness was maintained, but only slightly over the controls. Total v olatile production was also suppressed by the 1 MCP treatment The fins of the fruit had a slightly less green appearance with the lower concentrations of 1 MCP. Because 1 MCP helped to maintain firmness of treated fruits and exte nded shelf life it could be a valuable treatment for carambola that are harvested at the 1/2 yellow stage

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87 Figure 61. Respiration rate of Arkin carambola harvested at 1/4 yellow stage during ripening at 20 o C (n=3 fruits). 0 5 10 15 20 25 30 35 40 3 5 7 9 Time ater harvest (d) CO2 (ml-kg-1h-1) Control Treated

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88 Figure 6 2. Respiration rate of Arkin carambola harvested at three stages of maturity and stored at 20 o C. Three days after treatment (n=3 fruits). 0 5 10 15 20 25 1/4 Yellow 1/2 Yellow 3/4 Yellow Harvest Maturity CO2 (ml-kg-1h-1) Control 1-MCP

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89 Table 6 1. Days taken to reach 1/4 orange stage and weight loss for Arkin carambola after treatment with aqueous 1 MCP plus 14 d at respective storage temperature plus ripening at 20 o Harvest Maturity C. Storage Temperature ( o Treatment C) Days to 1/4 Orange (after transfer to 20 o Weight Loss C) 1/4 Yellow 5 C 9 Z 2.47 bc 1/2 Yellow Y 5 C 9 2 .25 c 3/4 Yellow 5 C 9 2.23 c 1/4 Yellow 5 T 11 4.20 a 1/2 Yellow 5 T 11 4.00 a 3/4 Yellow 5 T 9 3.32 ab 1/4 Yellow 10 C 9 2.73 bc 1/2 Yellow 10 C 9 3.22 ab 3/4 Yellow 10 C 3 1.19 d 1/4 Yellow 10 T 11 3.91 ab 1/2 Yellow 10 T 11 2 .90 b 3/4 Yellow 10 T 3 1.58 c 1/4 Yellow 20 C 12 1.19 d 1/2 Yellow 20 C 7 1.24 cd 3/4 Yellow 20 C 7 1.32 cd 1/4 Yellow 20 T 14 2.71 b 1/2 Yellow 20 T 12 1.27 cd 3/4 Yellow 20 T 7 1.23 cd ZC = untreated control; T = 1MCP treated. Y Wi thin each treatment (n = 4 fruit/treatment) values followed by different letters within weight loss column are significantly different at the P<0.05, according to Duncans Multiple Range Test.

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90 Table 6 2. Subjective appearance ratings for Arkin carambola fruit subjected to 1 MCP treatments and various storage temperatures. Fruit rated once upon reaching the peak ripeness stage (1/4 orange). ZC = control, untreaded; T = treated with 1MCP (200 ug*L1) Y Appearance ratings based on table 3 1. 1 = none or very little, 2 = slight, 3 = moderate, 4 = severe Harvest Maturity Storage Temperature ( o Treatment C) App earance Categories Fin Margin Browning Stem End Shriveling Surface Pitting/ Browning Persistent Green Fins 1/4 Yellow 5 C 3 Z 3 Y 2 1 1/2 Yellow 5 C 2 3 2 1 3/4 Yellow 5 C 1 1 1 1 1/4 Yellow 5 T 2 2 1 4 1/2 Yellow 5 T 1 2 1 3 3/4 Yellow 5 T 1 1 1 3 1/4 Yellow 10 C 2 2 2 1 1/2 Yellow 10 C 1 2 2 1 3/4 Yellow 10 C 1 1 1 1 1/4 Yellow 10 T 2 2 1 2 1/2 Yellow 10 T 1 1 1 2 3/4 Yellow 10 T 1 1 1 2 1/4 Yellow 20 C 2 2 1 1 1/2 Yellow 20 C 1 1 1 1 3/4 Yellow 20 C 1 1 1 1 1/4 Yellow 20 T 1 1 1 2 1/2 Yellow 20 T 1 1 1 2 3/4 Yellow 20 T 1 1 1 2

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91 Table 6 3. Firmness (maximum force through 7 mm of a 10 mm of cross section) of Arkin carambola fruit at initial stages and upon reaching the peak ripeness stage (1/4 orange). Harvest Maturity Storage Temperature ( o Initial Firmness (N) C) Final Firmness (N) Control Treated 1/4 Yellow 5 25.5 a 9. 7 a Z 16.4 a 1/2 Yellow 5 19.0 b 5.6 c 9.6 b 3/4 Yellow 5 15.8 c 5.9 c 12.3 ab 1/4 Yellow 10 25.5 a 6.4 b 13.7 a 1/2 Yellow 10 19.0 b 6.2 b 9.1 a 3/4 Yellow 10 15.8 c 7.5 b 13.3 a 1/4 Yellow 20 25.5 a 7.3 b 11.2 a 1/2 Yellow 20 19.0 b 8.4 b 12.5 a 3/4 Yellow 20 15.8 c 7.6 b 15.2 a Z Values within each column followed by different letters are significantly different at P<0.05, according to Duncans Multiple Range Test. (n = 4 fruit/treatment) Table 6 4. Selected compositional qualit y parameters for Arkin carambola harvested at three ripeness stages, treated with 1MCP and analyzed at the peak ripeness stage (1/4 orange). Harvest Maturity Compositional Parameter 1/4 Yellow z 1/2 Yellow 3/4 Yellow SSC ( o Brix) 6.40 b y 7.08 a 7.12 a TTA (%) 0.307 a 0.271 b 0.229 c pH 3.77 b 3.98 a 4.05 a SSC/TTA ratio 20.8 c 26.1 b 31.1 a ZWithin each treatment (n = 4 fruit/treatment) values followed by different letters between ripeness stages are significantly different at the P<0.05, according to Duncans Multiple Range Test. y SSC = Soluble Solids Content; TTA = Total Titratable Acidity (malic acid equivalent).

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92 Table 6 5. Headspace aroma volatiles (relative areas) analyzed at the peak ripeness stage (1/4 orange) for Arkin carambola harvested 1/4 and 1/2 yellow, as affected by 1MCP treatment and harvest maturity. Storage Temperature ( o C) 5 20 1 MCP treatment (ug*L 1 ) 0 200 0 200 Volatile RI ZY 1/4 Y X 1/2 Y W 1/4 Y 1/2 Y 1/4 Y 1/2 Y 1/4 Y 1/2 Y Alcohols 1 Pentanol 763 n.d. 7.0 V n.d. n.d. 10.2 9.7 7.2 12.0 Heptanol 974 n.d. n.d. 76.5 n.d. n.d. n.d. n.d. n.d. 1 Octanol 1071 6.3 8.8 23.2 34.7 11.8 13.6 n.d. n.d. 1 Nonanol 1167 n.d. n.d. 23.2 n.d. n.d. n.d. n.d. n.d. Aldehydes Pentanal 687 n.d. n.d. 16.9 n.d. n.d. n.d. n.d. n.d. Hexanal 801 n.d. n.d. 8.9 n.d. n.d. 22.4 12.3 n.d. Nonanal 1108 n.d. n.d. 248.7 n.d. 25.3 30.2 21.7 39.9 2 Hexenal 860 n.d. n.d. 36.9 n.d. n.d. n.d. n.d. n.d. Al kanes Undecane 1101 n.d. n.d. n.d. 7.7 n.d. 5.3 4.3 5.2 Tetradecane 1393 n.d. 28.8 n.d. n.d. n.d. n.d. n.d. n.d. D6 Phenol 978 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 Ethyl benzoate 1179 n.d. n.d. 60.1 9.7 n.d n.d. n.d. n.d. Toluene 771 n.d. n.d. n.d. n.d. 10.2 9.7 7.2 12.0 1,3 Diethenyl Benzene 1128 n.d. n.d. n.d. n.d. 65.5 27.6 75.9 n.d. 1,4 Diethenyl Benzene 1142 n.d. n.d. n.d. n.d. n.d. 4.3 n.d. n.d. Esters Acetate (E ) 2 Hexen 1 ol 1015 n.d. n.d. 11.6 n.d. n.d. n.d. n.d. n.d. Ketones Acetone 510 n.d. n.d. n.d. n.d. n.d. n.d. n.d. 5.8 3 Pentanone 684 n.d. n.d. 16.9 n.d. n.d. n.d. n.d. n.d. 2 Methyl 3 Pentanone 745 n.d. 42.1 n.d. n.d. n.d. n.d. n.d. n.d.

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93 Table 6 5. Continued Storage Temperature ( o C) 5 20 1 MCP treatment (ug*L 1 ) 0 200 0 200 Volatile RI ZY 1/4 Y 1/2 Y 1/4 Y 1/2 Y 1/4 Y 1/2 Y 1/4 Y 1/2 Y Norisoprenoids Beta Ionone 1498 n.d. n.d. n.d. n.d. 47.8 26.0 18.7 32.1 Total Alcohols 6.3 15.8 122.9 34.7 22.0 23.3 7.2 12.0 Total Aldehydes 0.0 0.0 311.4 0.0 25.3 52.6 34.0 39.9 Total Alkanes 0.0 28.8 60.1 17.4 75.7 46.9 87.4 17.2 Total Esters 0.0 0.0 11.6 0.0 0.0 0.0 0.0 0.0 Total Ketones 0.0 42.1 16.9 0.0 0.0 0.0 0.0 5.8 Total Norisoprenoids 0.0 0.0 0.0 0.0 47.8 26.0 18.7 32.1 Total Volatiles 6.3 86.7 506.1 52.1 170.7 148.9 147.4 106.9 ZWithin each treatme nt (n = 1 fruit/rep, 4 reps averaged), value represents area under the curve as a percentage of the area of the internal standard (D6phenol). YListed volatiles are significant contributors to the aroma profile of carambola found in samples from Chapter 4. Volatiles have been tentatively identified using Kovats Retention Index. XRI = Kovats Retention Index Number W1/4 Y = 1/4 Yellow, 1/2 Y = 1/2 Yellow Vn.d. = not detected in all replicate samples of a treatment

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94 15 20 25 30 35 40 2 4 6 Time after harvest (d) CO2 (ml-kg-1h-1) 0 ug/L1-MCP 50 ug/L 1-MCP 100 ug/L 1-MCP 200 ug/L 1-MCP Figure 6 3. Re spiration rate of Arkin carambola harvested at 1/2 yellow stage during ripening at 20 oC. (n=3 fruits). Data points with standard error bars.

PAGE 95

95 Table 6 6. Days taken to reach 1/4 orange stage and weight loss for Arkin carambola after treatment with aq ueous 1MCP plus 14 d at respective storage temperature plus ripening at 20 oHarvest Maturity C. Storage Temperature ( o 1 MCP Treatment (ug*L C) 1 Days to 1/4 orange (after transfer to 20 ) oWeight Loss C) 1/4 Yellow 5 0 9 4.79 a Y 1/2 Yellow 5 0 9 4.84 a 3/4 Yellow 5 0 6 2.55 c 1/4 Yellow 5 50 9 5.22 a 1/2 Yellow 5 50 9 3.62 b 3/4 Yellow 5 50 6 2.64 c 1/4 Yellow 5 100 9 5.79 a 1/2 Yellow 5 100 9 4.46 ab 3/4 Yellow 5 100 6 2.61 c 1/4 Yellow 5 200 11 3.90 b 1/2 Yellow 5 200 11 3.90 b 3/4 Yellow 5 200 6 1.99 c 1/4 Yellow 20 0 12 7.21a 1/2 Yellow 20 0 7 4.98 b 3/4 Yellow 20 0 7 2.75 c 1/4 Yellow 20 50 15 6.81 a 1/2 Yellow 20 50 7 4.65 b 3/4 Yellow 20 50 7 2.43 c 1/4 Yellow 20 100 15 7.88 a 1/2 Yellow 20 100 7 4.60 b 3/4 Yellow 20 100 7 2.80 c 1/4 Yellow 20 200 15 6.24 a 1/2 Yellow 20 200 11 4.96 b 3/4 Yellow 20 200 7 4.20 bc Z1MCP treatment concentration of a.i. (ug*L1). Y Within each treatment (n = 4 fruit/treatment) values followed by differen t letters within column are significantly different at the P<0.05, according to Duncans Multiple Range Test.

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96 Table 6 7. Subjective appearance ratings for Arkin carambola fruit subjected to 1 MCP treatments of different concentrations and two storage t emperatures. Fruit rated once upon reaching the peak ripeness stage (1/4 orange). Appearance Categories Fin Margin Browning Stem End Shriveling Surface Pitting/ Browning Persistent Green Fins Harvest Maturity Storage Temperature ( o 1 MCP Treatment (ug*L C) 1 1/4 Yellow ) 5 0 4 4 Z 3 1 1/2 Yellow 5 0 4 4 3 1 3/4 Yellow 5 0 3 4 2 1 1/4 Yellow 5 50 2 4 1 1 1/2 Yellow 5 50 2 2 1 1 3/4 Yellow 5 50 2 2 1 1 1/4 Yellow 5 100 2 3 1 2 1/2 Yellow 5 100 2 3 2 2 3/4 Yellow 5 100 3 2 1 1 1/4 Yellow 5 200 2 3 1 2 1/2 Yellow 5 200 2 3 1 3 3/4 Yellow 5 200 2 2 1 1 1/4 Yellow 20 0 2 1 1 1 1/2 Yellow 20 0 2 1 1 1 3/4 Yellow 20 0 2 1 1 1 1/4 Yellow 20 50 2 1 1 1 1/2 Yellow 20 50 1 1 2 1 3/4 Yellow 20 50 1 1 1 1 1/4 Yellow 20 100 2 1 1 2 1/2 Yellow 20 100 2 1 2 2 3/4 Yellow 20 100 2 1 1 2 1/4 Yellow 20 200 2 1 1 3 1/2 Yellow 20 200 2 1 1 3 3/4 Yellow 20 200 1 1 1 3 Based on Table 3 1. 1=little or none, 2=slight, 3=moderate, 4=severe

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97 Tab le 6 8. Firmness ( maximum force throught 7 mm of a 10 mm cross section) of Arkin carambola fruit at initial stages and upon reaching the peak ripeness stage (1/4 orange). Final Firmness (N) Harvest Maturity Storage Temperature ( o Initial Firmn ess (N) C) 1 MCP Concentration (ug*L 1 ) 0 50 100 200 1/4 Yellow 5 26.0 a 9.1 c Z 10.6 b Y 8.6 c 10.8 b 1/2 Yellow 5 20.1 b 7.3 d 8.5 c 10.1 b 9.1 c 3/4 Yellow 5 14.0 c 8.7 c 9.6 bc 9.5 bc 9.9 b 1/4 Yellow 20 26.0 a 8.0 d 8.5 c 7.6 cd 8.7 c 1/ 2 Yellow 20 20.1 b 11.1 b 9.1 c 8.7 c 8.7 c 3/4 Yellow 20 14.0 c 15.6 a 11.9 ab 14.9 a 16.2 a Z Values within Initial column followed by different letters are significantly different at P<0.05, according to Duncans Multiple Range Test. (n = 4 fruit/trea tment) Y Within each treatment (n = 4 fruit/treatment) values followed by different letters within the final firmness columns are significantly different at the P<0.05, according to Duncans Multiple Range Test. Table 6 9. Selected compositional qua lity parameters for Arkin carambola harvested at three ripeness stages, treated with 1MCP at three concentrations and analyzed at the peak ripeness stage (1/4 orange). Compositional Parameter 1/4 Yellow z 1/2 Yellow 3/4 Yellow SSC ( o Brix) 6.64 c y 7.1 1 b 7.74 a TTA (%) 0.224 b 0.227 b 0.242 a pH 3.91 b 4.06 a 4.07 a SSC/TTA Ratio 29.667 b 31.329 ab 32.030 a ZWithin each treatment (n = 4 fruit/treatment) values followed by different letters between ripeness stages are significantly different at the P<0.05, according to Duncans Multiple Range Test. y SSC = Soluble Solids Content; TTA = Total Titratable Acidity (malic acid equivalent).

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98 CHAPTER 7 EFFECTS OF POSTHARVEST TREATMENTS OF AQU EOUS 1 MCP AND ETHYLENE TO ARKIN CARAMBOLA FRUIT QUAL ITY Introduction In previous experiments (Chapter 6) postharvest application of aqueous 1methylcyclopropene (1 MCP) was shown to be an effective agent in maintaining fruit firmness and extending shelf life (Chapter 6). The 1 MCP treatments that were most effective i n maintaining fruit firmness also caused persistently green fins. 1MCP has been reported to maintain fruit firmness and extend the shelf life of other types of fruit (Sisler et al., 1996a; Sisler and Serek, 1999; Jiang et al., 2004). 1MCP has been report ed to maintain color in Fwang Tung carambola fruit, but this was not described as a negative effect (Teixeira and Durigan, 2006). Exogenous ethylene applications are used commercially to degreen non climacteric fruit s Climacteric fruits frequently trea ted with ethylene include tomatoes and bananas; nonclimacteric fruits frequently treated with ethylene include oranges, grapefruits, and lemons. Generally optimal ripening conditions for fruits are; 18 to 25 oC, high relative humidity (90 95%), and ethyle ne concentrations ranging from 10 to 100 ppm (Reid, 2002). In the experiment outlined in Chapter 5 the 100 ppm treatment had the highest degreening effect for carambola. Exogenous ethylene stimulate s chlorophyllase and peroxidase activity which degrade chl orophyll and cause degreening (Amir Shapira et al., 1987). Postharvest ethylene treatments did not affect soluble solids content or titratable acidity of carambola fruit or other nonclimacteric fruits (Sargent and Brecht, 1990; Tian et al., 2000). Exogenous ethylene treatments were associated with fruit developing over ripe flavor volatiles and causing an increase in stem end shriveling and surface pitting/ browning (Chapter 5). The objective of this experiment was to determine the

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99 effectiveness of exogeno us ethylene treatment applied post 1 MCP treatment The hypothesis was that exogenous ethylene would aid in overcoming the persistent green fins caused by 1MCP Material and Methods Plant Material Arkin Carambolas were handharvested into plastic con tainers (up to three layers deep) at 1/4 yellow, 1/2 yellow and 3/4 yellow color stages in Pine Island, FL on the morning of February 5th, 2008. The commercial grower was Brooks Tropicals (Homestead, Florida). Harvested fruit was transported in the plastic containers to the Postharvest Horticulture Laboratory at the University of Florida, Gainesville by car the same day. The fruit were stored overnight in the plastic conta iners in at 10 oTreatment with Aqueous 1 MCP C The following morning, fruits were then selected based on color sta ge, washed and randomized into respective treatments; fruit were segregated for respiration and initial firmness measurements. Aqueous application of 1 MCP was performed as described in Chapter 6. Storage and Ethylene Treatment Carambola fruit were stored in 175 L sealed containers on plastic trays with flow through air containing 100 ppm ethylene for 24 or 48 h at 20 oC 90% R.H. The mixed gasses were humidified by bubbling through a water filled jar before entering the chamb er. After the gassing treatments the fruit w ere stored at 20 oC until reaching the 1/4 orange stage. There were no 3/4 yellow fruit used in 20 oC storage treatment because the fruit would have reached the 1/4 orange stage prior to the ethylene treatment.

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100 Quality Analyses Fruit was rated subjectively for appearance based on Table 3 1. Preparation for compositional analysis for SSC, TTA and pH were done as described in Chapter 2. Firmness was measured as described in Chapter 6. Volatiles were measured as des cribed in Chapter 3. Statistical Analyses Statistical analyses were performed according to the procedures outlined in Chapter 2. Results Days to Peak Ripeness and Weight Loss Days to reach peak ripeness (1/4 orange), after 14 d storage at 5 oC, including the ethylene treatment, ranged from 7 to 13 d for fruit stored at 5 oC (Table 7 1). Days to reach the 1/4 orange stage for fruit stored at 20 oC ranged from 2 to 7 d. For fruit harvested at the 1/4 and 1/2 yellow stages, stored at 5 oC, t he 1MCP treat ment dela yed days to 1/4 orange by 3 d Fruit harvested at the 3/4 yellow stage took the same amount of time to reach the 1/4 orange stage whether they were treated with 1 MCP or not. Weight loss ranged from 1.69 to 7.80% of initial weight in fruit stored at 5 oC after the 1 MCP treatment. Weight loss ranged from 3.93 to 11.43% of initial weight in fruit stored at 20 oC. For the fruit stored at 5 oC and then gassed for 48 h, the 1 MCP treatment increased weight loss. Fruit harvested at the 1/4 and 1/2 yell ow stages which were treated with 1 MCP, stored at 20 oAppearance Ratin gs C and gassed for 48 hours lost the most weight. Persistent green fins remained on fruit treated with 1 MCP (Table 7 2). Persistently green fins were rated as a 4 for fruit harvested at the 1/4 and 3/4 yellow stages and treated

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101 with 1 MCP, even when treated with 48 h ethylene. The 48 h ethylene treatment increased the incidence of surface pitting/ browning. The 48 h ethylene treatment also increased the incidence of fin margin brownin g for fruit stored at 20 oFirmness C. Initial firmness values ranged from 24.7 to 14.9 N (Table 73). Fruit harvested at the 1/4 yellow stage (24.7) were significantly firmer than fruit harvested at the 1/2 yellow stage (18.6 N) and 3/4 yellow stage (14.9 N). Fruit firmness decreased with the storage period. Final fruit firmness ranged from 5.3 to 12.8 N. 1MCP treated fruit were significantly firmer than non1MCP treated fruit when stored at 5 oC and treated with 48 h ethylene. 1 MCP treated fruit were al so significantly firmer than non1MCP treated fruit when stored at 20 oCompositional Analysis C and treated with 24 h ethylene. There were no treatment effects on the compositional parameters of the fruit (Table 74). The soluble solids content of the fr uit ranged from 6.70 to 8.02 oBrix. Fruit harvested at the 1/4 yellow stage had the lowest soluble solids content (6.70 oBrix), while fruit harvested at the 1/2 and 3/4 yellow stages had higher soluble solids content (7.16 and 8.02 oBrix respectively). Th e total titratable acidity r anged from 0.231 to 0.286. F ruit harvested at the 1/4 yellow stage had the highest total titratable acidity (0.286), while fruit harvested in the 1/2 and 3/4 yellow stages had lower total titratable acidity (0.264 and 0.231), re spectively. The sugar to acid ratio ranged from 23.819 to 35.666 and increased significantly at each harvest maturity.

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102 Volatiles Initial volatiles were measured in the harvest maturity experiment of Chapter 4. For this experiment fruit were analyzed upon reaching the peak ripeness stage (1/4 orange). For fruit harvested at the 1/4 yellow stage ethanol was detected only when fruit were treated with 24 h ethylene, regardless of 1MCP treatment (Table 7 5). 1pentanol was found only in the fruit not treated w ith 1 MCP and treated with 48 h ethylene. Norisoprenoid compounds are associated with carotene breakdown and off flavor formation (Table 4 3), were found to be highest in fruit that received the 48 h ethylene treatment. For fruit not treated with 1 MCP, t he 48 h ethylene treatment increased total volatile formation by 64% over the 24 h ethylene treatment. For fruit treated with 1 MCP, the 48 h ethylene treatment increased total volatile formation by 134% over the 24 h ethylene treatment. Ethanol was not de tected in any of the fruit harvested at the 1/2 yellow stage (Table 76). There were higher amounts of 1octanol and 1nonanol in fruit treated with 48 h ethylene than fruit treated with 24 h ethylene. Nonanal was higher in fruit treated with 48 h ethylene than in fruit treated with 24 h ethylene. For non1 MCP treated fruit, nonanal was 167% higher in fruit treated with 48 h ethylene over the fruit treated with 24 h ethylene. For 1 MCP treated fruit, nonanal was 206% higher in fruit treated with 48 h ethyl ene over fruit treated with 24 h ethylene. The same trend existed for tetradecane. For non1 MCP treated fruit, the 48 h ethylene treatment increased total volatile formation by 96% over the 24 h ethylene treatment. For fruit treated with 1MCP, the 48 h ethylene treatment increased total volatile formation by 71% over the 24 h ethylene treatment.

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103 Total volatiles were higher in fruit harvested at the 1/4 yellow stage than fruit harvested at the 1/2 yel low stage. When comparing fruit harvested at the 1/2 ye llow stage to fruit harvested at 1/4 yellow that were not treated with 1 MCP total volatiles were 229% and 175% higher for fruit treated with 24 and 48 h ethylene respectively. When comparing fruit treated with 1 MCP and harvested at the 1/2 yellow or 1/ 4 yellow stage total volatiles were 232 % and 355% higher for fruit treated with 24 and 48 h ethylene respectively. Discussion Days to Peak Ripeness and Weight Loss Days to peak ripeness (1/4 orange) w ere delayed by 1 MCP treatments for fruit harvested at the 1/4 and 1/2 yellow stages and stored at 5 oC (Table 7 1). The days to 1/4 orange w ere also delayed by the 1 MCP treatment for fruit harvested at 1/4 and 1/2 yellow, stored at 20 oC, and exposed to 48 h ethylene. Generally, fruit with the longest stor age time lost the most weight. Also, fruit stored at 20 oC lost more weight than fruit stored at 5 oC. This was possibly caused by slower metabolic rates in fruit stored at the lower temperature. These results are similar to those reported by Campbell et al. (1989) who reported that carambola stored for 44 d at 5 or 10 oC lost more weight than fruit stored for 14 d at the same temperatures. They also reported that color change and ripening were delayed in fruit stored at 5 oC compared to those stored at 10 oAppearance Ratings C. These also parallel the results in Chapters 3, 5, and 6. T he 1 MCP treatment maintained the green color of the fruit (Table 7 2). In previous reports 1MCP has been shown to reduce chlorophyllase and peroxidase activities, both of which are responsible for chlorophyll degradation and degreening

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104 (Gong and Mattheis, 2003). Color maintenance has been reported in Fwang Tung carambola (Teix eira and Durigan, 2006). In the present experiment the ethylene treatment after the storage perio d did little to degreen the fruit that were treated with 1 MCP. It is possible that the ethylene was not binding to the receptor sites on the fruit because t hey were already occupied by 1MCP. The ethylene treatment reduced the visual quality of the fruit, making the fin margins and surface more brown. This was likely due to ethylene stimulating production of phenolics Ethylene treatments have been reported to increase the incidence of peel scald, stem end breakdown, fin browning, and mold growth for caram bola fruit treated prior to cold treatment (Miller and McDonald, 1997). Firmness The firmness of carambola fruit was maintained by 1 MCP treatments only for specific combinations of temperature and ethylene exposure (Table 7 3). For fruit stored at 5 oC a nd then subjected to 48 h ethylene, the 1MCP treatment helped maintain firmness significantly over fruit not treated with 1 MCP. The 1MCP treatment also maintained firmness for fruit stored at 20 oCompositional Analysis C and then subjected to 24 h ethylene. The 1MCP treatme nts probably maintained turgidity of the fruit as they were subjected to the ethylene treatments. A previous report showed that 1MCP treatments to vegetables including; bok choy and choy sum can maintain their turgidity postharvest (Thomson et al., 2003), which parallels the results shown here. The compositional parameters were not significantly affected by treatments (Table 74). Ethylene did not affect the SSC of carambola in a previous report (Sargent and Brecht, 1990). Similarly, ethylene treatments on strawberry fruit that have been treated with 1 MCP have been shown not to affect the soluble solids content (Tian et al., 2000).

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105 Volatiles Ethanol was detected only in fruit which were harvested at the 1/4 yellow stage, not treated with 1 MCP, stored at 5 oConclusions C, and for 24 h with ethylene (Table 75). The ethanol was likely a byproduct of anaerobic respiration caused by a high metabolic rate and long storage time. Ethanol production has been associated with high respiration rates in apples (Forney et al., 2000) The norisoprenoid compounds were higher in fruit treated with ethylene for 48 h. This was likely due to an increase in carotene production and breakdown from extended ethylene exposure. A previous report showed that exogenous et hylene application stimulated carotene formation in citrus fruit (Rodrigo and Zacarais, 2006). The total volatiles were higher in fruit treated with 48 h ethylene. This was likely due to specific effects of ethylene on some volatile biosynthetic pathways as well as a general increase in the rate of physiological processes, which produced an increased amount of volatiles For fruit harvested at the 1/2 yellow stage, total volatiles were also higher in the fruit treated with 48 h ethylene than in fruit treate d with 24 h ethylene (Table 7 6). Similar results for an increase in metabolic rate after ethylene exposure have been reported in citrus (Eaks, 1970). When ethylene was used as an antidote to the 1MCP treatment, the outer fins of the fruit we re only slightly degreened. Since this treatment occurred 14 d after the 1MCP treatment, surface pitting/browning and fin margin browning were exacerbated. The ethylene treatment post 1 MCP treatment and storage caused the fruit to produce aroma volatiles associated with over ripe fruit Therefore, ethylene treatment post 1MCP treatment and storage is not beneficial.

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106 Table 7 1. Days to reach 1/4 orange stage and weight loss for Arkin carambola after treatment with aqueous 1 MCP, 14 d storage at respec tive temperature, and ethylene treatment at 20 o Harvest Maturity C. Storage Temperature ( o 1MCP Treatment (ug*L C) 1 100 ppm Ethylene Treatment (h) ) Days to 1/4 Orange Weight Loss (%) Z 1/4 Yellow 5 0 24 10 4.67 c Y 1/2 Yellow 5 0 24 10 4.44 c 3/4 Yellow 5 0 24 7 2.11 d 1/4 Yellow 5 0 48 10 2.55 d 1/2 Yellow 5 0 48 10 1.69 d 3/4 Yellow 5 0 48 7 2.13 d 1/4 Yellow 5 200 24 13 7.80 b 1/2 Yellow 5 200 24 13 4.71 c 3/4 Yellow 5 200 24 7 5.56 bc 1/4 Yellow 5 200 48 13 6.34 bc 1/2 Ye llow 5 200 48 13 6.22 bc 3/4 Yellow 5 200 48 7 4.91 c 1/4 Yellow 20 0 24 2 7.87 b 1/2 Yellow 20 0 24 2 4.68 c 1/4 Yellow 20 0 48 2 5.51 c 1/2 Yellow 20 0 48 2 4.92 c 1/4 Yellow 20 200 24 2 3.93 cd 1/2 Yellow 20 200 24 2 5.43 c 1/4 Yellow 20 200 48 7 11.43 a 1/2 Yellow 20 200 48 7 6.09 bc ZDays to reach 1/4 orange stage after 14 d storage period. YWithin each treatments (n = 4 fruit/ treatment) values followed by different letters within column are significantly differ ent at the P<0.05, according to Duncans Multiple Range Test.

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107 Table 7 2. Subjective appearance ratings for Arkin carambola fruit subjected to 1 MCP treatments at 5 and 20 o C. Fruit rated once reaching the peak ripeness stage (1/4 orange). Appearan ce Categories Fin Margin Browning Stem End Shriveling Surface Pitting/ Browning Persistent Green Fins Harvest Maturity Storage Temperature ( o 1 MCP Treatment (ug*L C) 1 Ethylene Treatment (h) ) 1/4 Yellow 5 0 24 3 2 2 3 1/2 Yellow 5 0 24 1 2 1 2 3/4 Yellow 5 0 24 1 2 2 1 1/4 Yellow 5 0 48 3 2 2 3 1/2 Yellow 5 0 48 1 2 1 2 3/4 Yellow 5 0 48 1 2 2 3 1/4 Yellow 5 200 24 2 2 2 4 1/2 Yellow 5 200 24 2 2 2 3 3/4 Yellow 5 200 24 1 2 3 4 1/4 Yellow 5 200 48 3 2 3 4 1/2 Yellow 5 200 48 1 2 1 3 3/4 Yellow 5 200 48 1 2 4 4

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108 Table 7 2 Continued Appearance Categories Harvest Maturity Storage Temperature ( o 1 MCP Treatment (ug*L C) 1 Ethy lene Treatment (h) ) Fin Margin Browning Stem End Shriveling Surface Pitting/ Browning Persistent Green Fins 1/4 Yellow 20 0 24 2 2 2 1 1/2 Yellow 20 0 24 2 2 2 2 1/4 Yellow 20 0 48 3 3 1 1 1/2 Yellow 20 0 48 3 2 1 1 1/4 Yell ow 20 200 24 2 2 2 3 1/2 Yellow 20 200 24 1 2 2 3 1/4 Yellow 20 200 48 1 1 3 4 1/2 Yellow 20 200 48 2 2 2 3 B ased on Table 3 1. 1=little or none, 2=slight, 3=moderate, 4= severe

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109 Table 7 3. Firmness (maximum force of cross section) of Arkin carambola fruit at initial stages and upon reaching the peak ripeness stage (1/4 orange). Harvest Maturity Storage Temperature ( o 1 MCP C) 2Treatment (ug*L1 Ethylene Treatment (h) ) Initial Firmness (N) Final Firmness (N) 1/4 Yellow 5 0 24 24.7 a 9.6 aZ Y 1 /2 Yellow 5 0 24 18.6 b 5.9 cd 3/4 Yellow 5 0 24 14.9 c 6.3 c 1/4 Yellow 5 0 48 24.7 a 9.8 a 1/2 Yellow 5 0 48 18.6 b 5.3 d 3/4 Yellow 5 0 48 14.9 c 6.2 c 1/4 Yellow 5 200 24 24.7 a 7.6 bc 1/2 Yellow 5 200 24 18.6 b 9.8 a 3/4 Yellow 5 200 24 14.9 c 10.0 a 1/4 Yellow 5 200 48 24.7 a 8.4 b 1/2 Yellow 5 200 48 18.6 b 7.9 b 3/4 Yellow 5 200 48 14.9 c 8.2 b 1/4 Yellow 20 0 24 24.7 a 7.2 c 1/2 Yellow 20 0 24 18.6 b 6.8 c 1/4 Yellow 20 0 48 24.7 a 6.7 c 1/2 Yellow 20 0 48 18.6 b 6.9 c 1/4 Yellow 20 200 24 24.7 a 12.8 a 1/2 Yellow 20 200 24 18.6 b 11.9 a 1/4 Yellow 20 200 48 24.7 a 6.2 c 1/2 Yellow 20 200 48 18.6 b 7.7 bc Z Within each treatment (n = 4 fruit/treatment) values followed by different letters within the initial column are significantly different at the P<0.05, according to Duncans Multiple Range Test. Y Within each treatment (n = 4 fruit/treatment) values followed by different letters within the final firmness columns are significantly different at the P<0.05, according to Duncans Multiple Range Test.

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110 Table 7 4. Selected compositional quality parameters for Arkin carambola harvested at three harvest maturities, treated with 1 MCP and ethylene, and analyzed at the peak ripeness stage (1/4 orange). Compositional Parameter 1/4 Yellow z 1/2 Yellow 3/4 Yellow SSC (oBrix) 6.70 c y 7.16 b 8.02 a TTA (%) 0.286 a 0.264 b 0.231 c pH 4.07 c 4.17 b 4.30 a SSC/TTA ratio 23.819 c 27.904 b 35.666 a ZWithin each treatment (n = 6 fruit/treatmen t) values followed by different letters between ripeness stages are significantly different at the P<0.05, according to Duncans Multiple Range Test. y SSC = Soluble Solids Content; TTA = Total Titratable Acidity (malic acid equivalent).

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111 Table 7 5. Hea dspace aroma volatiles (relative areas) for Arkin Carambola harvested at 1/4 yellow, as affected by 1 MCP treatment, storage at 5 o C, and ethylene treatment analyzed at full ripe stage. Treatment Combination Volatile RI Z MCP+24 Eth Y Water+48 Et h X MCP+24 Eth Water+48 Eth Alcohols Ethanol 491 39.1 n.d. 60.2 W n.d. 1 Pentanol 763 n.d. 3235.3 n.d. n.d. 1 Octanol 1071 21.8 42.5 82.5 89.9 1 Nonanol 1167 59.1 64 97 76.3 Aldehydes Pentanal 687 11 20.5 16.3 17.3 Hexanal 801 15 17.2 39 22.9 Nonanal 1108 2130 720.5 1722.4 4682.9 2 Hexenal 860 22.8 130.5 330.4 252 Alkanes Nonane 906 5.7 n.d. n.d. 472.4 Decane 1006 13.6 n.d. n.d. 19.3 Undecane 1101 41.6 n.d. n.d. n.d. Tetradecane 1393 n.d. 11.7 1 8 53.3 Aromatic Benzene Derivatives D6 Phenol 978 V 100 100 100 100 Esters Ethyl butyrate 797 309.1 55.5 99.4 173.2 Ethyl ether 516 n.d. n.d. 15.8 14 Ketones 3 Pentanone 684 V 11 20.5 16.3 17.3 4 Heptanone 877 47.7 70.7 6 1.3 74.9 Norisoprenoids Megastigma 4,6(E) 1370 8.3 65.2 26.3 71.7 (8)Z triene Beta Ionone 1498 n.d. 44 16.2 16.6 Total Alcohols 120 3341.8 239.7 166.2 Total Aldehydes 2178.8 888.7 2108.1 4975.1 Total Alkanes 4406 60.9 11.7 18 T otal Esters 1313 309.1 55.5 115.2 Total Ketones 47.7 70.7 61.3 74.9 Total Norisoprenoids 8.3 109.2 42.5 88.3 Total Volatiles 2724.8 4477.7 2584.7 6036.7 ZWithin each treatment (n = 1 fruit/rep, 3 reps averaged), value represents area of curve as a percentage of the area of the internal standard (D6 phenol).Listed volatiles are significant contributors to the aroma profile of carambola found in initial samples. Volatiles have been tentatively identified using Kovats Retention Index (RI). YRI = Kovats Ret ention Index XTreatment combinations: Water = untreated control, MCP = treated with 200 ug*L1 aqueous 1MCP, +24 = 24 h ethylene treatment post storage, +48 = 48 h ethylene treatment poststorage. W n.d. = not detected in all replicates of the same treat ment. V Internal standard added to tentatively quantify peak areas. Only D6 phenol was used in calculating relative areas.

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112 Table 7 6. Headspace aroma volatiles (relative areas) for Arkin carambola harvested at 1/2 yellow as affected by 1 MCP treatment, storage at 5 o C, and ethylene treatment analyzed at full ripe stage. Treatment Combination Volatile RI Z MCP+24 Eth Y Water+48 Eth X MCP+24 Eth Water+48 Eth Alcohols 1 Octanol 1071 43.1 70.4 33.5 52.7 1 Nonanol 1167 74.9 113.2 48 84 Aldehy des Pentanal 687 15 17.1 18.7 68.7 Hexanal 801 13.5 20.1 19.9 21.8 Nonanal 1108 377 1005.9 244.9 748.5 2 Hexenal 860 101 127.1 175.3 172.3 Alkanes Tetradecane 1393 7.9 22.2 7.8 11.3 Aromatic Benzene Derivatives D6 Phe nol 978 V 100 100 100 100 Esters Ethyl butyrate 797 20.7 n.d. n.d. W n.d. Ethyl ether 516 17.3 9 29.3 n.d. Ketones 3 Pentanone 684 V 15 17.1 18.7 68.7 4 Heptanone 877 45.9 57 52.3 57.1 Norisoprenoids Megastigma 4,6(E) 1370 86.8 137.6 58.9 88.2 (8)Z triene Beta Ionone 1498 25.9 48.5 89.1 23.1 Total Alcohols 118.0 183.6 81.5 136.7 Total Aldehydes 506.5 1170.2 458.8 1011.3 Total Alkanes 7.9 22.2 7.8 11.3 Total Esters 38.0 9.0 29.3 0.0 Total Ketones 60.9 7 4.1 71.0 125.8 Total Norisoprenoids 112.7 186.1 148.0 111.3 Total Volatiles 829.3 1628 777.7 1327.7 ZWithin each treatment (n = 1 fruit/rep, 3 reps averaged), value represents area of curve as a percentage of the area of the internal standard (D6 phenol ).Listed volatiles are significant contributors to the aroma profile of carambola found in initial samples. Volatiles have been tentatively identified using Kovats Retention Index (RI). YRI = Kovats Retention Index XTreatment combinations: Water = untreate d control, MCP = treated with 200 ug*L1 aqueous 1MCP, +24 = 24 h ethylene treatment post storage, +48 = 48 h ethylene treatment poststorage. W n.d. = not detected in all replicates of the same treatment. V Internal standard added to tentatively quantif y peak areas. Only D6 phenol was used in calculating relative areas.

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113 CHAPTER 8 COST OF APPLYING 1 MCP TO PERMIT TREERIPE HARVEST OF AR KIN CARAMBOLA IN FLORIDA Introduction The tropical fruit industry in Florida is worth an estimated value of $75 million. Carambola constitutes 13% ($9.5 million) of the total annual revenues for all tropical fruit produced in Florida (Kahout, 2004; J.H. Crane, personal communication). The Florida crop of carambola has two major harvest seasons: August to September and D ecember to February. The trees can be strategically pruned and manipulated to bear fruit in the off season, however since the cost of labor is high this is not done on a large scale commercially (Nunez Elisa and Crane, 2000). Arkin is a sweet variety of carambola, selected during the 1970s by Morris Arkin. Currently Arkin constitutes 95% of the Florida crop (J. Crane, personal communication). Carambolas are fairly well known by consumers. Only mangos, avocados, and papayas were rated as more familiar tropical fruits (Degner, 1997). Retailers can greatly influence the way carambolas are sold. Some grocery stores stock carambola to make the produce section more visually appealing even though they do not expect to sell many of them, therefore they do not stock the fruit continuously. Other grocery stores stock the fruit whenever it is in season; they also purchase fruit grown in foreign countries to supplement the supply from Florida. If the carambolas are not sold promptly, then they may be sliced and add ed to fresh cut fruit salads (S. McManus, personal communication). For produce buyers quality is the top concern, especially the appearance of the fruit. The biggest complaint that buyers have about carambola is bruising of the ribs (Degner, 1997). As dem onstrated in this research, postharvest 1MCP treatments can help

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114 to prevent bruising by maintaining the fruit firmness. Data from the experiments in Chapter 6 demonstrated that a postharvest 1MCP treatment for carambola can limit postharvest losses. 1MC P treatments extended days to peak ripeness stage by 2 d when fruit harvested at 1/4 and 1/2 yellow were stored at 5 or 10 oC. There was a similar trend for fruit harvested at 1/4 and 1/2 yellow and stored at 20 oThe objective of this analysis was to create a sensitivity formula to eva luate the costs of adding a postharvest 1methylcyclopropene (1MCP) treatment to carambola. C. 1MCP treatment maintained firmness of fruit over the controls, which may help to prevent bruising. 1 MCP treatments might make it feasible to have a harvest later than the 1/4 yellow stage. Harvesting the fruit later than the 1/4 yellow stage will yield sweeter fruit (Chapter 4). However, the fruit would have to stay on the tree up to ten days longer and they may be subjected to possible wind damage. Also, if fruit are left on the tree longer the harvest season might start later and the new fruit set might be suppressed. This can be overcome by selective pruning. Selective pruning techniques can promote an earlier harvest season (Nunez Elisa and Crane, 2000). It is difficult to estimate the actual costs of implementing 1 MCP treatments. The gaseous treatment is sold as the SmartFresh Quality Sys tem, which is a service provided by the AgroFresh Company. Gaseous applications of 1MCP have similar effects to aqueous applications (Choi et al., 2008). Representatives from AgroFresh were unable to quote the cost of the service. A conservative estimate of the cost per box is $2, which would make it beneficial to producers and buyers to purchase the service. The 1MCP treatment could potentially reduce shrink and extend shelf life.

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115 Postharvest 1MCP treatments have proven to be effective in maintaining fruit firmness and extending shelf life by extending days to peak ripeness. Current Costs The current production cost per acre for carambola in Florida is $15,838 (Based on a 50acre operation). Harvest and marketing costs constitute $9,750 of the per acre cost (Univ. of Fla. /IFAS, 2008). Economies of scale dictate that larger operations are able to control costs better and be more vertically integrated. A vertically integrated tropical fruit company may have its own packinghouse and therefore is able to apply postharvest treatments to their products. A larger and horizontally integrated compa ny also has an advantage with labor. Keeping seasonal labor available would be easier for larger companies that also produce other crops. Larger companies can provide a permanent source of work and do not have to rely on third party labor companies for sea sonal help (Roka, 2002). Methods A sensitivity analysis was performed to determine the costs of adding postharvest 1MCP treatments to carambola. Since liquid 1 MCP is not available commercially, cost data was based on use of the gaseous application method. The cost of application was estimated in a range from $0.00 to $3.50 per box. A large range was used to ensure that the actual cost of 1 MCP treatment per box of carambola would fall within the range. The estimated cost of application was added to the average price per box of terminal markets in seven major U.S. cities. The average price per box was attained by averaging the price per box of carambola shipped from Florida for 3 weeks: the weeks of September 6, October 11, and November 1, 2008 (State of Florida, 2008b). The lowest price for a box containing 25 fruit was $8.00 in Philadelphia during the week of September 6th,

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116 2008. The highest price for a box containing 25 fruit was $27.50 in Pittsburgh during the same week. Prices per box were separated a ccording to fruit size. The terminal markets were: Atlanta, Chicago, Columbia, Dallas, Detroit, Philadelphia, and Pittsburgh. The price per box fluctuated with season and location of the terminal market. To calculate the price increase from the additional 1MCP treatments a sensitivity calculator was developed. The calculator can be used for specific input variables (Object 81). The sensitivity formula was calculated according to Equation 81. (8 1) where Y = the retail price per fruit; M = the cost per box of 1 MCP treatment; P boxPercent markup was added to the price per box at the terminal markup. Thirty four percent of fresh produce is sold to retailers from terminal markets, 24.6% of fresh produce is sold to retailers from broker/dealers, and 41.1% of fresh produce is s old to retailers directly from s hippers. Percent price markup changes depending on the distribution channel a product takes. Larger grocery retailers (more than $1.5 billion in annual sales) are more likely to purchase fresh produce directly from producers while smaller grocery retailers purchase fresh produce from wholesalers and/or distributors that are supplied by terminal markets (McLaughlin and Perosio, 1994). Distributors price markup ranges from 25% to 30%, wholesalers price markup ranges from 10% to 20%, and retailers price markup ranges from 30% to 50% (Wolfe, 1999). These markups are compounded and the price markup range from the terminal price is 30% to 115%. = the wholesale price per box of carambola; n = the number of fruit in a box or sizing number of fruit in a box (20s = 20 fruit per box); Markup = the percentage markup of the re tailer. Y= (M + P box ) (n) [ 1.0 + % Markup

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117 Results For a 20 count box of carambola the additional cost of 1MCP treatment per f ruit was calculated to range from $0.03 to $0.18 at the breakeven level (Table 8 1). For a 25count box of carambola the additional cost of 1MCP treatment per fruit ranged from $0.02 to $0.14 at the breakeven level (Table 8 2). During the months September through November 2008, 25count boxes were the median size for carambola sales in the United States. For a 30 count box of carambola the additional cost of 1MCP treatment per fruit ranged from $0.01 to $0.11 at the break even level (Table 8 3). The pr ice range of an individual fruit at the retail level is affected by the percent markup; the range gets wider as the percentage markup increases. Discussion Results from this present study have shown that postharvest 1MCP treatments for carambola have prov en to be beneficial for maintaining fruit firmness and extending shelf life. The cost of adding postharvest 1MCP treatments has proven to be feasible. Since a box of carambola typically contains 20 to 30 fruit the increase in breakeven price for a box of treated fruit would only be 7 to 18 cents per fruit. This increase is small enough to easily be passed on to the end consumer. The retail price of fresh produce swings more than other items sold in a grocery store due to production season and supply. The retail prices of fresh and lightly processed produce increase faster than they decrease in response to the increase in terminal prices (Sexton et al., 2003). Conclusions Visual quality is the most important concern for produce buyers. Carambola is a unique fruit that can benefit from postharvest 1MCP treatments to maintain quality, particularly visual quality. Based on the assumptions used in this analysis, the costs of

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118 postharvest 1MCP treatments for the fruit are small and the possible benefit from re ducing postharvest losses is large. Therefore it is feasible to treat carambola grown in Florida with postharvest application of 1MCP.

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119 Table 8 1. Estimated retail price per fruit of 1 MCP treated carambola, including a range of markup percentages (based on $18.45 for a box of 20 carambola ). Estimated retail price per fruit ($ per individual fruit) Increase in price per box ($) New price per box (size 20/box) Break Even 30% M arkup 45% Markup 60% Markup 75% Markup 100% Markup 115% Markup 0.00 18.45 0.92 1.20 1.34 1.48 1.61 1.85 1.98 0.50 18.95 0.95 1.23 1.37 1.52 1.66 1.90 2.04 1.00 19.45 0.97 1.26 1.41 1.56 1.70 1.95 2.09 1.50 19.95 1.00 1.30 1.45 1 .60 1.75 2.00 2.14 2.00 20.45 1.02 1.33 1.48 1.64 1.79 2.05 2.20 2.50 20.95 1.05 1.36 1.52 1.68 1.83 2.10 2.25 3.00 21.45 1.07 1.39 1.56 1.72 1.88 2.15 2.31 3.50 21.95 1.10 1.43 1.59 1.76 1.92 2.20 2.36

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120 Table 8 2. Estimated retail price per fruit of 1 MCP treated carambola, including a range of markup percentages (based on $20.15 for a box of 25 carambola). Estimated retail price per fruit ($ per individual fruit) Increase in price per box ($) New price per box (size 25/box) Break Even 30% M arkup 45% Markup 60% Markup 75% Markup 100% Markup 115% Markup 0.00 20.15 1.01 1.31 1.46 1.61 1.76 2.02 2.17 0.50 20.65 1.03 1.34 1.50 1.65 1.81 2.07 2.22 1.00 21.15 1.06 1.38 1.53 1.69 1.85 2.12 2.27 1.50 21.65 1.08 1.41 1.57 1.73 1.89 2.17 2.33 2.00 22.15 1.11 1.44 1.61 1.77 1.94 2.22 2.38 2.50 22.65 1.13 1.47 1.64 1.81 1.98 2.27 2.44 3.00 23.15 1.16 1.51 1.68 1.85 2.03 2.32 2.49 3.50 23.65 1.18 1.54 1.71 1.89 2.07 2.37 2.54

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121 Table 8 3. Estimated retail price per fruit of 1 MCP treated carambola, including a range of markup percentages (based on $22.73 for a box of 30 carambo la). Estimated retail price per fruit ($ per individual fruit) Increase in price per box ($) New price per box (size 30/box) Break Even 30% M arkup 45% Markup 60% Markup 75% Markup 100% Markup 115% Markup 0.00 22.73 1.14 1.48 1.65 1.82 1.99 2.27 2.44 0.50 23.23 1.16 1.51 1.68 1.86 2.03 2.32 2.50 1.00 23.73 1.19 1.54 1.72 1.90 2.08 2.37 2.55 1.50 24.23 1.21 1.57 1.76 1.94 2.12 2.42 2.60 2.00 24.73 1.24 1.61 1.79 1.98 2.16 2.47 2.66 2.50 25.23 1.26 1.64 1.83 2.02 2.21 2.52 2.71 3.00 25.73 1.29 1.67 1.87 2.06 2.25 2.57 2.77 3.50 26.23 1.31 1.70 1.90 2.10 2.30 2.62 2.82

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122 CHAPTER 9 CONCLUSIONS AND SUGGESTIONS FOR FU RTHER RESEARCH Arkin carambola is popular because of its sweetness and has potential to be harvested later than the 1 /4 yellow stage to exploit its natural sweetness. In this study Arkin carambola harvested at the 1/2 yellow color stage had a higher sugar to acid ratio (20.3) than when harvested at the 1/4 yellow stage (15.9). The fruit that was harvested when complete ly orange was attractive and had high sugar content; however, these fruit had high amounts of ethanol and norisoprenoids, which are aroma volatiles that indicate an over ripe flavor. Weight loss and color development were delayed and volatile production w as suppressed by storage at 5 oC and high humidity (85% to 95 %). The carnauba wax treatment also slowed weight loss. By limiting weight loss, stemend shriveling and fin margin browning were also slowed. However, the wax used in this test limited gas exchange and led to anoxic conditions inside the fruit, causing tissue browning and off flavors. The waxing treatment also prevented the outer fins from turning yellow during storage. Carambola fruit were only slightly responsive to ethylene. None of the ethyl ene treatments accelerated ripening sufficiently to promote a uniform appearance during storage and ripening, nor were compositional parameters affected. When exposed to 100 ppm ethylene for 48 h at 20 oC the epidermis of the fruit was slightly degreened, but surface pitting/ browning of the fruit increased during subsequent storage for 14 d at 5 oAqueous 1methylcyclopropene (1 MCP) treatment at 200 ug*L C. Fruit treated with 25 or 50 ppm did not have this response. Total volatiles increased, notably norisoprenoids that are associated with carotene degradation and over ripe flavors. 1 for 1 min maintained firmness in fruit harvested at 1/4, or 3/4 yellow as compared to untreated control fruit. It also extended shelf life by up to 3 d for fruit harvested at 1/4 and 1/2 yellow. The 1MCP treatment

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123 had no significant effect on the compositional parameters of the fruit, but did suppress total volatile production and prevented the outer edges of the fins from turning yellow. 1MCP treatments at lower concentrations (50 and 100 ug*L1) had similar affects on appearance but at lower magnitudes, and firmness was not significantly maintained over the untreated controls. Volatile production was also slightly suppressed. To attempt to accelerate ripening following 1 MCP treatment, fruit were treated with 200 ug*L1 aqueous 1 MCP, stored for 14 d at 5 oC then treated with ethylene (100 ppm at 20 oC for 24 or 48 h). Although the fins of the fruit were slightly degreened, surface pitting/browning and fin margin browning were exacerbated and fruit produced norisoprenoid aroma volatiles which are associated with carotene degradation over ripe flavor. The cost of adding a 1 MCP treatment was estimated over a large range (from $0.25 to $3.50 additional cost per box) and found to be feasible The retail price for individual fruit would be increased by less than $0.40 in most scenarios and could potentially be passed on to the consumer. Small increases in the retail prices of fresh produce are common and rarely change the dem and for a commodity. The aqueous 200 ug*L1 treatment concentration of 1 MCP was most successful when treating fruit harvested at the 1/2 yellow stage. Harvesting fruit in this stage yielded sweeter tasting fruit and the price sensitivity analysis showed it to be economically feasible. If fruit were to be harvested at the 1/2 yellow stage and treated with 1MCP they would last as long as nontreated fruit harvested at the 1/4 yellow stage and be just as firm. The eye catching appearance of the fruit can at tract customers and the sweet taste can convince them to purchase carambola again.

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124 More research is necessary to determine the effects of 1 MCP on firmness, particularly to determine the relationship between treatment and impact resilience. These results would give valuable insight into the feasibility of later harvests. Also, since 1 MCP affected firmness and the aroma profile, sensory analyses should be conducted to determine the effect of 1MCP on flavor and texture.

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125 APPENDIX OUTPUT FROM VOLATILE AN ALYSIS USING A GAS C HROMATOGRAM Figure A 1. Kovats retention index y = 0.0101x 3 0.7237x 2 + 39.28x + 322.23 R 2 = 0.9996 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 0 10 20 30 40 50 60 K o v a t s V a l u e Retention Time (m)

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126 A Figure A 2. Gas chromatograph of an initial sample harvested in the 1/4 yellow stage. A) Time 0 to 15 min; B) Time 15 to 30 min; C) Time 30 to 45 min; D) Time 45 to 60 min.

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127 B Figure A 2 Continued.

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128 C Figure A 2 Continued.

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129 D Figure A 2 Continued.

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130 LIST OF REFERENCES Acree, T. and A. Heinrich. 2008. Flavornet aroma descriptors DATU Inc. 3 November 2008. Gainesville, FL . Ali, Z.M., L.H. Chin, M. Marimuthu, and H. Lazan. 2004. Low temperature storage and modified atmosphere packaging of carambola fruit and their effects on ripening related texture changes, wall modification and chilling injury symptoms. Postha rvest Biology and Technology 33: 181192. Amir Shapira, D., E.E. Goldschmidt, and A. Altman. 1987. Chlorophyll catabolism in senescing plant tissues: In vivo breakdown intermediates suggest different degradative pathways for Citrus fruit and parsley leaves. Proc. Natl. Acad. Sci. 84: 1901 1905. Biale, J.B. and A.D. Shepherd. 1941. Respiration of citrus fruits in relation to metabolism of fungi. I. effects of emanations of ( penicillium digitarum sacc.) on lemons. American Journal of Botany. 28:4. Bre goli, A.M., et al. 2005. Postharvest 1methylcyclopropene application in ripening control of Stark Red Gold nectarines: Temperature dependant effects on ethylene production and biosynthetic gene expression, fruit quality, and polyamine levels. Postharve st Biology and Technology 37: 111121. Burg, S.P. and E.A. Burg. 1965. Ethylene action and the ripening of fruits: Ethylene influences the growth and development of plants and is the hormone which initiates fruit ripening. Science (New Series). 148(3674: 1190 1196. Campbell, C.A., D.J. Huber, and K.E. Koch. 1987. Postharvest response of carambolas to storage at low temperatures. Proc. Fla. State Hort. Soc. 100: 272275. Campbell, C.A., D.J. Huber, and K.E. Koch. 1989. Postharvest c hanges in s ugars, a cids, and c olor of c arambola f ruit at various t emperatures. HortScience 24(3): 472475. Campbell, C.A. and K.E. Koch. 1988. Sugar/acid c omposition and development of sweet and tart carambola. J. Amer. Soc. Hort. Sci. 114(3): 455457. Chin, L.H., Z.M. A li, and H. Lazan. 1999. Cell wall modifications, degrading enzymes and softening of carambola fruit during ripening. Journal of Experimental Botany 50(335): 767775. Choi, S.T. and D.J. Huber. 2008. Influence of aqueous 1methylcyclopropene concentratio n, immersion duration, and solution longevity on the postharvest ripening of breaker turning tomato (Solanum lycopersicum L.) fruit. Postharvest Biology and Technology 49: 147154.

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131 Choi, S.T., P. Trouvaltzis, C.I. Lim, and D.J. Huber. 2008. Suppression of ripening and induction of asynchronous ripening in tomato and avocado fruits subjected to complete or partial exposure to aqueous solutions of 1methylc yclopropene. Postharvest Biology and Technology 48: 206214. Crane, J.H., R.J. Campbell, and C.F Balerdi. 1993. Effect of hurricane Andrew on tropical fruit trees. Proc. Fla. State Hort. Soc. 106: 139144. Crane, J.H., C. Balerdi, R. Campbell, C. Campbell, and S. Goldweber. 1994. Managing fruit orchards to minimize hurricane damage. HortTechnolog y. 4(1):2127. Crane, J.H. 2007. Carambola Growing in the Florida Home Landscape. Fl. Coop. Ext. Serv. HS12. Degner, R.L., S.D. Moss, and J.H. Crane. 1997. Market development for the Florida tropical fruit industry. Fla. Agr. Mkt. Res. Ctr. Ind. Rpt. 972 Eaks, I.L. 1970. Respiratory r esponse, e thylene production, and r esponse to e thylene of c itrus f ruit during ontogeny Plant Phys. 45:334338 Forney, C.F., M.A. Jordan, K.U. Nichols, and J.R. DeEll. 2000. Volatile emissions and chlorophyll fluoresc ence as indicators of freezing injury in apple frui t. HortScience. 35(7)12831287. (abstr.). Gong, Y. and J.P. Mattheis. 2003. Effect of ethylene and 1Methylcyclopropene on chlorophyll catabolism of broccoli florets. Plant Growth Regulation. 40:3338. Hagenmaier, R.D. and R.A. Baker. 1993. Reduction in gas exchange of citrus fruit by wax coatings. J. Agric. Food Chem. 41: 283287. Hagenmaier, R.D. 2001. The flavor of mandarin hybrids with different coatings. Postharvest Biology and Technology. 24:7987. Hebert, P. J., J. D. Jarrell, and M. Mayfield, 1992: The deadliest, costliest, and most intense hurricane of this century (and other frequently requested facts). NOAA Technical Memorandum NWS NHC 31, National Oceanic and Atmospheric Administration, U.S. Department of Commerce, Washington, DC, 40 pp. Herderich, M., C. Neubert, P. Winterhalter, and P. Schreier. 1992. Identification of C13Norisoprenoid flavor precursors in starfruit (Averrhoa carambola L.). Flavour and Fragrance Jour nal 7: 179185. Jeong, J., D.J. Huber, and S.A. Sargent. 2003. Delay of avocado (Persea americana) fruit ripening by 1 methylcyclopropene and wax treatments. Postharvest Biology and Technology 28: 247257.

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132 Jiang, W., M. Zhang, J. He, and L. Zhou. 2004. Regulation of 1 MCP treaded banana fruit quality by exogenous ethylene and temperature. Food Sci. Tech. Int. 10(1): 00156. Kader, A.A. 2002. Postharvest technology of horticultural crops.3rd ed. University of California Agricultural and Natural Resources Communi cation Services, Oakland, C.A. Kahout, M.P. and J.H. Crane. 2004. The influence of within tree position on Arkin carambola ( Averrhoa carabola L.) fruit quality and number. Proc. Fla. State Hort. Soc. 117: 220223. Lee, Eunkyung. (2005). Quality chan ges induced by mechanical stress on Roma type tomato and potential alleviation by 1 methylcyclopropene Abstr. MS Thesis, University of Florida, 2005. Lam, P.F. and C.K. Wan. 1987. Ethylene and carbon dioxide production of starfruits (Averrhoa carambol a L.) stored at various temperatures and in different gas and relative humidity atmospheres. Trop. Agric. (Trinidad). 64(3): 181184. Li, J.T., B. Liao, C.Y. Lan, J.W. Qui, and W.S. Shu. 2007. Zinc, nickel and cadmium in carambolas marketed in Guangzhou and Hong Kong, China: Implication for human health. Sci. of the Total Environment. 388: 405412. Li, J.T., J.W. Qui, X.W. Wang, Y. Zhong, C.Y. Lan, and W.S. Shu. 2006. Cadmium contamination in orchard soils and fruit trees and its potential health risk in Guangzhou, China. Environmental Pollution. 143: 159165. Knight, J.R.and J.H. Crane. 2002. The Arkin Carambola in Florida. Proc. Fla. State Hort. Soc. 115: 9393. MacLeod, G. and J.A. Ames. 1990. Volatile components of starfruit. Phytochemistry. 29(1): 165172. Mahattanatawee, K., K.L. Goodner, and E.A. Baldwin. 2005. Volatile constituents and character impact compounds of selected Floridas tropical fruit. Proc. Fla. State Hort. Soc. 118: 414418. Mahattanatawee, K., J.A. Manthey, G. Luzio, S .T Talcott, K. Goodner, and E.A Baldwin. 2006. Total antioxidant activity and fiber content of select Florida grown tropical fruits. J of Agric. Food Chem. 54: 73557363. Martinez Romero, D., E. Dupille, F. Guillen, J.M. Valverde, M. Serrano, and D. Val ero. 2003. 1methylcyclopropene increases storability and shelf life in climacteric and nonclimacteric plums. J. Agric. Food Chem. 51: 46804686.

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133 Maul, E., S.A. Sargent, C.A. Sims, E.A. Baldwin, M.O. Balaban, and D.J. Huber. 2000. Tomato flavor and ar oma quality as affected by storage temperature. J. Food Sci. 65(7): 12281234. McDonald, R.E., T.G. McCollum, and E.A. Baldwin. 1996. Prestorage heat treatments influence free sterols and flavor volatiles of tomatoes stored at chilling temperature. J. Am er. Soc. Hort icultural Sciences 121(3): 531536 McLaughlin, E.W. 2004. The dynamics of fresh fruit and vegetable pricing in the supermarket channel. Preventative Medicine. 39(2):8187. Miller, W.R.and R.E. McDonald. 1993. Quality of coldtreated Arkin carambola coated with wax or plastic film. Proc. Fla. State Hort. Soc. 106: 234238. Miller, W.R. and R.E. McDonald. 1997. Carambola quality after ethylene and cold treatments and storage. HortScience. 32(5): 987899. Mitcham, E.J. and R.E. McDonal d. 1991. Characterization of the Ripening of Carambola (Averrhoa carambola L.) Fruit. Proc. Fla. State Hort. Soc. 104: 104108. Narain, N.B., H.J. Holschuh, and M.A. Vasconcelos. 2001. Physical and Chemical Composition of Carambola Fruit (Averrhoa caram bola L.) at Three Stages of Maturity. Cienc. Tecnol. Aliment. 3: 144148. Neto, M.M., F. Robl, and J.C. Netto. 1998. Intoxication by star fruit ( Averrhoa carambola) in six dialysis patients (Preliminary report). Nephrol. Dial. Transplant 13: 570572. Nu nez Elisea, R. and J.H. Crane. 2000. Selective pruning and crop removal increase early season fruit production of carambola (Averrhoa carambola L.). Scientia Horticulturae 86: 115126. Oslund, C.R. and T.L. Devenport. 1983. Ethylene and carbon dioxide in ripening fruit of Averrhoa carambola. HortScience. 18(2): 229230. Porat, R., W. Batia, C. Cohen, A. Daus, R. Goran, and S. Droby. 1999. Effects of ethylene and 1Methylcyclopropene on pH quality of shamouti oranges. Postharvest Biology and Technolo gy. 15:155163. Purvis, A.C. and C.R. Barmore. 1981. Involvement of ethylene in chlorophyll degradation in peel of citrus fruits. Plant Physiol. 68: 854856. Reid, M.S. 2002. Ethylene in postharvest technology, p. 149162 In: Postharvest technology or horticultural crops. 3rd ed. University of California Agricultural and Natural Resources Communication Services, Oakland, C.A.

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134 Rodrigo, M.J. and L. Zacarais. 2006. Effect of postharvest ethylene treatment on carotenoid accumulation and the expression of carotenoid biosynthetic genes in the flavedo of orange ( Citrus sinensis L. Osbeck) fruit Postharvest Biology and Technology. 43(1):1422. Roka, F. and R.D. Emerson. 2002. Demographics, income and choices: seasonal farm workers in southwest Florida, p.5766. In: J.L. Findeis, A.M. Vandeman, J.M. Larson, J.L. Rugan (eds.). The dynamics of hired farm labor: constraints and community responses. CABI Publishing, New York, NY. Rouseff, R. 2008. University of Florida, Citrus and Education Center. Color and Flavor Chemistry Group. 3 November 2008. Lake Alfred, FL. . Sargent, S.A. and J.K. Brecht. 1990. Carambola degreening study. Report to J.R. Brooks and Son, Inc. (Brooks Tropicals). Sa rgent, S.A., J.K. Brecht, and C.A. Campbell. 1994. Ethylene pretreatment allows early harvest of carambola. Manuscript for HortScience Sexton, R., Z. Mingxia, and J. Chalfant. 2003. Grocery retailer behavior in the procurement and sale of perishable fresh produce commodities. United States Department of Agriculture. Contractor and Cooperator report (2) Shui, G. and P.L. Leong. 2003. Analysis of polyphenolic antioxidants in star fruit using liquid chromatography and mass spectrometry. Journal of Chromat ography A. 1022: 6775. Siller Cepeda, J. D. Muy Rangel, M. Baez Sanudo, R. Garcia Estrada, and E. AraizaLizarde. 2004. Quality of carambola (Averrhoa carambola L.) fruits harvested at four stages of maturity. Serie Horticultura. 10(1): 2329 (Abstr.). Sisler, E. C., E. Dupille, and M. Serek. 1996 a. Effect of 1methylcyclopropene and methylenecyclopropane on ethylene binding and ethylene action on cut carnations. Plant Growth Regul. 18: 7986. Sisler, E.C., M. Serek, and E. Dupille. 1996 b. Comparis on of cyclopropene, 1methylcyclopropene and 3,3dimethylcyclopropene as ethylene antagonists in plants. Plan Growth Regul. 18: 169174. Sisler, E.C. and M. Serek. 1999. Compounds controlling the ethylene receptor. Bot. Bull. Acad. Sin. 40: 17. State of Florida. 2008. Costs and returns analysis Agricultural economics extension, Tropical Research and Education Center. 1 September 2008. Homestead, FL. < http://agecon trec.ifas.ufl.edu/CostandReturn.htm >

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135 State of Florida. 2008. Weekly market news price information for November 2008 as reported by USDA Agricultural economics extension, Tropical Research and Education Center. 4 December 2008 Homestead, FL. < http://agecontrec.ifas.ufl.edu/documents/marketprice/2008/carambolansep.pdf > State of Florida. 2008. Weekly market news price information for November 2008 as reported by USDA Agricultural economics extension, Tropical Research and Education Center. 4 December 2008 Homestead, FL. < http://agecontrec.ifas.ufl.edu/documents/marketprice/2008/carambolaoct.pdf > State of Florida. 2008. Weekly market news price information for November 2008 as reported by USDA Agricultural economics extension, Tropical Research and Education Center. 4 December 2008 Homestead, FL. Stone, H. and J.L Sidel. 1992. Sensory evaluation practices. 2 ed. San Diego: Academic Press, 336p. Teixeira, G.H.A. and J.F. Durigan, 2006. Controle do amadurecimento de carambolas com 1 mcp. Rev. Bras. Frutic., Jaboticabal SP. 28(3): 339342. Thomson, G., S. Winkler, and I. Wilkinson. 2003. Treatment of Asian vegetables and herbs with 1MCP. Rural Ind. Res. and Dev. Corporation Bul. 02/153. Tian, M.S., S. Prakash, H.J. Elgar, H. Young, D.M. Burmeister and G.S Ross. 2000. Responses of strawberry fruit to 1 m ethylcyclopropene (1MCP) and ethylene. Plant Growth Regulation. 32:8390. United States Department of Agriculture. 2008. Fruit and Vegetable Market News. 1 September 2008. Homestead, FL. < http://marketnews.usda.gov/portal/fv/ > United States Department of Agriculture. 2008. Food and Nutrition. 7 November 2008. Washington, D.C. < http://199.133.10.140/codesearchwebapp/(b0tk2eevusfrkv451mnnzebk)/measures.aspxi d=63109700/>. Weller, A., C.A. Sims, R.F. M atthews, and J.K. Brecht. 2006. Browning susceptibility and changes in composion during storage of carambola slices. J. of Food Sci. 62(2):256260. Wills, R.B.H. and V.V.V. Ku. 2002. Use of 1methylcyclopropene to extend the time to ripen of green tomatoes and postharvest life of ripe tomatoes. Postharvest Biology and Technology. 26:8590. Wolfe, K. 1999. Getting a food product to retail. Agricultural extension service. University of Tennessee. Knoxville. ADC Info40.

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137 BIOGRAPHICAL SKETCH Oren Warren was born in Sydney, Australia. He graduated cum laude from the University of Florida in 2006 w ith a Bachelor of Science degree in horticultural science and a minor in business administration. Oren continued his education at the University of Florida and was awarded his Master of Science degree in horticultural science with a minor in agribusiness i n May 2009.