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I ,3...» 1:3,... -63. .. , {.1 1...... .5554... 3.52.9.1». . ."u. at... 405..."? , .. 3 .. x 2.1.; :1...” s. 5:. .N. .K? .1 .26.; it'll... 719-55! Hit-.1954. is. 19!. .51.... :9 i All:l.l.l!. . lie)... .. {zittog a3).r\: 2...! .1 .0131"). . . .1512). ‘ it)? t. u 1 ha! .I: tvav .1: ’n 1 ii.‘ 11.5.. 9. , 2... .r t..- tch.:,. zit/3'. 3. 1 5.1.0.3! .w. I . . .97 THE}; IS a .. are) LIBRARY ‘5:- i§§?'£32£2 ml Pact J UDiVQia‘hy -w This is to certify that the thesis entitled MODIFIED ATMOSPHERE PACKAGING OF MANGO SLICES IN POLYMERIC FILMS presented by Sopacha Apichartvorasilp has been accepted towards fulfillment of the requirements for MASTER degree in PACKAGING fig [@{ZZ‘ , Major professor Date July 24, 2001 0-7639 MS U is an Affirmative Action/Equal Opportunity Institution PLACE IN RETURN Box to remove this checkout from your record. TO AVOID FINES return on or before date due. MAY BE RECALLED with earlier due date if requested. | DATE DUE DATE DUE DATE DUE 3 JULQI 22005: SEWW 343M 0 (“LI-"s 6/01 C‘JCIFICIDateDuopss-pjs f E, . ..._ _ _ 77V——— MODIFIED ATMOSPHERE PACKAGING OF MANGO SLICES IN POLYMERIC FILMS By Sopacha Apichartvorasilp A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE School of Packaging 2001 ABSTRACT MODIFIED ATMOSPHERE PACKAGING OF MANGO SLICES IN POLYMERIC FILMS BY Sopacha Apichartvorasilp Effects of washing treatments, storage temperatures and packaging on the quality of sliced mango were studied. Sliced mangoes were immersed in antibrowning solutions and observed for color change during storage at 5°C and 10°C. Washing with ascorbic acid (0.5%) inhibited enzymatic browning effectively over a 10-day storage period. Browning was more intense in mango slices stored at 10°C. Various concentrations of CaClz were investigated to maintain flesh firmness. No differences were observed in flesh firmness between mango slices treated with CaClz and control. Combinations of 0.5% ascorbic acid, packaging and modified atmosphere treatments were used to extend shelf life. Packaging in oriented polypropylene (OPP) bags resulted in higher headspace C02 and lower 02 concentrations than in other packaging films. Sliced mangoes packed in OPP with 5% Oz and 10% CO; at 5°C retained good visual quality for 13 days. Yeast and mold counts were performed at the end of storage. No mold was found and yeast populations were 2x102 CFU/g. The shelf life of mango slices was extended to 13 days using proper storage conditions. Mango should be carefully peeled, sliced, and treated with 0.5% ascorbic acid. Packaging in OPP bags initially flushed with 5% Oz and 10% C02, and stored at 5°C, gave the best results. ACKNOWLEDGEMENT I am indebted to Dr.Bruce Harte and Dr.Vanee Chonhenchob for their understanding, patience and kindness. Without their corporation, this research could not have been done. I thank Dr. Susan Selke and Dr.Jerry Cash, my committee, for their kindness and comment. Thanks also go to everyone in packaging Department of Kasetsart University for his/her help and warm welcome. I thank Jurmkwan Suemag and Viphop Tatiyamaneekul, for their unwavering friendship and encouragement. I thank Seree Anutarapom, for his tenderness and care. Finally, I thank my wonderful family, for their unconditional love and support. TABLE OF CONTENTS LIST OF TABLES .................................................................................................... v LIST OF FIGURES ................................................................................................. ix INTRODUCTION ..................................................................................................... 1 CHAPTER 1 LITERATURE REVIEW ............................................................................................. 3 CHAPTER 2 MATERIALS AND METHODS ................................................................................. 15 CHAPTER 3 RESULTS AND DISCUSSION ............................................................................... 24 CHAPTER 4 CONCLUSION AND FUTURE RESEARCHE ........................................................... 66 APPENDD( A ......................................................................................................... 69 APPENDIX B ......................................................................................................... 8O BIBLIOGRAPHY .................................................................................................... 95 LIST OF TABLES Table Page 1 Oxygen Transmission Rate (OTR) and Water Vapor 17 Transmission Rate (WVT R) of PP, OPP and LLDPE used to package sliced mangoes. 2 Effect of antibrowning agents on the light/dark (L) values of 26 mango slices stored at 5°C. 3 Effect of antibrowning agents on the light/dark (L) values of 28 mango slices stored at 10°C. 4 Effect of antibrowning agents on the green/red (“a”) values of 29 mango slices stored at 5°C. 5 Effect of antibrowning agents on the green/red (“a”) values of 31 mango slices stored at 10°C. 6 Effect of antibrowning agents on the yellow/blue (“b”) values of 33 mango slices stored at 5°C. 7 Effect of antibrowning agents on the yellow/blue (“b”) values of 34 mango slices stored at 10°C. 8 Effect of calcium chloride on the flesh firmness of mango slices 36 stored at 5°C. 9 Effect of calcium chloride on the flesh firmness of mango slices 36 stored at 10°C. 10 Analysis of Variance Procedure: the effect of antibrowning 70 treatments on ‘L’ values. 11 Analysis of Variance Procedure: the effect of antibrowning 7O treatments on ‘a’ values. 12 Analysis of Variance Procedure: the effect of antibrowning 71 treatments on ‘b’ values. 13 Analysis of Variance Procedure: the effect of CaClz treatments on 71 flesh firmness. 14 15 16 17 18 19 20 21 22 23 24 25 26 Analysis of Variance Procedure: the effect of each treatment and between treatments under modified atmospheric conditions to ‘L’ values. Analysis of Variance Procedure: the effect of each treatment and between treatments under modified atmospheric conditions to ‘a’ values. Analysis of Variance Procedure: the effect of each treatment and between treatments under modified atmospheric conditions to ‘b’ values. Analysis of Variance Procedure: the effect of each treatment and between treatments under modified atmospheric conditions to pH. Analysis of Variance Procedure: the effect of each treatment and between treatments under modified atmospheric conditions to weight loss. Analysis of Variance Procedure: the effect of each treatment and between treatments under modified atmospheric conditions to TSS. Analysis of Variance Procedure: the effect of each treatment and between treatments under modified atmospheric conditions to flesh firmness. Analysis of Variance Procedure: the effect of each treatment and between treatments under modified atmospheric conditions to PPO. Effect of antibrowning agents on ‘L’ values of mango slices stored at 5 and 10°C. Effect of antibrowning agents on ‘a’ values of mango slices stored at 5 and 10°C. Effect of antibrowning agents on ‘b’ values of mango slices stored at 5 and 10°C. Effect of calcium chloride on ‘L’ values of mango slices stored at 5 and 10°C. Effect of polymeric film type on ‘L’ value under modified atmosphere packaging. Mango slices were packed in PP, OPP, and LLDPE films and stored at 5°C. vi 72 73 74 75 76 77 78 79 81 82 83 84 85 27 28 29 30 31 32 33 34 35 36 37 38 Effect of polymeric film type on ‘L’ value under modified atmosphere packaging. Mango slices were packed in PP, OPP, and LLDPE films and stored at 10°C. Effect of polymeric film type on ‘a’ value under modified atmosphere packaging. Mango slices were packed in PP, OPP, and LLDPE films and stored at 5°C. Effect of polymeric film type on ‘a’ value under modified atmosphere packaging. Mango slices were packed in PP, OPP, and LLDPE films and stored at 10°C. Effect of polymeric film type on ‘b’ value under modified atmosphere packaging. Mango slices were packed in PP, OPP, and LLDPE films and stored at 5°C. Effect of polymeric film type on ‘b’ value under modified atmosphere packaging. Mango slices were packed in PP, OPP, and LLDPE films and stored at 10°C. Effect of modified atmosphere packaging on pH, of mango slices packed in PP, OPP, and LLDPE films and stored at 5°C. Effect of modified atmosphere packaging on pH, of mango slices packed in PP, OPP, and LLDPE films and stored at 10°C. Effect of modified atmosphere packaging on weight loss, of mango slices packed in PP, OPP, and LLDPE films and stored at 5°C. Effect of modified atmosphere packaging on weight loss, of mango slices packed in PP, OPP, and LLDPE films and stored at 10°C. Effect of modified atmosphere packaging on the T88, of mango slices packed in PP, OPP, and LLDPE films and stored at 5°C. Effect of modified atmosphere packaging on the T88, of mango slices packed in PP, OPP, and LLDPE films and stored at 10°C. Effect of modified atmosphere packaging on the firmness, of mango slices packed in PP, OPP, and LLDPE films and stored at 5°C. vii 85 86 86 87 87 88 88 89 89 90 90 91 39 4O 41 42 43 45 Effect of modified atmosphere packaging on the firmness, of mango slices packed in PP, OPP, and LLDPE films and stored at 10°C. Effect of modified atmosphere packaging on the PPO activity, of mango slices packed in PP, OPP, and LLDPE films and stored at 5°C. Effect of modified atmosphere packaging on the PPO activity, of mango slices were packed in PP, OPP, and LLDPE films and stored at 10°C. Changes in C02 concentration of mango slices packed in different packaging films stored at 5°C. Changes in CO; concentration of mango slices packed in different packaging films stored at 10°C. Changes in 02 concentration of mango slices packed in different packaging films stored at 5°C. Changes in 02 concentration of mango slices packed in different packaging films stored at 10°C. viii 91 92 92 93 93 94 Figure 10 11 12 LIST OF FIGURES Picture of Nam Dokmai at 90 days of age. The action of PFC on phenolic compounds. The action of PPO on tyrosine to produce indol-S, 6—quinone. Effect of antibrowning agents on the light/dark (L) values of mango slices stored at 5°C [3] and at 10°C [b]. Effect of antibrowning agents on the green/red (“a”) values of mango slices stored at 5°C [3] and at 10°C [b]. Effect of antibrowning agents on the yellow/blue (“D") values of mango slices stored at 5°C [a] and at 10°C [b]. Effect of calcium chloride on firmness of mango slices stored at 5°C [a] and at 10°C [b]. Changes in 02 concentration of mango slices packed in different packaging films in air [a], 5% CO2 and 5% 02 [b], and 10% CO2 and 5°/o 02 [C] at 5°C. Changes in 02 concentration of mango slices packed in different packaging films in air [a], 5% C02 and 5% 02 [b], and 10% CO2 and 5% 02 [c] at 10°C. Changes in C02 concentration of mango slices packed in different packaging films in air [a], 5% CO2 and 5% 02 [b], and 10% CO2 and 5% 02 [c] at 5°C. Changes in C02 concentration of mango slices packed in different packaging films in air [a], 5% CO2 and 5% 02 [b], and 10% C02 and 5% 02 [c] at 10°C. Effect of polymeric film type on ‘L’ value. Mango slices were packed in; [a] air, [b] 5% O2 and 5% C02, [c] 5% O2 and 10% C02 at 5°C. ix Page 27 30 32 35 38 39 41 43 13 14 15 16 17 18 19 20 21 22 23 24 Effect of polymeric film type on ‘L’ value. Mango slices were packed in; [a] air, [b] 5% O2 and 5% C02, [c] 5% O2 and 10% C02 at 10°C. Effect of polymeric film type on ‘a’ value. Mango slices were packed in; [a] air, [b] 5% O2 and 5% CO2, [c] 5% O2 and 10% C02 at 5°C. Effect of polymeric film type on ‘a’ value. Mango slices were packed in; [a] air, [b] 5% 02 and 5% C02, [c] 5% O2 and 10% C02 at 10°C. Effect of temperature on ‘L’ values of mangoes subjected to the following treatments; [a] citric acid, [b] ascorbic acid, [c] citric acid plus ascorbic acid, and [d] control. Effect of storage temperatures on ‘L’ value, of mango slices packed in PP film under modified atmosphere; [3] air, [b] 5% O2 and 5% CO2, [c] 5% O2 and 10% CO2. Effect of storage temperatures on ‘L’ value, of mango slices packed in OPP film under modified atmosphere; [a] air, [b] 5% O2 and 5% CO2, [c] 5% 02 and 10% CO2. Effect of storage temperatures on ‘L’ value, of mango slices packed in LLDPE film under modified atmosphere; [a] air, [b] 5% 02 and 5% C02, [c] 5% 02 and 10% CO2. Effect of MAP on ‘L’ values, of mango slices packed in; [a] PP, [b] OPP, [c] LLDPE at 5°C. Effect of MAP on ‘L’ values, of mango slices packed in; [a] PP, [b] OPP, [c] LLDPE at 10°C. Effect of MAP on ‘a’ values, of mango slices packed in; [a] PP, [b] OPP, [c] LLDPE at 10°C. Effect of MAP on %weight loss, mango slices were packed in; [a] air, [b] 5% O2 and 5% CO2, [c] 5% O2 and 10% CO2, and stored at 5°C. Effect of MAP on %weight loss, mango slices were packed in; [a] air, [b] 5% 02 and 5% CO2, [c] 5% 02 and 10% C02, and stored at 10°C. 45 46 48 49 50 51 53 54 55 57 58 25 26 27 28 29 Effect of MAP on the T55, of mango slices packed in; [a] air, [b] 5% 02 and 5% CO2, [c] 5% O2 and 10% C02, and stored at 5°C. Effect of MAP on the T55. Mango slices packed in; [a] air, [b] 5% 02 and 5% CO2, [c] 5% 02 and 10% C02, and stored at 10°C. Effect of MAP on the firmness, of mango slices packed in; [a] air, [b] 5% 02 and 5% C02, [c] 5% O2 and 10% C02, and stored at 10°C. Effect of MAP on the PPO activity, of mango slices packed in; [a] air, [b] 5% O2 and 5% C02, [c] 5% O2 and 10% C02, and stored at 5°C. Effect of MAP on the PPO activity, of mango slices packed in; [a] air, [b] 5% 02 and 5% C02, [c] 5% O2 and 10% C02, and stored at 10°C. xi 59 60 61 64 65 Introduction Thailand has great potential to export fresh vegetables, fruits, and flowers to many countries around the world. Mango fruits are considered to have significant economic value by the Thai government. Therefore, plantation research and promotion measures were sought and included in the sixth National Social and Economic Planning (1987-1991) proposal (Department of Agriculture promotion, 1990). The need for better postharvest storage, and export markets were emphasized in this report. Asian markets for mangoes include Malaysia, Hong Kong, Singapore, Japan, and Taiwan (Department of Agriculture promotion, 1990). The popular species of mango are Pimsane Dang, Raad, Thongdum and Nam Dokmai. Thailand is fundamentally an agricultural country. Surplus of produces are often left unattended to or not properly managed. This study is aimed at increasing chances of exports, maximizing value of farm produces, improving the strength of local economies and the economy of the country as a whole. Several problems limit the export quantities of ripe mangoes. The high cost of delivery by airfreight necessary due to its short shelf life is one limitation (Vetchachiva, 1976). Though shipment by sea is much cheaper, it takes a long time to arrive at the destination country. Storage of mangoes in refrigeration delays ripening, but will cause chilling injury to the fruits and, consequently, reduce the quality of the fruit (Thomas and Oke, 1983). Minimally processed fruit adds value to fresh produce. However, cutting, bruising or damaging the integrity of the plant tissue often allows enzymes and their substrates to come into contact, which causes enzymatic browning (Robert, 1994). Several approaches, including chemical treatments, edible coatings, and Modified Atmosphere Packaging (MAP), have been used to reduce this problem. Application of a 0.5% L-cysteine and 2% citric acid mixture effectively prevented browning of potatoes (Gunes and Lee, 1997). Dong and others (2000) reported that a shelf life of 15 to 30 days was achieved for sliced Anjou, Bartlett and Bose pears using a combination of 0.01% 4-hexylresorcinol, 0.5% ascorbic acid and 1.0% calcium lactate along with partial vacuum packaging. Mangoes are extremely sensitive to enzymatic browning. MAP is one method that can be used to decrease the rate of the browning reaction. Reduced O2 and elevated CO2 levels can extend storage shelf life of minimally processed fruit by controlling the respiration rate (Zagory and Kader, 1988). Herrnidal and others (1995) claimed a shelf life of 10 days at 5°C for shredded iceberg lettuce, using MAP. Lowering the temperature reduces respiration and delays senescence. Storage at 1°C resulted in better quality of pomegranates (Gil and others, 1996). The objective of this study was to determine the quality of mango slices stored under different modified atmospheric conditions in a variety of films. The influence of dipping treatments and storage temperatures on enzymatic browning was determined. CHAPTER 1 LITERATURE REVIEW Literature review Mango (Mangifera indica L.) is a tropical fruit, in the Anacardiaceae family, which originated in India and Burma (Mukherjee, 1967). It has become a fruit of significant economic value to many countries — Brazil, Pakistan, Mexico, Philippines, Thailand, Indonesia, Bangladesh, and Haiti, for example (Vangnai, 1986). Many varieties of mangoes are exported to countries around the world from Thailand; most are consumed when ripe. The main varieties are Pimsane Dang, Raad, Thongdum and Nam Dokmai. Mango trees reach 10-40 meters in height, with trunks of 10-40 cm. in diameter. Branches are widely and densely spread in all directions. The bark is a grayish brown. The trees have spear-shape leaves with a dark green glossy color on the upper side and a light green matte color on the opposite side. New leaves have a light to dark purple color. Flowers are panicle-like with scattered light yellow and sweet smell. The trees usually blossom during January to March and are ready for harvest between April and May (Smittinan, 1978). The Nam Dokmai variety normally needs 115 days from the bud stage to fully ripen (Dept. of Agricultural Technology, Thailand, 1988) and about 99 -111 days from the infancy of the fruit to fully ripen (Kasarntikul, 1983). It is a pear- shaped, juicy fruit with thin skin, a long flat seed, a light green color when it is unripe, with a rather sour taste. The fruit becomes yellowish when ripe, with a sweet-mild taste and fruity fragrance (Figure 1). Image in this thesis is presented in color. Its flesh is meaty but not pulpy (Dept. of Agricultural Technology, Thailand, 1988). Figure 1 Picture of Nam Dokmai at 90 days of age. The demand for minimally processed fruits and vegetables is growing rapidly due to its convenience and fresh-like quality. Two obstacles confront the extension of shelf life of fresh-cut fruit and vegetables. First, cutting, bruising or damaging the integrity of plant tissue triggers enzymatic browning (Figure 2). Second, destroying the natural protective layer encourages microbial proliferation. Phenolase, phenoloxidase, tyrosine, polyphenoloxidase and catecholase are common enzymes responsible for the initiation of enzymatic browning. Enzymatic browning can occur in the presence of active polyphenoloxidase, oxygen, and a suitable substrate. H H . 0 PFC OH PPO + O; O . :fl : E Browning z pigments R . R '5 Monophenpol Pblypheno'l . Orthoquinone Reducing agents (e. g., ascorbic acid) Figure 2 The action of PPO on phenolic compounds (Saper, 1993). Several ways to control this reaction include destroying the enzymes responsible for it and/or using reducing agents to convert o-quinones back to phenolic compounds. Common PPO substrates in plant tissues include the amino acid tyrosine and polyphenolic compounds such as catechin, caffeic acid, and chlorogenic acid. Tyrosine is a monophenol and is first hydroxylated to 3,4- dihydroxyphenylalanine (dopa) and then is oxidized to a quinone (Figure 3). P90 0“ m 0 . ~ e 2.- o 03 oz 5 N MW“ WWW ‘Tyrosine 3,4-dihydroxyphenylalanine Indol-5,6-qi1inone Figure 3 The action of PPO on tyrosine to produce indol-5, 6-quinone (Saper 1993) Control of enzymatic browning Many approaches have been used to combat enzymatic browning. Sulfites are excellent browning inhibitors. However, their application has been restricted by the FDA due to an allergic response in some asthmatics (Sapers, 1993). Ascorbic acid (vitamin C) is well known as an effective substitute for sulfites. It has the capability of reducing quinones back to phenolic compounds. A combination of dipping treatments has been used to control enzymatic browning. Sliced Anjou pears had browning-free color for 30 days by dipping the slices into a solution containing1.0% ascorbic acid, and 1.0% calcium lactate. A combination of 0.01% 4-hexylresorcinol (4-HR), 0.5% ascorbic and 1.0% calcium lactate can provide 15 to 30 days shelf life for Anjou, Barlett and Bosc pears (Dong et al, 2000). Sapers et al (1989) have claimed that ascorbic acid-2- phosphate and ascorbic—triphosphate inhibited enzymatic browning at out surfaces of raw apple but were ineffective in apple juice. Using L-cysteine as an inhibitor of pear PPO has been reported (Halim and Montgomery, 1978). Kojic acid was used as an inhibitor of PPO in the oxidation of 3,4- dihydroxyphenylalanine (dopa) (Chen and others, 1991). Sapers (1994) reported that a combination of sodium erythorbate, cysteine and EDTA at pH 5.5 was the most effective treatment controlling discoloration of minimally processed mushrooms. Temperature is a major factor controlling respiration, enzymatic activities, and growth of microorganisms. Shelf life of shredded lettuce was extended by low temperature storage (Bolin and others, 1977). Pigment degradation of minimally processed pomegranate seed was minimized by storage at 1°C (Gil and others, 1996). At low temperature (about 2°C) physiological activity and microbial growth were reduced sufficiently to delay spoilage of grated carrots (Carlin et al., 1990). The respiration rate usually decreases 6 to 8 times when temperature is lowered from 20 to 0°C (Robert, 1994). For tropical fruits and vegetables, very low temperature may cause chilling injury. For example, storage of bananas and mangoes below 10°C may induce chilling injury (Katesa, 1980). Temperature also has an effect on film permeability. As the temperature goes up, the permeability of the film increases. Each film responds to change in temperature differently. Therefore, a suitable film must be used in order to prolong the shelf life of minimally processed fruits and vegetables. Texture Texture loss and change in appearance are the most noticeable changes in fruits and vegetables during prolonged storage. These undesirable quality changes are accelerated by mechanical rupturing of the cells that occurs during cutting. The plant cell wall provides the mechanical support of the plant and individual plant parts. The physical structures of edible plant parts are due to a large extent to the presence of the cell wall (Stanley, 1991). Pectins are complex mixtures of polysaccharides that make up about one third of the cell wall. Pectin acts as an adhesive between cells, and contributes to the mechanical strength of the cell wall. Softening of the plant tissue is usually accompanied by changes in the properties of the pectin (Javis et al., 1988). In processing of fruits and vegetables, the natural protective layer is usually removed, which induces a high respiration rate and triggers accelerated texture deterioration (Rosen and Kader, 1989). Calcium salt has been reported to retard texture softening (Ponting and others, 1972). Calcium lactate increased the firmness of Bosc pear, compared to a control (Dong and others, 2000). Hedemi and Watada (1994) reported that calcium chloride has a significant effect on texture of shredded carrot. Calcium is not only associated with retaining texture but it is also said to reduce the respiration rate and ethylene production (Siddiqui and Bangerth, 1993). Carbon dioxide production was higher in untreated melon slices then in calcium treated (intact) fruit (Irene et al., 1999). Controlled/modified atmosphere packaging Controlled atmosphere packaging has been used to improve the shelf life of fresh fruits and vegetables. Reduced O2 and elevated CO2 reduce the respiration rate and delay maturation of fruits. A suitable range of O2 and 002 must be established for each commodity. Respiration may become anaerobic when the 02 level is too low or the CO2 level is too high. The shelf life of fresh ginseng roots was extended to 3 months under a controlled atmosphere ‘ "_ I I?!“ [- condition of 5% CO2 (Jeon and Lee, 1999). At a concentration of 6% 02, maturation of mushroom caps was reduced (Roy et al., 1995). Undesirable effects may develop in fruits and vegetables due to improper controlled atmosphere conditions. Knee and Hatfield (1981) reported that apples have been shown to lose flavor when 02 is too low. Concentration of 02 at 2% was optimum for reduction of maturation of mushrooms (Roy, 1995). Anaerobic respiration may result in off-flavors and aromas. Off-flavor development in broccoli packed in a low permeability film has been reported (Ballatyne et al., 1988). Controlled atmosphere packaging (CAP) is costly due to the need for precise control of the initial gas concentration. It is more appropriate for commodities that need extended shelf life, such as apples (Kader et al., 1989). As soon as the product is removed from CAP, the quality will begin to deteriorate. Favorable quality can be maintained in modified atmosphere packaging until the package is opened. Modified atmosphere packaging also requires a lower degree of control of the initial gas concentrations than CAP. 10 MA storage of fruits and vegetables in plastic bags, plastic film and/or wax coating at low temperature is widely practiced. However, problems with CO2 injury have resulted in changes in taste and smell due to fermentative deterioration. Selection of polymeric films of appropriate permeability that results in reduction of the respiration rate without inducing anaerobic respiration is a major aspect of modified atmosphere packaging. Pankasemsuk (1988) discovered an off odor after preserving “Kaewsaweii” mangoes in PE bags at 10°C for 12 days. Kongtao (1989) also encountered the same problem with “Raad” variety of mango, stored in PE bags at room temperature, 15°C and 10°C for 3, 14 and 17 days, respectively. Most commercial films are 4 to 5 times more permeable to CO2 than 02, which is helpful in developing a modified atmosphere package. Reduced O2 and elevated CO2 are attained through respiration of produce within a sealed package. Steady state conditions are achieved when consumption and diffusion of 02 are equal and production and diffusion of CO2 are equal. The shelf life of bananas packaged in polymeric films is doubled compared to that of bananas stored in air (Duan et al., 1973). A shelf life of 23 days for Nam Dokmai packed in polyethylene has been claimed by Koolpluksee (1991). Carlin et al (1990) reported that grated carrot was packed in films with very low oxygen permeability. This resulted in anaerobic respiration and loss of potassium. With highly permeable films, grated carrots had aerobic respiration and retained good quality. The firmness of kiwifruit slices stored under modified atmospheric conditions was higher than that of the control (Agar et al., 1999). 11 Chilling injury Chilling temperature can injure tropical fruits both before and after harvest, for example, banana, rambutan, and mango (Katesa, 1985); durian, mangosteen (Kosiyajinda, 1986); and pineapple (Paul and Rohrbach, 1985). The degree of injury varies with temperature and species. Severe damage is also likely when storing fruits in a chilling environment (Morris, 1982). Symptoms included damage to the skin, watery flesh, premature ripening, off flavor development and odor (Morris, 1982). Temperature, duration of storage, and fruit variety are the three main factors contributing to the level of injury (Katesa, 1985). Tropical fruits are more vulnerable to chilling injury (CI) than fruits from non-tropical countries (Katesa, 1985). Different varieties of fruits have different response to low temperature. Keeping mango under low temperature for a long time also increases the severity of Cl (Chaplin et al., 1986). Kensington mango and Common varieties are more vulnerable to Cl than Zil and Carrie when stored below 1°C for 15 days (Chaplin et al., 1986). Bramlage (1982) also found different types of CI in apples — “McIntosh” had a brown core, “Yellow Newtown” had an internal breakdown in texture, “Grimes Golden” had soft tissue, while “Jonathan” had soft scald. Other factors, in addition to low temperature, that affect chilling injury include amount of exposure to sunlight before harvest time; nitrogen, phosphorus and calcium concentration in the fruit; fatty acids in the membrane, and level of sugar in the tissue (Wang, 1982). 12 The appropriate temperature for storage of mango fruit (2-4 weeks) is approximately 12-13°C. Some varieties like “Keaw Sawaii” can be kept safely for 20 days at 10°C, “Nang Klangwan” for 28 days at 12°C, “Oakrong” for 20 days at 10°C, “Pimsen” and “Read” for 28 days at 9°C and “Thongdam” for 28 days at 9- 10°C (Katesa, 1988). Treating fruit and vegetables with chemical dips after harvest can reduce chilling injury. Dipping apricots into aqueous CaCl2 (Wade, 1981), “Valencia” orange into thiabendazole (T 32) (Wild and Hood, 1989), and waxing Marsh .mwl 1 A I w I grapes in a TBZ rich substance helped to reduce CI (Chalutz et al., 1985). 13 Microbial safety Minimally processed fruits and vegetables are very perishable. In most cases, they are more perishable than the raw materials; i.e. minimal processing often increases perishablility rather than making products more stable (Rolle and Chism, 1987). Improper handling can increase the population of microorganisms and can compromise quality and safety. Processing such as cutting and peeling can increase the population of microorganisms and shorten shelf life. Cleaning and washing reduces the numbers of microorganisms in most of the minimally processed fruits and vegetables. Chlorine has been used as a preservative dipping treatment (Robert, 1992). Commercially, 100-200 ppm is used as a sanitizer (Ji and Gross, 1998). Calcium and sodium hypochloride are widely used in the wash water for minimally processed fruits and vegetables (Robert, 1994) According to the Department of Medical Science (Thailand), ready-to-eat fruits and vegetables must not have populations exceeding; 1) yeast 104 CFU/g, mold 500 CFU/g, E.coli 10 CFU/g and Salmonella zero. 14 CHAPTER 2 MATERIALS AND METHODS 15 Materials and Methods Materials Mango. Mangoes (Mangifera indica L. cv. Nam Dokmai) were harvested by hand at the beginning of January, 2001 from a local (Charoen Pokapan) farm in the Ratchaburi province, Thailand and stored at room temperature (25°C) until needed. A sharp, stainless steel knife was used to peel and slice mangoes into eight pieces (approx. 120 g). Diseased and damaged slices were discarded. The knife was immersed in 100 ppm chlorine in water for 5 seconds between each slice in order to reduce cross-contamination. After peeling, sliced mangoes were immersed in 100 ppm chlorine for 20 seconds to reduce the microbial load on the fruit surface. Polymeric films. To study the influence of polymeric films on quality of mango slices, three different polymeric films with distinct oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) were used: 70 um linear low density polyethylene (LLDPE), 60 pm polypropylene (PP) and 80 pm oriented polypropylene (OPP) (Strong Pack company, Bangkok, Thailand). The characteristics of the films used are summarized in Table 1. 16 Table 1 Oxygen Transmission Rate (OTR) and Water Vapor Transmission Rate (WVT R) of PP, OPP and LLDPE used to package sliced mangoes. OTR WVTR (g.d“.m'2) Film (cm3.m'2.d" at 25°C) At 5°C At 10°C PP 2533 5.7 7.9 OPP 1474 5.7 7.5 LLDPE 3420 5.8 9.7 Oxygen Transmission Rate (OTR). The OTR of each film was measured using an 02 transmission rate (8500) machine. Film was cut into an octagonal shape. Grease was applied to the upper sealing surface and the lower cell O-ring. The test film was aligned on the sealing surface and then both halves clamped together using locating pin. Water Vapor Transmission Rate (WVT R). The WVTR was measured using ASTM standard E 96-93. Each film was cut into a 0.07 m diameter circle. Desciccant was placed in a 0.06 m diameter stainless steel circular dish, which was topped with the film. The edge of the film was sealed with hot wax and then the dish stored at 5 or 10°C. The dish was weighed every day for one week. A graph of time and weight was plotted and the slope was used to determine the WVTR. WVTR was caluated using the following equation: 1. WVTR = Slope (g/day) Surface area (m2) 17 Methods Effect of different antibrowning agents on pigment stability. To study the influence of antibrowning agents on pigmentation stability, four pieces (sliced) mangoes were dipped in the following solutions for 30 seconds: distilled water (control), 0.5% ascorbic acid, 1% citric acid (vlv), and 0.5% ascorbic acid plus 1% citric acid. They were then drained in a perforated plastic container and placed on foam trays stretch wrapped with high density polyethylene films, and stored at 5°C and 10°C until evaluated. Treated mangoes were removed randomly from trays to evaluate color change on day 0, 1, 2, 4, 7, and 10 or until the quality of mango slices was not acceptable. A Hunter Lab Ultrascan XE was used to study the change in color, using the codes L = light/dark, a = green/red and b = yellow/blue. Before analyses, the equipment was standardized with a standard white plate. Six measurements were taken randomly on the surface of each slice. Three replicates per treatment were performed. The most promising treatment was combined with MAP to prolong the shelf life of mango slices in later experiment. Effect of concentration of calcium chloride on flesh firmness To study the influence of calcium chloride concentration on flesh firmness, peeled mangoes were immersed in the following solutions for 30 seconds; water (control), 0.5, and 1% calcium chloride. They were then drained in a perforated plastic container and placed on foam trays stretch wrapped with high density polyethylene film, and stored at 5 or 10°C until analyzed. Treated mangoes were 18 removed randomly from trays to evaluate flesh firmness on day 0, 2, 3, 6, and 8. A Lloyd material testing machine equipped with 0.5 cm diameter cylinder stainless steel puncture head was used to measure the flesh firmness of the mango. The mango was cut into one cubic centimeter dices and place on a platform. Each dice was punctured 0.5 cm using the Lloyd material testing machine. The firmness was reported in Newtons. The most promising treatment was combined with MAP to prolong the shelf life of mango slices in the experiment to follow. Modified Atmosphere Packaging (MAP) of mango slices Respiration rate of mango slices The respiration rate of mangoes was measured using a closed system. Treated mangoes (250-300 g) were placed into gas-tight jars (6 L) and sealed. Two tubes were attached to the jar lids which were used as gas sampling ports. The jars were stored at 5 or 10°C. CO2 content was measured every hour using a gas chromatograph, Chrompack 9002GC, equipped with a thermal conductivity detector and Carboplot capillary column. Respiration rates were calculated using the following equation (Morales-Castro, 1992); 2. RR = ACxV th where RR is the respiration rate (mL'.kg"°h"); AC, the change in concentration of CO2 or 02; V, the free volume (mL) in the container; t, time (hr); and W, the weight (kg) of mangoes in the container. Respiration rate measurements were replicated three times. 19 Effect of MAP on the shelf life of mango slices To study the effect of different modified atmospheres on product shelf life, treated mango slices were prepared as previously described. Four treated mango slices were placed in trays and sealed in pouches of different polymeric materials. A Multivac packaging machine (A300) was used to seal the pouch containing the gases. Laboratory grade 02 and CO2 gases were obtained from Sitiporn gas company, Thailand. The gases were combined using the Multivac packaging machine (A300). The ratio of 02% to 002% was varied as follows: 5:5, 5:10 and air (control). N2 was used as a filler gas. Sealed packages were then stored at 5 and 10°C. Duplicate samples of each treatment were prepared. 02 and C02 concentrations were monitored on days 0, 1, 3, 6, 8, 10 and 13 using the Chrompack 9002 GC equipped with a thermal conductivity detector and a Carboplot capillary column (0.53mmx30m). Helium at (20cc/min) was used as the carrier gas. Gas samples were drawn from each package using a 25 pl gas tight syringe through self-sealing silicone and directly injected into the GC. Quality evaluation To evaluate the quality of mango slices, two packages of mango per treatment were chosen at random. Gas samples were withdrawn from the packages through a self-sealing silicone septum to determine headspace gas concentration. The packages were opened and the mango slices were weighed to determine weight loss. The slices were then used to evaluate color change, 20 Total Soluble Solid (T SS), pH, weight loss and Polyphenol oxidase (PPO) activity. All measurements were conducted on day 0, 1, 3, 6, 8, 10 and 13 except TSS, pH and % weight loss which were conducted on days 0, 3, 8 and 13 or until the quality was not acceptable Color. A Hunter Lab Ultrascan XE was used to study the change in surface color, where L = light/dark, a = green/red and b = yellow/blue. Prior to evaluation, the equipment was standardized with a standard white plate. Six measurements were taken randomly on the surface of each slice. Two replicates per treatment were evaluated. Total Soluble Solids (TSS). Mango slices were pushed through a small sieve stainless steel net in order to obtain juice. TSS measurement was conducted using a hand refractometer. 15 pl of mango juice was used. Two replicates per treatment were evaluated. pH. Mango juice was prepared as previously described. pH of the mango juice was measured using a pH meter (Mettler), Toledo, Ohio. Two replicates per treatment were evaluated. 21 Weight loss. To determine weight loss of the samples an analytical balance was used. The following formula was used to calculate % weight loss (wt/wt); 3. % weight loss (wet basis) = (Final weight(g) - lnitigl weight(g))x 100 Initial weight (9) Two replicates per treatment were used. Polyphenoloxidase (PPO) extraction and assay PPO extraction and assays were carried out according to Galeazzi (1981). Two replicates per treatment were evaluated. Twenty-five grams of treated mango slices were homogenized in a blender for 25 sec with 50 ml of a 0.2M sodium phosphate buffer, pH 7, containing 1% insoluble polyvinyl pyrrolidone (PVP) and 0.5% Triton X-100. The homogenates were centrifuged at 4°C for 15 min at 12,0006. The supernatant was stored at 5°C until assayed for polyphenoloxidase activity. 25 pl aliquots of the enzyme extracts, 2 ml 0.1 M catechol solution and 1 ml distilled water were mixed together and assayed for PPO at pH 6.5. The reference cuvette contained only catechol solution and distilled water. Enzyme activity was determined by measuring the rate of increase in absorbance at 420 nm at 25°C using a Perkin-Elmer Lamda 15 spectrophotometer. The slope of the initial rate of the reaction was used to determine the enzyme activity (U/min.ml). 22 Microbiological counts Yeast and mold counts were conducted at the end of storage on the most acceptable quality mango slices using the AOAC (1995) procedure. Ten grams of sample were added to 90 mL sterile water. Decimal dilutions of mango aliquots were made in tubes containing 9 mL sterile water. 0.1 mL of appropriate dilutions were deposited into sterile incubation plates and then 15 mL of FDA (Potato Dextrose Agar) poured onto each plate. The sample plates were then incubated at 37°C for 48 hours. Two replicates of each treatment were done. Ready-to-eat fruits and vegetables should have populations of no more than; 1) yeast 10‘ CFU/g, 2) mold 500 CFU/g, 3) E.coli 10 CFU/g and zero Salmonellae (Department of Medical Science, Thailand). Statistical analysis The effect of each treatment on quality characteristic was evaluated using ANOVA. A 3- or 4-way analysis of variance was conducted with storage time, temperature, type of film, and MAP as factors. To control type I error (the rejection of a true null hypothesis), a Fisher LSD multiple comparison test with p<0.05 was used to determine differences between treatments. 23 CHAPTER 3 RESULTS AND DICUSSION 24 Results and Discussion Effect of washing treatments on color deterioration “L” value. The effect of antibrowning agents on the light/dark (L) values of mango slices stored at 5°C is shown in Table 2. There were significant (p<0.05) effects on ‘L’ values. ‘L’ values dropped rapidly in all treatments except in mango slices treated with ascorbic acid. The brightness (L value) of mango slices treated with ascorbic acid decreased slowly in the first two-days and dropped rapidly after 4 days of storage (Figure 4a). Untreated mango slices (control) and mango slices treated with a combination of citric and ascorbic acid had lower L values than the other treatments. The citric acid solution produced the second best results, contrary to Gil et al. (1996) who reported that washing with citric acid gave no better results than washing with chlorine. Unacceptable L values were observed after 10—days storage with all treatments except ascorbic acid treated mangoes. Therefore, the most effective dipping treatment for mangoes (Nam Dokmai) was a 0.5% solution of ascorbic acid. This finding is in accordance with Ponting et al. (1972) who reported that ascorbic acid effectively inhibited browning on apple slices. Ascorbic acid has the capability of reducing quinones back to phenolic compounds. Combinations of ascorbic acid with an acidic polyphosphate were highly effective with both juice and cut apple surfaces. Gorny et al. (1998) reported that 2.0% ascorbic acid and 1.0% calcium chloride applied as a dipping treatment was effective in reducing surface browning of pears. 25 Table 2 Effect of antibrowning agents on the Iightldark (L) values of mango slices stored at 5°C. Washing treatmentc Day Citric“ Ascorbic” Plus” cm3 0 69.82 69.82 69.82 69.82 1 67.50 68.98 67.32 67.07 2 66.65 68.56 66.60 65.00 4 65.97 68.17 65.13 64.53 7 63.38 66.72 63.16 62.73 10 61.51 65.03 61.01 60.08 3’” Mean of three replicates; mean separation by Fisher LSD multiple comparison test (p<0.05); treatments in column followed by similar letters are not significant. Washing treatments: citric acid (1%); ascorbic (0.5%); plus — citric acid (1%) plus ascorbic acid (0.5%); ctrl - distilled water. Table 3 illustrates the effect of antibrowning agents on L value of mango slices stored at 10°C. Significant reductions of L values were observed after one-day storage in all treatments. Mango slices treated with citric and with ascorbic acid had higher L values than other treatments, as shown in Figure 4b. Acceptable L values were maintained for 7 days. After 7 days of storage, mango slices treated with ascorbic acid had the highest L value. Dong et al. (2000) reported that dipping Anjou pears in 1.0% Ascorbic acid and 1.0% calcium lactate enhanced browning free color for 30 days. Sapers et al. (1989) found that ascorbic acid-2- phosphate (AAP) and -triphosphate (AATP) inhibited enzymatic browning at the cut surfaces of raw apples but was ineffective in apple juice. 26 +Citric +Ascorbic +Plus +Ctrl [a] 'L‘ value 0 2 4 6 8 10 12 Time (days) [b] 'L’ value 0 2 4 6 8 1 0 Time (days) Figure 4 Effect of antibrowning agents on the light/dark (L) values of mango slices stored at SC [a] and at 10C [b] . 27 Table 3 Effect of antibrowning agents on the lightldark (L) values of sliced mangoes stored at 10°C. Washing treatmentc Day Citric“ Ascorbic“ Plus” CtrIb 0 69.82 69.82 69.82 69.82 1 66.67 68.31 64.24 64.62 2 65.42 66.48 62.46 62.12 4 63.32 65.34 60.25 60.34 7 61.24 63.61 58.53 58.00 3‘” Mean of three replicates; mean separation by Fisher LSD multiple comparison test (p<0.05); treatments in columns followed by similar letters are not significantly different. ° Washing treatments: citric acid (1%); ascorbic (0.5%); plus — citric acid (1%) plus ascorbic acid (0.5%); ctrl - distilled water. “a” value. "a” value signifies color, “a” value varies from green to red. Effect of antibrowning agents on “a” values of mango slices stored at 5°C are shown in Table 4. No significant treatment effects were found among mango slices treated with citric, ascorbic acid, or control. An increase in "a” values for all treatments, after oneday storage occurred (Figure 5a). After 2—days storage, the “a” value decreased slightly. It remained almost stable for the remaining storage time. The effect of antibrowning agents on “a" values of mango slices stored at 10°C is shown in Table 5. No significant treatment effects were found between mango slices treated with citric and ascorbic acid. Figure 5b illustrates the effect 28 of antibrowning agents on “a” values of mango slices stored at 10°C. “a” values increased in all treatments except the control during 7-day storage. Table 4 Effect of antibrowning agents on the green/red (“a”) values of sliced mangoes stored at 5°C. Washinitreatment“ Day Citirica‘ Ascorbic“ Plus” cm“ 0 5.02 5.02 5.02 5.02 1 5.41 7.14 7.74 5.79 2 6.38 5.11 6.87 6.68 4 5.54 5.73 5.51 6.87 7 5.00 5.13 7.07 5.49 10 5.74 5.55 7.03 5.74 8’” Mean of three replicates; mean separation by Fisher LSD multiple comparison test (p<0.05); treatments in rows followed by similar letters are not significantly different. Washing treatments: citric acid (1%); ascorbic (0.5%); plus — citric acid (1%) plus ascorbic acid (0.5%); ctrl - distilled water. 29 [-0- Citric +Ascorbic +Plus —x—CtrII 9 8 7 3 2 E 4 [a] 39 3 2 1 0 0 2 4 6 8 10 12 Time (days) 9 8 7 m 6 2 5 .g 4 [b] 50 3 2 1 0 0 2 4 6 8 Time (days) Figure 5 Effect of antibrowning agents on the greenlred ('a') values of mango slices stored at 5C [a] and at 100 [b]. 30 Table 5 Effect of Antibrowning agents on the green/red (“a”) values of sliced mangoes stored at 10°C. Washing treatmentc Day Citric“ Ascorbic“ Plus” cm" 0 5.02 5.02 5.02 5.02 1 5.51 5.27 7.00 5.35 2 5.53 5.90 7.14 5.47 4 5.45 5.28 5.85 5.35 7 5.82 7.55 7.90 7.44 3'” Mean of three replicates; mean separation by Fisher LSD multiple comparison test (p<0.05); treatments in columns followed by similar letters are not significantly different. plus ascorbic acid (0.5%); ctrl - distilled water. “b” value. “b” value signifies color, “b” value varies from yellow to blue. Effect of antibrowning agents on “b” values at 5 and 10°C are shown in Table 6 and 7, respectively. No significant treatment effects were found between mango slices treated with citric and ascorbic acid. As shown in Figure 6, “b” values decreased slightly during storage. 31 Washing treatments: citric acid (1%); ascorbic (0.5%); plus - citric acid (1%) { [+Citric +Ascorbic +Plus —x-Ctrll . 30 l 25 5W ' a, 20 .22 f)“ 15 [a] 9 10 0 2 4 6 8 10 12 Time (days) I l i m 20 2 g 15 In [D] 10 — 5 O I f I 0 2 4 6 8 Time (days) L u Figure 6 Effect of antibrowning agents on the yellow/blue ('b’) values of mango slices stored at 5C [a] and at 10C [b]. 32 Table 6 Effect of antibrowning agents on the yellow/blue (“b”) values of mango slices stored at 5°C. Washingtreatmentc Day Citric” Ascorbic“ Plusa Ctrl" 0 26.20 26.20 26.20 26.20 1 25.10 25.89 25.58 26.04 2 25.21 24.90 23.98 26.08 4 24.76 24.41 21.70 25.16 7 23.36 24.58 23.06 24.45 10 22.33 22.94 20.58 25.57 3‘” Mean of three replicates; mean separation by Fisher LSD multiple comparison test (p<0.05); treatments in columns followed by similar letters are not significantly different. ° Washing treatments: citric acid (1 %); ascorbic (0.5%); plus — citric acid (1%) plus ascorbic acid (0.5%); ctrl - distilled water. 33 Table 7 mango slices stored at 10°C. Effect of Antibrowning agents on the yellowlblue (“b”) values of Washing treatment" Day Citric“ Ascorbic“ Plus“c Ctrid 0 25.20 25.20 25.20 25.20 1 25.07 23.24 22.95 24.98 2 24.74 23.29 22.72 24.92 4 23.35 22.22 21.27 24.12 7 22.57 23.70 21.74 22.91 a'° Mean of three replicates; mean separation by Fisher LSD multiple comparison test (p<0.05); treatments in columns followed by similar letters are not significantly different. plus ascorbic acid (0.5%); ctrl - distilled water. Effect of calcium chloride on flesh firmness No significant treatment effects were found in any of the treatments (Table 8 and 9). Flesh firmness dropped rapidly after 2 days storage for all treatments and then stabilized as shown in Figure 7. At the end of storage, flesh firmness of 2.068 - 2.783N was obtained. 34 Washing treatments: citric acid (1 %); ascorbic (0.5%); plus - citric acid (1 %) [-2- Ctrl +05% CaCI2 +10% CaCl2 9 8 A 7 a 5 [a] r: 4 E 3 LL 2 1 0 0 2 4 5 8 10 Time (days) 9 8 7 g 5 (I) 8 5 lb] c 4 E E 3 2 1 0 0 2 4 5 8 10 Time (days) Figure 7 Effect of calcium chloride on firmness of mango slices stored at 56 [a] and 100 [b]. 35 Table 8 Effect of calcium chloride on the flesh firmness of mango slices stored at 5°C Firrnness (N) "8 Dav Ctrl CaCl20.5% CaCl21.0% 0 7.753 7.753 7.753 2 3.215 3.279 3.659 3 2.710 3.166 3.538 6 2.605 3.207 2.933 8 2.255 2.406 2.783 ”3 No significant different at p < 0.05 by Fisher LSD multiple comparison test. Table 9 Effect of calcium chloride on the flesh firmness of mango slices stored at 5°C Firrnness (N) "S Day Ctrl CaCl2 0.5% CaCl2 1.0% 0 7.753 7.753 7.753 2 3.205 3.167 3.212 3 2.640 3.244 3.394 6 2.362 2.409 2.349 8 2.516 2.068 2.533 ”S No significant different at p < 0.05 by Fisher LSD multiple comparison test Effect of polymeric films under modified atmosphere packaging Ascorbic acid was found to be the most effective treatment to inhibit enzymatic browning. Therefore, it was applied as a dipping solution prior to evaluating the effect of polymeric film type. Three polymeric films were Chosen: (1) Polypropylene (PP), (2) Oriented polypropylene (OPP), and Linear Low density polyethylene (LLDPE). Respiration rates of mango slices stored at 5 and 36 10°C were 67.5 and 69.9 mlCO2.h".kg", respectively. Changes in 02 concentration in PP, OPP and LLDPE packs of mangoes are shown in Figure 8 and 9. Concentration of O2 gradually decreased in all control packages (air) at 5 and 10°C as shown in Figure 8a and 9a. 02 concentrations for treatments which started with 5% O2 in the headspace varied. After 3 days, the amount of oxygen declined at both temperatures. All packages packed in air reached steady state during 6- and 10—days storage at 10 and 5°C, respectively. Steady state was not achieved in packages starting with 5% O2 and 5% CO2. OPP bags which contained10%CO2 initially reached steady state after 1- and 6- days at 10 and 5°C, respectively. On the other hand, steady state was not achieved in LLDPE and PP bags initially flushed with 10% CO2 and 5% 02. The difference in 02 concentration can be explained by the difference in 02 permeability through the films. The lowest 02 concentrations were found in packs of the least permeable films and vice-versa. For example, the 02 concentration of mango slices packed in PP was lower than the 02 concentration of mango slices packed in LLDPE (Figure 9b). Changes in CO2 concentrations in PP, OPP and LLDPE packs are shown in Figure 10 and 11. Equilibrium values for CO2 were found only in LLDPE bags. The highest concentration of CO2 was a result of the lowest film permeability. The permeability of film depends on its degree of crystallinity and mobility between polymeric chains. For example, the concentration of CO2 in OPP bags was highest in MA treatments, which is a result of an increasing in crystallinity. C02 has been reported to inhibit some reactions in the Krebs cycle through 37 + LLDPE + PP +oPPl %02 concentration 0 5 10 15 Time (days) Figure 8 Time (days) c 10 .2 8 f 6 t 4 8 (5' 2 35 0 0 5 10 15 Time(days) :10 . 4 'g 8 _ A I. g / w’ c 6 g V 8 4 0: 2 °\ 0 i I T— *T”———‘I_"~_' 0 2 4 6 8 10 12 14 [8] [b] [0] Changes in 02 concentration of mango slices packed In different packaging films in air [a] , 5% CO2 and 5% 02 [b] , and 10% CO2 and 5% 02 [c] at 5C 38 l—o—LLDPE +PP +oPP] c 25 —————*— g 20 #7 g g 15 \ C a ; c5” 5 “T“ ‘ i °\° 0 ‘L—’ — __ r a r r 0 2 4 5 8 10 i Time (days) " 12 C g 10 E 8 9:3 5 8 4 lb] CS” 2 o\° 0 0 2 4 6 8 10 Time (days) 12 .§10 E . a 3 “ l 964 ———9 E; 4 ' [C] 5322 0 f 7 T f 0 2 4 6 8 10 Time (days) Figure 9 Changes In 02 concentration of mango slices packed In different packaging films in air [a], 5% CO2 and 5% 02 [b], and 10% C02 and 5% 02 [c] at 10C 39 inactivation of some enzymes (Kader, 1986). CO2 may inhibit PPO activity (Murr and Morris, 1994). Mango slices in OPP bags containing 5% O2 and 10% CO2 had an acceptable visual quality (high ‘L’ value) after 13- and 8-day storage at 5 and 10°C, respectively, as shown in Figure 12 and 13. ‘a’ values dropped significantly after 1 day storage and increased slightly afterward as shown in Figure 14 and 15. ‘b’ values decreased slightly during storage for all treatments. No significant treatment effect was found for ‘b’ values. Similar results were reported by Gil et al. (1996), who showed that OPP bags were suitable for maintaining the pigment color of pomegranate seeds. Mango slices in LLDPE bags had more browning than those in PP and OPP bags. Koolpluksee (1991) reported that storage of mangoes in PP bags had a shelf life of 23 days. Effect of low temperature storage To study the effect of low temperature storage, 5 and 10°C samples were divided into two parts i.e., effect of low temperature storage on mango slices treated with antibrowning agents, and effect of low temperature storage on mango slices packed in polymeric films under modified atmosphere conditions. Effect of low temperature storage on mango slices treated with antibrowning agents There were significant differences (p<0.05) in ‘L’ and ‘b’ values between the two different temperatures. At 5°C, no microbial growth was visually present 40 I—O—LLDPE +PP +oPPl C .3 .8 C 8 C 8 c5“ 0 s“ 0 2 4 5 8 1o 12 14 Time(days) C .3 g C 8 C 8 c5“ 0 s“ 0 2 4 5 8 1o 12 14 Time(days) __ A 15, § 14 E12 =10 9 5 8 5 c5“ 4 :3 2 0 0 2 4 5 8 10 12 14 Time(days) [a] lb] [0] Figure 10 Changes In CO, concentration of mango slices packed In different packaging films In air [a], 5% C02 and 5% 02 [b]. and 10% CO, and 5% 02 [c] at 5C 41 +LLDPE +PP +OPP c 14 .9 *9: 12 ‘E 10 § 8 6 [a] 9:. 4 8 2 o\° 0 0 2 4 6 8 10 Time (days) C .9 ‘9 E t lb] 8 <5“ 0 a2 0 2 4 6 8 10 Time (days) c 14 2% 12 .3 10 8 8 § 6 [CI ‘2’ 32 0 0 2 4 6 8 10 Time (days) Figure 11 Changes In CO, concentration of mango slices packed In different packaging films In air [a], 5% CO2 and 5% 02 [b], and 10% CO2 and 5% 02 [c] at 10C 42 i Fo— PP + OPP + LLDPE] [a] 50 f r r r r 0 2 4 6 8 10 12 14 Time (days) P 70 65 - 0 .2 g 60 \k ‘ '_, - a. 50 T TI r T I r 0 2 4 6 8 10 12 14 L Time (days) 70 65 Q) .3. f; 60 “A [c] :-J 55 50 T I I I If I 0 2 4 6 8 10 12 14 Time (days) Figure 12 Effect of polymeric film type on the lightldark (L) value. Mango slices were packed In; [a] air, [b] 5% O2 and 5% C02, [c] 5%02 and 10%CO2 at 5C 43 I+ PP + OPP + LLDPE] 'L’ value 10 Time (days) 70 65 — o 2 \— Z-I 55 — 50 I f f j 0 2 4 6 8 10 Time (days) 70 65 — o 2 g 50 \ I—I 55 .. _ __ __,_ __ __ ____ I 50 fl r r T 0 2 4 6 8 10 Time (days) [b] [C] Figure 13 Effect of polymeric film type on the lightldark (L) value. Mango slices were packed In; [a] air, [b] 5% 02 and 5% CO2, [c] 5%02 and 10%CO2 at 1°C b—PP +oPP +LLDPE 6 5 g 4 g 3 35 2 1 0 0 2 4 6 8 10 12 14 Time (days) 6 5 A 3 4 ‘ 9 3~ 3° 2 - 1 \Z 0 I l I T T f 0 2 4 6 8 10 12 14 Time (days) ‘a’ value I} a T Time (days) [a] [bi [C] Figure 14 Effect of polymeric film type on the green/red (‘a') value. Mango slices were packed In;[a] air, [b] 5% O2 and 5% CO2, [51 5%02 and 10%002 at 5C 45 b—PP +oPP +LLDPE] 7 6 g 5 a 4 > 3 2w 2 1 . 0 i . A t 0 2 4 6 8 10 Time (days) 7 1"“ —- 6 g 5 a 4 .> 3 .m 2 1 0 0 2 4 6 8 10 Time (days) 7 f 6 g 5 To 4 ? 3 .‘u 2 1 0 0 2 4 6 8 10 Time (days) [a] [b] [C] Figure 15 Effect of polymeric film type on the greenlred (’a’) value. Mango slices were packed in; [a] air, [b] 5% 02 and 5% CO2, [c] 5%02 and 10%C02 at 100 46 in any of the packs. The ‘L’ values of all mangoes were superior to the L values of mango slices stored at 10°C (Figure 16). At 10°C, the quality of all packs was unacceptable, untreated mango slices (control) were spoiled In 7 days. After 10 days, mango slices treated with ascorbic acid and stored at 5°C were satisfactory. Effect of low temperature storage on mango slices packed in polymeric films under modified atmosphere packaging Polypropylene (PP), Oriented polypropylene (OPP) and Linear Low density polyethylene (LLDPE) films were used to packaged to package the mangoes. Significant treatment effects (p<0.05) occured for ‘L’, ‘a’, and ‘b’ values. Changes in ‘L’, ‘a’, and ‘b’ values in PP, OPP and PE packages at 5 and 10°C are shown in Figures 17, 18 and 19. Mango slices stored at 5°C exhibited a high ‘L’ value at the end of 13 days storage, while mangoes stored at 10°C had an acceptable visual quality for only 8 days. Carlin et al. (1990), was able to maintain grated carrots in an acceptable quality in low temperature storage, even with a low permeability film. BoIin et al. (1977) found that the shelf life of shredded lettuce was extended under low temperature storage. Pigment degradation of minimally processed pomegranate seed was minimized by storage at 1°C (Gil et al., 1996). Enzyme activities and biochemical changes are temperature dependent. Therefore, optimal temperature minimizes tissue senescence and thus delays enzymatic discoloration. 47 .23 53.653 E .23 55.5 E "8:258: 9.36:8 55 8 “.8333 359.2: .5 .32.; A... eta—5:2. 55 co 8383:.8 Co «germ or 5.59”. 53:3 E .23 53.3.5.5 «:3 Bow 2.25 E $.33 08:. 353 08F N. 2 m o v N o N. 2 m m 5 N o 8F MM A p h M r 8 on Co /r / 3 M... /O/ m a W i// 8 a f/ 8 a E 8 404 8 2 2. NA NN 1'2 5.53 9:: 553 as: N. N. 2 m o v N o » _ L P _ mm 02 B 8 - on I all No - «I. 1.. m / - 8 m - 8 E 3 NA 48 \ \ [a] Date (day) a: 2 .9 [b] __1 10C 55 50 I I f if I 77 0 2 4 6 8 10 12 14 Date (day) 70 1k 65 - - g \' W“ 5.C a 50 > c 9 10C I I 55 50 I I I I I I Date (day) Figure 17 Effect of storage temperatures on ‘the lightldark (L) value, of mango slices packed in PP film under modified atmosphere; [a] air, [b] 5% O2 and 5% CO2, [C] 5%02 and 10%602 49 10C [a] [b] Time (days) 70 65 R - 5C- o v a 2 (U 60 .... > c :_, 10C [ l 55 ~— —~ ——— — — 50 —r— T r : r r 0 2 4 6 8 10 12 14 Time (days) Figure 18 Effect of storage temperatures on the lightldark (L) value, of mango slices packed In OPP film under modified atmosphere; [a] air, [b] 5% 02 and 5% CO2, [c] 5%02 and 10%C02. 50 ’L‘ value 55 \- 10C 50 I T T I f I 0 2 4 6 8 10 12 14 Time (days) A l l 65 g \\ C E 50 W - 5 9 v 4 55 10C 50 I r r r f r 0 2 4 6 8 10 12 14 Time (days) 70 0 65 - 2 5C g 60 \- H '_r ' 55 2_ 10C 50 f fir F Tr I I 0 2 4 6 8 10 12 14 Time (days) [a] [b] [C] Figure 19 Effect of storage temperatures on the lightldark (L) value, of mango slices packed In LLDPE film under modified atmosphere; [a] air, [b] 5% O2 and 5% CO2, [c] 5%02 and 10%002 51 Effect of MAP on product quality Color. Figures 20 and 21 show the effect of MAP on ‘L’ values of mango slices stored at 5 and 10°C, respectively. Gas concentration had a significant effect on ‘L’ values. ‘L’ values dropped significantly after 2 days storage at 5°C. Mango slices packaged in air were browner than mango slices packed in the other atmospheres. Acceptable visual quality was obtained In mango slices packed in 5% O2 and 10% 002 at both temperatures. At 5°C no significant treatment effects were found on “a” value. The effect of MAP on the ‘a’ values of mango slices stored at 10°C are shown in Figure 22. ‘a’ values dropped after 1-day storage and then gradually increased in all treatments. Gas concentration had a significant effect on ‘a’ values. The highest ‘a’ values were obtained in mango slices packed in air. No significant treatment effects on ‘b’ values were found. ‘b’ values changed only slightly during storage. pH. Gas content had no significant treatment effects (p<0.05) on pH of the mangoes at 5 and 10°C. This was in contrast to the findings of Siripanich and Kader (1986), who reported that lettuce stored at 0°C in16% CO2 and in air had a decreased pH. 52 [+Air +5%c02 +1ocozl 70 c 55 5% 2 re 60 L): \o [a] ‘ 55 50 I I I T I I 0 2 4 6 8 10 12 14 Time (days) [+Air +5%002 +10002 I 70 g 65 W T; 50 \. [bl =‘ 55 50 I I I I I fir 0 2 4 6 8 10 12 14 Time (days) +Air +5%CO2 Nit-10002] 70 g 65 7 7;? 50 [CI =‘ 55 50 I I 7 j— I I 0 2 4 6 8 10 12 14 Time (days) Figure 20 Effect of MAP on the lightldark (L) values, of mango slices packed In, [a] PP, [b] OPP, and [c] LLDPE at 50 53 +Air +5%COZ +10002j 70 Q) 65 — N 2 g 50 =‘ 55 50 I a , — e 4 0 2 4 6 8 10 Time (days) I—o—Air +5%coz +1ocozj Q) 2 (U > I-1 50 i i r i 0 2 4 6 8 10 Time (days) [+Air +5%COZ +1OCOZI 0 2 (U > i y Time (days) Figure 21 Effect of MAP on the lightldark (L) values, of mango slices packed in, [a] PP, [b] OPP, and [c] LLDPE at 106 54 [a] [b] [+Air +5002 +1ocozl 8 ! 5 [a a: 2,, W [a] :m 2 i 0 T Y i f 5 O 2 4 6 8 10 . Time (days) +Air -I- 5002 -Ar- 10002 8 ._-__ __..._ _- s [b] 'a' value Time (days) +Air +5c02 +10002] 3 a [C] > 35 0 i T T l O 2 4 6 8 1 0 Time (days) Figure 22 Effect of MAP on the greenlred ('a') values, of mango slices packed in; [a] PP, [b] OPP, [c] LLDPE at 1°C 55 Weight loss. Figure 23 and 24 show the effect of MAP on weight loss of mango slices stored at 5 and 10°C, respectively. Weight loss occurs due to moisture loss by diffusion through the film. Little weight loss occurred in mango slices packed in low water vapor transmission rate (WVT R) films. Total Soluble Solids (TSS). The longer mango is stored, the higher will be its TSS. This is because starch in the mango fruit is converted into sugar (Arpaia et al., 1985). However, elevated amounts of C02 and lower levels of 02 will delay its ripening (Katesa, 1985) and, thus, delay the increase in T88. Packages that initially had 10% CO; in the headspace had lower TSS compared to other treatments. The same result was reported with the “Alphonso” variety (Lakshminarayanas and Subramanyam, 1970). At 5°C, the highest TSS was obtained after 8-day storage (except mango slices packed in air) with a gradual declined (Figure 25). At 10°C, TSS increased rapidly in all treatments after 3—days storage and then gradually declined (Figure 26). Mangoes packaged in PE film had the highest TSS. Firrnness. No significant treatment effects were found in mango slices stored at 5°C. Figure 27 shows the effect of MAP on the firmness of mango slices stored at 10°C. Flesh firmness dropped significantly after 3-days storage. Mango slices 56 F.— PP +OPP + LLDPE] 0.8 0.6 [a] 0.4 -~——— 0.2 0 /I I I fl fit I 14 2 4 6 8 10 12 Time (days) %Weight loss 0.8 [a 0.6 0.2 o /T T I I T I 12 14 0 2 4 6 8 10 Time (days) % Weight loss [Cl %Weight loss Time (days) Figure 23 Effect of MAP on %welght loss, mango slices were packed in, [a] air, [b] 5% 02 and 10% 002, [c] 5% O, and 10% CO, stored at SC 57 i +PP +OPP +LLDPE 1 (D 3 0.8 33': o . go 0.2 o\ O 0 2 4 6 8 10 {— Time (days) 1 8 0.8 2 L— g 0.6 5 —~— [b] 'as 0.4 03° 0.2 M o / f j i 0 2 4 6 8 10 Time (days) i 1 8 2 is; 'as [C] 3. °\ 0 i l ‘1' T 0 2 4 6 8 10 Time (days) Figure 24 Effect of MAP on %weight loss, mango slices were packed in, [a] air, [b] 5% O, and 10% C02, [c] 5% O, and 10% CO; stored at 1°C 58 [-5- PP +OPP +LLDPEj 17.5 17.0 ‘19 15.0 15.5 15.0 o 2 4 5 8 1o 12 14 Date (days) 17.5 17.0 4 A i a, 16.5 ('2 16.0 / \ [bl 15.5843//'\!—I 15.0 I I If I I T o 2 4 6 8 1o 12 14 Date (days) 17.5 /\ 17.0 V, 16.5 W i2 _ \ [c] 16.0 \- 15.5 —7 15.0I I I I I I o 2 4 6 8 10 12 14 Date (days) Figure 25 Effect of MAP the on T88, of mango slices packed in; [a] air, [b] 5% Oz and 10% 002, [c] 5% O, and 10% CO, stored at 5C 59 Ig—PP +OPP wan-LLDPE] 18.0 17.5 17.0 g 16.5 [a] 16.0 15.5 15.0 0 2 4 6 8 10 Date (days) 18.0 , 17.5 (D 16.5 1— \. [b] 16.0 15.5 15.0 4 1 . 7 4 0 2 4 6 8 10 Date (days) [C] 0 2 4 6 8 10 Date (days) Figure 26 Effect of MAP on theTSS, of mango slices packed in, [a] air, [b] 5% O, and 10% 00,, [c] 5% O, and 10% CO, stored at1OC 60 [+ PP +OPP +LLDPEI 10 2 4 E w 1: 2 0 T 7 l I 0 2 4 6 8 10 Time (days) 10 [b] Firmness (N) O N b 0) on O N .h 0) oo 1 0 Time (days) [C] Firrnness (N) O N b. O) 0) Time (days) Figure 27 Effect of MAP on the firmness, of mango slices packed in, [a] air, [b] 5% Oz and 10% C02, [c] 5% 02 and 10% CO, stored at 10C 61 packed in air had lower firmness than other treated mangoes. The firmness associated with mango slices is related to the atmospheric conditions within the package. According to Spencer (1965), elevated C02 and reduced 02 helps delay the loss of flesh firmness. Conversion of the insoluble pectin (protopectin) to soluble pectin during storage causes the reduction in firmness (Knee and Bartley, 1981). PPO. PPO activity increased during storage for all packaged mangoes (Figure 28 and 29). Mango slices packaged in OPP containing 10% CO2 and 5% 02 had lower PPO activity than the other MA packagings. This is in agreement with Siripanich and Kader (1985), who found that high CO2 concentrations reduced PPO activity. Low 02 concentration delays enzymatic browning because PPO has a relatively low affinity for oxygen (Burton, 1974). Therefore, packages with low 02 concentration and with greater 02 barrier have the potential to prevent browning. However, the 02 concentration must be high enough to maintain aerobic respiration. Moderate vacuum packaging in 80 pm polyethylene inhibited enzymatic browning over 10 days storage at 5°C (Heimdai, 1995). Microbial safety Mold and yeast were counted at the end of the storage period. Ready-to- ‘eat fruits and vegetables should have populations of; 1) yeast 104< CF U/g, mold 62 < 500 CFUIg, E.coli < 10 CFU/g and none of Salmonellae (Department of Medical Science, Thailand). Mango slices packed in OPP bags in 5% O2 and 10% CO2, and stored at 5°C had an acceptable quality after 13 days. No visible sign of decay was observed on the samples. No mold was found and the yeast population was 2x102 CFUIg. Therefore, treated mango slices were below the regulation set by the medical board. 63 HPP +OPP +LLDPE] 7:6 E. 4 . 23- . I ——————"-—-—* :5 2 ‘/ X1 0 3'- 0 f T 1 I 1 If 0 2 4 6 8 1o 12 14 Time(days) :46 ,3 5 2 1 O 1 i r r . . 0 2 4 6 8 10 12 14 Time(days) 1‘ .r‘ 6 f?- 5 E 4 3, 3 $3 2 5 1 & o . . - . - . 0 2 4 6 8 10 12 14 Time(days) [a] [b] [C] Figure 28 Effect of MAP on the PPO activity of mango slices packed in, [a] air, [b] 5% 02 and 10% 002, [c] 5% O2 and 10% C02 and stored at 5C I-o—PP +OPP -e—LLDPE Te 6 IE 5 . 4 JD“ 3 'o 2 [a] g 1 CL 0 fl 1 O. o 2 4 6 8 10 Time (days) ‘5" 6 .3 5 E 4 lg i D "8 3 [b1 ,_ 2 i X i o 1 - -~ ' O. n. o r . 4 . o 2 4 6 8 10 Time (days) «1‘ 6 ~—-—'—- ‘3 5 / '"E', 4 3 ‘____,___:r———’. «'2 3 - y [C] 53 2 6‘ 1 M _.. 4 o. a 0 j T 7 1 '~“ 0 2 4 6 8 10 Time (days) Figure 29 Effect of MAP on the PPO activity of mango slices packed in, [a] air, [b] 5% O2 and 10% 002, [c] 5% O2 and 10% CO2 and stored at 100 65 CHAPTER 4 CONCLUSION AND FUTURE RESEARCH 66 Conclusion Minimally processed mangoes are subject to discoloration reactions, associated with condition of the raw material, peeling, and slicing. Ascorbic acid (0.5%) was the most effective browning inhibitor for mango slices (Nam Dokmai). Washing with chlorine plus dipping in calcium chloride gave no better results than washing with chlorine only, with regards to the firmness. Temperature plays an important role in controlling quality. Acceptable visual quality was obtained with mango slices at 5°C, but flesh firmness dropped significantly after 3—day storage. 5°C may be too low to maintain flesh firmness. A suitable temperature should be higher than 5°C but lower than 10°C. The most effectives packaging conditions were obtained with an OPP package in combination with 5% 02 and 10% CO2. Carbon dioxide (10%) retarded enzymatic browning of the mango slices. Acceptable visual quality was retained for 13 days. Yeast and mold counts were lower than the regulations allowed by Department of Medical Science, Thailand. High CO2 and low 02 concentrations also reduced PPO activity and delayed the increase in T88. Further research is necessary to evaluate other factors (sensory evaluation, etc.) before the best conditions for storage of this minimally processed product can be recommended. Extended storage life was obtained through the combination of the following: ascorbic acid (0.5%) dip to reduce enzymatic browning, storage at 5°C, pack in OPP to minimize weight loss and to maintain high level of CO2, and flush with 5% 02 and 10% CO2 to reduce PPO. 67 FUTURE RESEARCH This research emphasized application of antibrowning agents and MAP to inhibit enzymatic browning in mango slices, “Nam Dokmai’ variety. However, there is still a vast body of knowledge that remains unexplored. Use of MAP requires further understanding of many interactive components. Below are just a few areas that could be of benefit for further researches: 0 Effect of maturities of mango fruits 0 Effect of low temperature on chilling injury 0 Effect of carbon dioxide on CO2 injury 0 Sensory evaluation of mango slices under MAP 68 APPENDIX A 69 Table 10: treatments on ‘L’ values. Dependent Variable: L value Analysis of Variance Procedure: the effect of antibrowning T e I Sum Mean . Source oyfquuares df Square F S'g' TREAT 214.050 3 71.350 23.120 0.000 TEMP 65.104 1 65.104 21.096 0.000 DATE 1027.357 5 205.471 66.581 0.000 Fl'REAT * TEMP 29.115 3 9.705 3.145 0.029 TREAT * DATE 68.044 15 4.536 1.470 0.134 TEMP * DATE 49.840 4 12.460 4.038 0.005 TREAT * TEMP * DATE 11.179 12 0.932 0.302 0.988 Table 11: treatments on ‘a’ values. Dependent Variable: 'a' value Analysis of Variance Procedure: the effect of antibrowning Source 1?;3332 df Mean Squarei F Sig. DATE 11.597 5 2.319 4.137 0.002 EAT 9.043 3 3.014 5.377 0.002 TEMP 0.037 1 0.037 0.066 0.799 DATE * TREAT 9.554 15 0.637 1.136 0.337 DATE * TEMP 9.678 4 2.420 4.316 0.003 TREAT * TEMP 2.291 3 0.764 1.362 0.260 DATE * TREAT * TEMP 3.433 12 0.286 0.510 0.903 70 Table 12: treatments on ‘b' values. Dependent Variable: 'b' value Analysis of Variance Procedure: the effect of antibrowning T e I Sum Mean . Source oI’quuares df Square F 519. DATE 170.154 5 34.031 10.400 0.000 TREAT 64.113 3 21.371 6.531 0.000 TEMP 27.879 1 27.879 8.520 0.004 DATE * TREAT 44.464 15 2.964 0.906 0.560 DATE * TEMP 7.111 4 1.778 0.543 0.704 TREAT * TEMP 3.325 3 1.108 0.339 0.797 DATE * TREAT * TEMP 10.041 12 0.837 0.256 0.994 Table 13: Analysis of Variance Procedure: the effect of CaCl2 treatments on flesh firmness. Dependent Variable: Firmness Type I Source Sum of df 523:; F Sig. Squares DATE 350.878 4 87.720 305.920 0.000 TEMP 0.515 1 0.515 2.152 0.148 CaCl2 1.251 2 0.530 2.205 0.119 DATE * TEMP 0.658 4 0.155 0.575 0.581 DATE * CaCl2 1.953 8 0.244 0.854 0.550 TEMP * CACL2 0.292 2 0.145 0.510 0.503 DATE * TEMP * CaCl2 0.348 8 0.043 0.152 0.995 71 Table 14: Analysis of Variance Procedure: the effect of each treatment and between treatments under modified atmospheric conditions to ‘L’ values. Dependent Variable: ‘L’ value Type I Sum Source of Squares df Square F 5'9' DATE 2375.35 6 395.892 801.290 0.000 TEMP 152.80 1 152.796 309.260 0.000 FILM 277.73 2 138.866 281.065 0.000 GAS 122.42 2 61.209 123.887 0.000 DATE * TEMP 55.77 4 13.941 28.217 0.000 DATE * FILM 85.49 12 7.124 14.419 0.000 TEMP * FILM 1.13 2 0.565 1.143 0.323 DATE * GAS 106.80 12 8.900 18.014 0.000 TEMP * GAS 24.62 2 12.310 24.915 0.000 FILM * GAS 10.66 4 2.664 5.393 0.001 DATE * TEMP * GAS 17.75 8 2.219 4.492 0.000 DATE * TEMP * FILM 6.25 8 0.781 1.581 0.139 DATE * FILM * GAS 14.61 24 0.609 1.232 0.232 TEMP * FILM * GAS 2.09 4 0.524 1.060 0.380 DATE * TEMP * FILM * GAS 10.99 16 0.687 1.390 0.160 72 Table 15: Analysis of Variance Procedure; the effect of each treatment and between treatments under modified atmospheric conditions to ‘a’ values. Dependent Variable: 'a' value Type I Source Sum of df 523:; F Sig. Squares DATE 86.052 6 14.342 9.963 0.000 TEMP 34.139 1 34.139 23.714 0.000 FILM 32.835 2 16.417 11.404 0.000 GAS 29.417 2 14.708 10.217 0.000 DATE * TEMP 27.652 4 6.913 4.802 0.001 DATE * FILM 21.467 12 1.789 1.243 0.264 TEMP * FILM 5.050 2 2.525 1.754 0.178 DATE * TEMP * FILM 8.514 8 1.064 0.739 0.657 DATE * GAS 20.873 12 1.739 1.208 0.287 TEMP * GAS 16.222 2 8.111 5.634 0.005 DATE * TEMP * GAS 11.220 8 1.403 0.974 0.460 FILM * GAS 1.176 4 0.294 0.204 0.936 DATE * FILM * GAS 15.529 24 0.647 0.449 0.987 TEMP * FILM * GAS 8.934 4 2.234 1.552 0.193 DATE * TEMP * FILM * GAS 8.334 16 0.521 0.362 0.988 73 Table 16: between treatments under modified atmospheric conditions to ‘b’ values. Dependent Variable: ‘b’ value Analysis of Variance Procedure; the effect of each treatment and Type I Source Sum of df $213235 F Sig. Squares DATE 511.027 6 85.171 40.287 0.000 TEMP 27.605 1 27.605 13.057 0.000 FILM 1.563 2 0.782 0.370 0.692 GAS 2.426 2 1.213 0.574 0.565 DATE * TEMP 14.237 4 3.559 1.684 0.159 DATE * FILM 34.460 12 2.872 1.358 0.197 TEMP * FILM 6.218 2 3.109 1.471 0.234 DATE * TEMP * FILM 24.573 8 3.072 1.453 0.183 DATE * GAS 38.803 12 3.234 1.530 0.125 TEMP * GAS 11.043 2 5.521 2.612 0.078 DATE * TEMP * GAS 25.774 8 3.222 1.524 0.157 FILM * GAS 14.018 4 3.505 1.658 0.165 DATE * FILM * GAS 95.885 24 3.995 1.890 0.015 TEMP * FILM * GAS 17.030 4 4.258 2.014 0.098 DATE * TEMP * FILM * GAS 26.903 16 1.681 0.795 0.688 74 Table 17: Analysis of Variance Procedure: the effect of each treatment and between treatments under modified atmospheric conditions to pH. Dependent Variable: pH Type i I Sum Source of or 523:; F Sig. Squar es ‘ DATE 1.894 3 0.531 5.496 0.002 TEMP 1.141 1 1.141 9.933 0.002 FILM 0.504 2 0.252 2.195 0.120 'MAP 0.330 2 0.155 1.438 0.245 DATE * TEMP 1.009 2 0.505 4.393 0.016 DATE * FILM 0.243 6 0.041 0.353 0.906 TEMP * FILM 0.405 2 0.203 1.766 0.179 DATE * TEMP * FILM 0.359 4 0.090 0.782 0.541 DATE * MAP 0.446 5 0.074 0.648 0.692 TEMP * MAP 0.260 2 0.130 1.130 0.329 DATE * TEMP * MAP 0.283 4 0.071 0.616 0.652 FILM * MAP 0.862 4 0.215 1.876 0.126 DATE * FILM * MAP 0.620 12 0.052 0.450 0.936 TEMP * FILM * MAP 0.335 4 0.084 0.729 0.576 DATE * TEMP * FILM * MAP 0.454 8 0.057 0.494 0.856 75 Table 18: Analysis of Variance Procedure: the effect of each treatment and between treatments under modified atmospheric conditions to %weight loss. Dependent Variable: %weight loss Type I Source Sum of df 5:32; F Sig. Squares DATE 9.340 3 3.113 228.944 0.000 TEMP 0.081 1 0.081 5.966 0.017 FILM 0.030 2 0.015 1.103 0.338 'MAP 0.016 2 0.008 0.589 0.558 DATE * TEMP 0.109 2 0.055 4.008 0.023 DATE * FILM 0.108 6 0.018 1.326 0.259 TEMP * FILM 0.019 2 0.010 0.715 0.493 DATE * TEMP * FILM 0.016 4 0.004 0.298 0.878 DATE * MAP 0.089 6 0.015 1.087 0.380 TEMP * MAP 0.132 2 0.066 4.839 0.011 DATE * TEMP * MAP 0.072 4 0.018 1.321 0.272 FILM * MAP 0.009 4 0.002 0.164 0.956 DATE * FILM * MAP 0.123 12 0.010 0.752 0.695 TEMP * FILM * MAP 0.061 4 0.015 1.115 0.357 DATE * TEMP * FILM * MAP 0.083 8 0.010 0.759 0.639 76 Table 19: between treatments under modified atmospheric conditions to TSS. Dependent Variable: TSS Analysis of Variance Procedure: the effect of each treatment and Type I Source Sum of df 5'23; F Sig. Squares DATE 25.919 3 8.640 9.661 0.000 TEMP 1.311 1 1.311 1.466 0.230 FILM 6.760 2 3.380 3.780 0.028 'MAP 1.448 2 0.724 0.809 0.450 DATE * TEMP 2.967 2 1.483 1.659 0.199 DATE * FILM 3.476 6 0.579 0.648 0.692 MP * FILM 0.046 2 0.023 0.026 0.975 DATE * TEMP * FILM 1.044 4 0.261 0.292 0.882 DATE * MAP 2.558 6 0.426 0.477 0.823 FI'EMP * MAP 1.017 2 0.508 0.569 0.569 DATE * TEMP * MAP 1.756 4 0.439 0.491 0.742 FILM * MAP 0.305 4 0.076 0.085 0.987 DATE * FILM * MAP 1.736 12 0.145 0.162 0.999 TEMP * FILM * MAP 0.220 4 0.055 0.062 0.993 DATE * TEMP * FILM * MAP 0.377 8 0.047 0.053 1.000 77 Table 20: between treatments under modified atmospheric conditions to flesh firmness. Dependent Variable: Flesh firmness Analysis of Variance Procedure: the effect of each treatment and Type I Source Sum of df 523:; F Sig. Squares DATE 726.059 5 145.212 128.233 0.000 . TEMP 4.606 1 4.606 4.067 0.047 FILM 1.455 2 0.727 0.642 0.528 GAS 12.034 2 6.017 5.314 0.007 DATE * TEMP 2.494 3 0.831 0.734 0.534 DATE * FILM 5.634 10 0.553 0.498 0.887 TEMP * FILM 12.206 2 6.103 5.389 0.006 DATE * TEMP * FILM 10.334 6 1.722 1.521 0.180 DATE * GAS 9.848 10 0.985 0.870 0.564 TEMP * GAS 5.193 2 2.596 2.293 0.107 DATE * TEMP * GAS 8.558 6 1.426 1.260 0.284 mm GAS 6.102 4 1.526 1.347 0.259 DATE * FILM * GAS 18.365 20 0.918 0.811 0.694 EMP: FILM * GAS 2.561 4 0.640 0.565 0.588 DATE * TEMP * FILM * GAS 12.063 12 1.005 0.888 0.552 78 Table 21: Dependent Variable: PPO Analysis of Variance Procedure: the effect of each treatment and between treatments under modified atmospheric conditions to PPO. Type I Source Sum of df 52:2; F Sig. Squares DATE 0.000 6 0.000 78.691 0.000 TEMP 0.000 1 0.000 126.489 0.000 FILM 0.000 2 0.000 34.633 0.000 GAS 0.000 2 0.000 3.362 0.038 DATE * TEMP 0.000 4 0.000 14.052 0.000 DATE * FILM 0.000 12 0.000 4.675 0.000 TEMP * FILM 0.000 2 0.000 0.389 0.679 DATE * TEMP * FILM 0.000 8 0.000 0.683 0.706 DATE * GAS 0.000 12 0.000 0.670 0.776 TEMP * GAS 0.000 2 0.000 1.267 0.286 DATE * TEMP * GAS 0.000 8 0.000 0.713 0.680 FILM * GAS 0.000 4 0.000 1.418 0.233 DATE * FILM * GAS 0.000 24 0.000 0.319 0.999 TEMP * FILM * GAS 0.000 4 0.000 0.723 0.578 DATE * TEMP * FILM * GAS 0.000 16 0.000 0.234 0.999 79 APPENDD( B 80 Table 22 Effect of antibrowninLagents on 'L' values of mango slices stored at 5 and 10°C. Lvalue 5°C 10°C Day Citric Ascorbic Plus Ctri Citric Ascorbic Plus Ctri 69.37 69.37 69.37 69.37 69.37 69.37 69.37 69.37 0 71.11 71.11 71.11 71.11 71.11 71.11 71.11 71.11 68.99 68.99 68.99 68.99 68.99 68.99 68.99 68.99 ave 69.82 69.82 69.82 69.82 69.82 69.82 69.82 69.82 67.45 68.52 67.33 64.29 64.44 67.59 64.94 64.55 1 69.16 70.10 67.24 67.51 69.68 69.18 63.25 63.66 65.90 68.33 67.39 69.40 65.90 68.15 64.54 65.64 ave 67.50 68.98 67.32 67.07 66.67 68.31 64.24 64.62 65.75 68.49 65.61 66.24 65.98 66.95 61.31 62.13 2 66.68 68.66 66.65 66.62 64.36 66.15 60.97 62.55 63.91 68.11 67.54 65.13 65.91 66.34 65.10 61.69 ave 67.07 68.74 66.60 66.00 65.42 66.48 62.46 62.12 66.70 67.99 66.70 64.94 59.88 67.20 55.70 59.80 4 64.97 68.52 64.36 63.46 64.17 63.32 59.40 60.33 66.23 67.99 64.33 65.19 65.92 65.51 65.64 60.89 ave 65.97 68.17 65.13 64.53 63.32 65.34 60.25 60.34 64.01 66.85 65.16 63.71 61.23 63.67 55.94 54.37 7 63.87 67.99 63.98 61.58 60.28 62.64 57.17 59.98 62.25 65.32 60.35 62.89 62.20 64.53 62.49 59.65 ave 63.38 66.72 63.16 62.73 61.24 63.61 58.53 58.00 61.86 65.07 59.48 62.19 10 62.17 65.26 60.98 59.19 60.49 64.78 62.55 58.87 ave 61.51 65.03 61.01 60.08 81 Table 23 Effect of Antibrowning agents on 'a' values of mango slices stored at 5 and 10°C. avalue 5°C 10°C Day Citiric Ascorbic Plus Ctrl Citric Ascorbic Plus Ctrl 6.42 6.42 6.42 6.42 6.42 6.42 6.42 6.42 0 5.64 5.64 5.64 5.64 5.64 5.64 5.64 5.64 6.00 6.00 6.00 6.00 6.00 6.00 6.00 6.00 ave 6.02 6.02 6.02 6.02 6.02 6.02 6.02 6.02 7.86 7.42 9.27 6.91 7.68 6.64 7.28 4.97 1 6.00 6.59 6.01 7.57 6.13 6.47 6.07 6.05 5.37 7.42 7.93 5.88 6.02 5.71 7.65 5.07 ave 6.41 7.14 7.74 6.79 6.61 6.27 7.00 5.36 5.32 6.31 7.47 7.64 5.99 6.02 6.11 6.28 2 7.60 5.50 6.71 6.73 6.16 5.63 8.14 5.15 6.23 6.52 6.42 5.67 7.74 6.06 7.16 4.99 ave 6.38 6.11 6.87 6.68 6.63 5.90 7.14 5.47 6.09 6.36 6.73 7.19 6.44 6.70 7.00 6.01 4 5.90 4.60 6.39 6.44 7.29 5.54 6.92 7.07 7.64 6.23 6.42 6.97 5.66 6.61 6.67 5.96 ave 6.54 5.73 6.51 6.87 6.46 6.28 6.86 6.35 7.13 6.72 6.24 5.70 7.00 7.91 7.55 7.66 7 5.41 7.03 6.96 6.67 6.73 7.97 8.41 7.33 5.46 4.65 8.02 7.11 6.73 7.10 7.74 7.34 ave 6.00 6.13 7.07 6.49 6.82 7.66 7.90 7.44 5.78 6.27 7.53 6.90 10 6.27 6.42 7.12 7.38 5.17 4.26 6.45 5.95 ave 5.74 5.65 7.03 6.74 82 Table 24 Effect of Antibrowning_a_gents on 'b' value of mango slices stored at 5 and 10°C. b value 5°C 10°C Day Citric Ascorbic Plus Ctri Citric Ascorbic Pius Ctri 26.47 26.47 26.47 26.47 26.47 26.47 26.47 26.47 0 25.52 25.52 25.52 25.52 25.52 25.52 25.52 25.52 26.60 26.60 26.60 26.60 26.60 26.80 26.60 26.60 ave 26.20 26.20 26.20 26.20 26.20 26.20 26.20 26.20 24.31 29.25 26.26 26.52 25.58 23.90 20.31 25.24 1 25.29 25.66 25.26 26.23 24.22 25.08 24.84 24.41 25.70 22.77 25.21 25.37 25.41 20.75 23.70 25.30 ave 25.10 25.89 25.58 26.04 25.07 23.24 22.95 24.98 28.09 25.67 20.24 26.72 23.49 24.64 22.90 24.99 2 24.67 25.10 27.05 25.74 26.76 22.89 22.45 25.29 22.87 23.94 24.64 25.77 23.97 22.33 22.80 24.48 ave 25.21 24.90 23.98 26.08 24.74 23.29 22.72 24.92 24.49 27.07 21.11 25.34 25.09 19.71 23.52 24.84 4 23.35 24.96 26.12 24.98 22.49 22.67 20.46 23.49 26.43 21.21 17.86 25.15 22.46 24.29 19.84 24.02 ave 24.76 24.41 21.70 25.16 23.35 22.22 21.27 24.12 25.36 25.97 26.02 23.88 22.42 24.35 20.45 22.93 7 21.09 24.50 22.13 23.81 22.73 24.01 23.44 22.69 23.64 23.27 21.03 25.65 22.56 22.75 21.33 23.10 ave 23.36 24.58 23.06 24.45 22.57 23.70 21.74 22.91 23.80 25.56 15.62 26.24 10 22.96 20.63 21.27 25.30 20.22 22.62 24.86 25.16 ave 22.33 22.94 20.58 25.57 83 Table 25 Effect of calcium dtlorIde on fish firmness of mango slices stored at S and at 10°C. Firmness (N) Day 5°C 10°C cm CaCl2 0.5% CaCl2 1.0% cm CaCl2 0.5% CaCl2 1.0% 7.235 7.235 7.235 7.235 7.235 7.235 0 8.257 8.257 8.257 8.257 8.257 8.257 7.766 7.766 7.766 7.766 7.766 7.766 ave 7.753 7.753 7.753 7.753 7.753 7.753 3.210 3.321 3.310 3.246 3.056 3.259 2 3.135 3.246 4.415 3.205 3.082 3.043 3.300 3.271 3.252 3.165 3.362 3.333 ave 3.215 3.279 3.659 3.205 3.167 3.212 3.574 3.384 3.550 3.219 3.206 3.286 3 2.223 2.722 3.593 2.490 3.564 3.318 2.332 3.392 3.470 2.211 2.962 3.578 ave 2.710 3.166 3.538 2.640 3.244 3.394 2.214 3.863 2.563 2.967 1.630 1.301 6 3.056 2.871 3.566 2.449 3.393 3.171 2.546 2.888 2.671 1.669 2.203 2.574 ave 2.605 3.207 2.933 2.362 2.409 2.349 2.900 2.340 3.119 2.854 1.628 1.641 8 1.905 2.427 3.119 2.488 2.851 2.854 1.960 2.450 2.112 2.207 1.724 3.104 ave 2.255 2.406 2.783 2.516 2.068 2.533 Table 26 Effect of polymericfilm type on 'L' value under modified atmosphere packaging. Mango slices were packed in PP, OPP and LLDPE films and stored at 5°C. L value Day PP OPP LLDPE Air 5002 10002 Air 5002 10002 Air 5002 10002 0 69.37 69.37 69.37 69.37 69.37 69.37 69.37 69.37 69.37 68.99 68.99 68.99 68.99 68.99 68.99 68.99 68.99 68.99 ave 69.18 69.18 69.18 69.18 69.18 69.18 69.18 69.18 69.18 1 68.85 67.88 67.83 68.80 67.48 68.54 68.57 66.35 67.41 68.56 66.88 68.16 69.36 67.99 68.04 67.60 66.38 67.76 ave 68.71 67.38 68.00 69.08 67.74 68.29 68.09 66.37 67.59 3 65.37 66.88 66.11 67.72 68.10 67.39 65.30 64.43 65.96 65.75 65.83 67.95 66.77 66.55 67.38 64.01 65.78 64.87 ave 65.56 66.36 67.03 67.25 67.33 67.39 64.66 65.1 1 65.42 6 63.05 64.37 65.22 64.89 65.76 64.29 60.66 62.45 62.42 62.91 64.70 64.83 64.76 64.39 65.93 61.99 61.58 60.89 ave 62.98 64.54 65.03 64.83 65.08 65.11 61.33 62.02 61.66 8 60.59 63.39 63.88 63.76 64.41 64.04 58.87 59.77 61.66 61 .24 63.87 64.76 63.36 63.81 64.33 59.95 57.35 60.01 ave 60.92 63.63 64.32 63.56 64.11 64.19 59.41 58.56 60.84 10 59.81 63.83 63.23 61.77 63.33 64.57 57.11 58.69 60.01 59.44 61.49 63.63 60.89 63.41 63.15 £11.47 57.21 58.67 ave 59.63 62.66 63.43 61.33 63.37 63.86 57.29 57.95 59.34 13 56.97 61.25 63.32 58.34 61.95 63.55 55.59 58.88 58.77 57.19 62.50 62.86 58.77 62.81 63.69 56.73 56.60 59.34 ave 57.08 61.88 63.09 58.56 62.38 63.62 56.16 57.74 59.06 Table 27 Effect of polymeric film type on 'L' value under modified atmosphere packaging. Mango slices were packed in PP, OPP and LLDPE films and stored at 10°C. L value Day PP OPP LLDPE _ Air 5002 10002 Air 5002 10002 Air 5002 10002 0 69.37 69.37 69.37 69.37 69.37 69.37 69.37 69.37 69.37 68.99 68.99 68.99 68.99 68.99 68.99 68.99 68.99 68.99 ave 69.18 69.18 69.18 69.18 69.18 69.18 69.18 69.18 69.18 1 67.17 68.21 66.47 67.41 67.28 67.98 66.67 64.86 66.00 66.82 66.66 67.85 67.03 68.50 67.26 65.30 62.97 65.7L ave 67.00 67.44 67.16 67.22 67.89 67.62 65.99 63.92 65.87 3 63.44 64.78 65.47 65.37 65.92 65.66 61.84 61.55 63.98 63.52 64.99 64.89 64.89 65.41 65.76 59.13 60.96 64.50 ave 63.48 64.89 65.18 65.13 65.67 65.71 60.49 61.26 64.24 6 59.47 60.11 64.07 60.61 62.72 64.03 57.62 59.42 62.74 58.84 61.32 63.89 59.77 63.52 64.73 56.75 58.16 60.72 ave 59.16 60.72 63.98 60.19 63.12 64.38 57.19 58.79 61.73 8 57.30 60.74 63.24 57.42 61.00 63.33 54.14 58.71 59.02 56.14 59.18 61.29 58.12 60.65 62.80 53.87 56.49 58.89 ave 56.72 59.96 62.27 57.77 60.83 63.07 54.01 57.60 58.96 85 Table 28 Effect of polymeric film type on 'a' value under modified atmosphere packaging. Mango slices were packed in PP, OPP and LLDPE films and stored at 5°C. 8 value Day PP OPP LLDPE Air 500, 1000, Air 500, 1000, Air 500, 1000, 0 4.88 4.88 4.88 4.88 4.88 4.88 4.88 4.88 4.88 4.19 4.19 4.19 4.19 4.19 4.19 4.19 4.19 4.19 ave 4.54 4.54 4.54 4.54 4.54 4.54 4.54 4.54 4.54 1 2.31 2.15 3.20 2.10 4.39 2.95 2.13 3.76 1.89 3.24 2.01 0.55 2.30 2.35 2.54 2.75 3.33 1.68 ave 2.78 2.08 1.88 2.20 3.37 2.75 2.44 3.55 1.79 3 4.98 3.86 2.98 3.40 2.65 1.30 0.17 3.22 0.92 4.25 2.00 2.73 1.83 1.30 3.26 3.75 1.72 2.33 ave 4.62 2.93 2.86 2.62 1.98 2.28 1.96 2.47 1.63 6 4.91 2.85 4.06 1.19 1.65 2.02 3.56 2.86 3.64 3.34 4.36 3.27 4.08 3.65 3.37 2.53 5.37 2.08 ave 4.13 3.61 3.67 2.64 2.65 2.70 3.05 4.12 2.86 8 5.10 3.30 4.16 2.28 3.72 4.47 1.99 3.12 3.23 4.95 3.52 3.57 2.07 -1.35 -0.84 1.84 1.99 1.67 ave 5.03 3.41 3.87 2.18 1.19 1.82 1.92 2.56 2.45 10 4.50 5.51 4.60 3.97 1.88 3.16 0.61 3.06 2.68 5.73 4.65 1.76 0.49 4.03 0.67 3.71 5.45 2.63 ave 5.12 5.08 3.18 2.23 2.96 1.92 2.16 4.26 2.66 13 3.35 1.88 3.02 3.54 4.76 3.55 2.99 1.23 3.31 5.19 5.25 4.11 5.28 0.28 2.73 4.33 3.34 2.03 ave 4.27 3.57 3.57 4.41 2.52 3.14 3.66 2.29 2.67 Table 29 Effect of polymeric film type on 'a' value under modified atmosphere packaging. Mangg slices were packed in PP, OPP and LLDPE films and stored at 10’C. a value Day PP OPP LLDPE Air 500, 1000, Air 500, 1000, Air 500, 1000, 0 4.88 4.88 4.88 4.88 4.88 4.88 4.88 4.88 4.88 4.19 4.19 4.19 4.19 4.19 4.19 4.19 4.19 4.19 ave 4.54 4.54 4.54 4.54 4.54 4.54 4.54 4.54 4.54 1 2.67 3.34 4.23 4.59 2.12 2.04 4.15 2.54 1.92 2.82 2.12 4.16 2.73 2.29 1.05 4.19 3.20 1.87 ave 2.75 2.73 4.20 3.66 2.21 1.55 4.1%; 2.87 1.90 3 6.15 3.18 3.23 2.10 1.78 0.32 4.28 2.26 2.17 3.56 6.27 2.69 2.69 2.86 2.06 5.27 5.57 2.06 ave 4.86 4.73 2.96 2.40 2.32 1.19 4.78 3.92 2.12 6 5.42 5.73 3.31 2.99 6.43 3.33 5.71 3.99 2.48 7.45 3.72 2.68 7.30 1.95 3.43 7.31 3.11 5.11 ave 6.44 4.73 3.00 5.15 4.19 3.38 6.51 3.55 3.80 8 5.77 5.75 3.00 7.31 3.89 3.33 7.71 4.93 4.76 7.89 6.36 5.41 4.56 3.01 2.28 6.84 4.36 5.36 ave 6.83 6.06 4.21 5.94 3.45 2.81 7.28 4.65 5.06 86 Table 30 Effect of polymeric film type on 'b' value under modified atmosphere packaging. Mango slices were packed in PP, OPP and LLDPE films and stored at 5°C. b value Day PP OPP LLDPE Air 5002 10002 Air 5002 10002 Air 5002 10002 0 30.80 30.80 30.80 30.80 30.80 30.80 30.80 30.80 30.80 31.58 31.58 31.58 31.58 31.58 31.58 31.58 31.58 31.58 ave 31.19 31.19 31.19 31.19 31.19 31.19 31.19 31.19 31.19 1 29.59 29.79 28.29 32.88 30.15 30.80 30.79 31 .58 28.74 29.14 29.77 30.44 30.82 30.22 30.85 25.96 29.21 31.25 ave 29.37 29.78 29.37 31.85 30.19 30.83 28.38 30.40 30.00 3 27.83 30.25 30.31 28.55 28.33 28.69 28.97 28.06 27.48 28.83 25.08 25.73 29.04 27.53 29.43 28.90 29.19 27.97 ave 28.33 27.67 28.02 28.80 27.93 29.06 28.94 28.63 27.73 6 30.46 25.09 29.06 25.65 27.69 25.88 29.25 30.86 29.37 29.84 27.25 28.76 27.93 31.87 26.96 30.26 27.29 30.36 ave 30.15 26.17 28.91 26.79 29.78 26.42 29.76 29.08 29.87 8 30.08 26.09 26.96 30.14 27.73 27.24 29.67 29.54 25.19 30.08 23.58 25.55 30.07 26.93 27.09 27.12 28.63 26.81 ave 30.08 24.84 26.26 30.11 27.33 27.17 28.40 29.09 26.00 10 26.63 25.76 24.58 23.41 28.19 26.05 25.00 26.58 29.64 25.05 27.39 28.66 24.21 26.24 28.20 28.29 21.95 26.14 ave 25.84 26.58 26.62 23.81 27.22 27.13 26.65 24.27 27.89 13 27.12 26.87 30.42 28.02 24.65 29.19 27.09 28.68 22.49 28.09 28.61 30.16 26.51 25.02 28.96 24.34 26.22 25.72 ave 27.61 27.74 30.29 27.27 24.84 29.08 25.72 27.45 24.1 1 Table 31 Effect of polymeric film type on 'b' value under modified atmosphere packaging. Mango slices were packed in PP, OPP and LLDPE films and stored at 10°C. b value Day PP OPP LLDPE Air 5002 10002 Air 5002 10002 Air 5002 10002 0 30.80 30.80 30.80 30.80 30.80 30.80 30.80 30.80 30.80 31.58 31.58 31.58 31.58 31.58 31.58 31.58 31.58 31.58 ave 31.19 31.19 31.19 31.19 31.19 31.19 31.19 31.19 31.19 1 30.39 29.36 30.27 29.88 30.26 27.35 28.62 28.35 27.25 30.57 304.21 28.60 28.62 27.28 29.92 29.40 30.40 28.00 ave 30.48 29.79 29.44 29.25 28.77 28.64 29.01 29.38 27.63 3 29.09 26.04 27.10 25.99 26.65 27.08 30.55 26.83 27.99 26.01 28.86 29.03 27.14 28.09 30.12 28.72 27.59 27.; ave 27.55 27.45 28.07 26.57 27.37 28.60 29.64 27.21 27.70 6 29.03 30.01 25.84 26.48 27.49 29.59 25.71 27.27 27.39 22.89 28.23 29.28 23.08 28.40 27.87 24.19 22.36 27.51 ave 25.96 29.12 27.56 24.78 27.95 28.73 24.95 24.82 27.45 8 26.90 24.55 26.61 26.68 26.52 29.25 27.93 26.75 27.27 27.77 25.97 27.24 24.18 28.26 27.73 28.25 27.97 24.84 ave 27.34 25.26 26.93 25.43 27.39 28.49 28.09 27.36 26.06 87 Table 32 Effect of modified atmosphere packaging on pH, of mango slices packed in PP, OPP and LLDPE films and stored at 5°C. pH Day PP OPP LLDPE Air 5002 10002 Air 5002 10002 Air 5002 10002 0 3.55 3.55 3.55 3.55 3.55 3.55 3.55 3.55 3.55 4.23 4.23 4.23 4.23 4.23 4.23 4.23 4.23 4.23 ave 3.89 3.89 3.89 3.89 3.89 3.89 3.89 3.89 3.89 3 4.15 3.61 3.04 3.20 3.22 3.49 3.38 3.84 3.54 3.90 3.50 4.01 3.57 3.17 3.24 3.26 3.45 3.64 ave 4.03 3.56 3.53 3.39 3.20 3.37 3.32 3.65 3.59 8 3.86 3.71 3.58 3.31 3.05 3.19 3.30 3.64 3.97 4.10 3.76 3.38 3.38 3.35 3.34 3.39 3.62 3.95 ave 3.98 3.74 3.48 3.35 3.20 3.27 3.35 3.63 3.96 13 3.82 4.02 3.28 4.05 3.46 3.74 3.72 3.59 4.11 3.72 3.61 3.45 3.20 3.41 3.44 3.73 4.17 3.65 ave 3.77 3.82 3.37 3.63 3.44 3.59 3.73 3.88 3.88 Table 33 Effect of modified atmosphere packaging on pH, of mango slices packed in PP, OPP and LLDPE films and stored at 10°C. pH Day PP OPP LLDPE Air 5002 10002 Air 5002 10002 Air 5002 10002 0 3.55 3.55 3.55 3.55 3.55 3.55 3.55 3.55 3.55 4.23 4.23 4.23 4.23 4.23 4.23 4.23 4.23 4.23 ave 3.89 3.89 3.89 3.89 3.89 3.89 3.89 3.89 3.89 3 3.64 3.80 3.78 3.45 3.63 3.44 3.34 3.61 3.96 3.72 3.88 3.55 3.36 4.11 3.39 4.04 3.98 3.90 ave 3.68 3.84 3.67 3.41 3.87 3.42 3.69 3.80 3.93 8 3.92 3.80 3.79 4.48 3.56 4.21 4.54 3.71 3.78 4.20 3.93 3.96 4.62 4.23 3.29 4.36 3.96 3.90 ave 4.06 3.87 3.88 4.55 3.90 3.75 4.45 3.84 3.84 88 Table 34 Effect of modified atmosphere packaging on weight loss of mango slices packed in PP, OPP and LLDPE films and stored at 5°C. %weight loss Day PP OPP LLDPE Alf 5002 1 0C02 Air 5002 1 0002 Air 5002 1 0C02 3 0.34 0.45 0.38 0.32 0.32 0.42 0.28 0.44 0.60 0.35 0.48 0.40 0.37 0.35 0.50 0.39 0.45 0.60 ave 0.35 0.47 0.39 0.35 0.34 0.46 0.34 0.45 0.60 8 0.56 0.53 0.62 0.54 0.42 0.98 0.52 0.45 0.65 0.52 0.55 0.65 0.45 0.45 0.10 0.55 0.43 0.70 ave 0.54 0.54 0.64 0.50 0.44 0.54 0.54 0.44 0.68 13 0.64 0.71 0.71 0.67 0.65 0.98 0.62 0.73 0.79 0.66 0.75 0.74 0.59 0.67 0.10 0.62 0.77 0.82 ave 0.65 0.73 0.73 0.63 0.66 0.54 0.62 0.75 0.81 Table 35 Effect of modified atmosphere packaging on weight loss, of mango slices packed in PP, OPP and LLDPE films and stored at 10°C. %weight loss Day PP ‘ OPP LLDPE Alf 5002 1 OCOz AII’ 5C02 10002 Air 5002 10002 3 0.39 0.23 0.36 0.45 0.41 0.43 0.59 0.50 0.43 0.44 0.31 0.36 0.41 0.37 0.39 0.61 0.54 0.44 ave 0.42 0.27 0.36 0.43 0.39 0.41 0.60 0.52 0.44 8 0.87 0.51 0.69 0.81 0.68 0.60 0.93 0.63 0.66 0.90 0.65 0.67 0.84 0.58 0.60 0.90 0.78 0.70 ave 0.89 0.58 0.68 0.83 0.63 0.60 0.92 0.71 0.68 89 Table 36 Effect of modified atmosphere packaging on the T85, of mango slices packed in PP, OPP and LLDPE films and stored at 5°C. TSS Day PP OPP LLDPE Air 5C02 1 OCOZ Air 5C02 1 0002 Air 5C0; 10002 0 15.4 15.4 15.4 15.4 15.4 15.4 15.4 15.4 15.4 15.6 15.6 15.6 15.6 15.6 15.6 15.6 15.6 15.6 ave 15.5 15.5 15.5 15.5 15.5 15.5 15.5 15.5 15.5 3 16.8 16.0 18.4 15.4 16.0 16.2 18.8 15.3 16.9 17.0 15.4 13.7 17.4 15.0 16.2 15.5 16.1 15.6 ave 16.9 15.7 16.1 16.4 15.5 16.2 17.2 15.7 16.3 8 17.8 19.1 17.4 15.2 15.4 16.0 18.8 16.4 16.8 15.0 14.4 16.2 16.2 16.2 16.8 15.0 17.0 18.0 ave 16.4 16.8 16.8 15.7 15.8 16.4 16.9 16.7 17.4 13 16.4 16.0 16.0 17.0 15.7 15.4 17.2 16.6 16.5 17.1 16.0 17.0 14.4 15.5 15.8 17.1 16.6 16.4 ave 16.8 16.0 16.5 15.7 15.6 15.6 17.2 16.6 16.5 Table 37 Effect of modified atmosphere packaging on the T88, of mango slices packed in PP, OPP and LLDPE films and stored at 10°C. TSS Day PP OPP LLDPE Air 5002 10002 Air 5002 10002 AIR 5002 10002 0 15.4 15.4 15.4 15.4 15.4 15.4 15.4 15.4 15.4 15.6 15.6 15.6 15.6 15.6 15.6 15.6 15.6 15.6 ave 15.5 15.5 15.5 15.5 15.5 15.5 15.5 15.5 15.5 3 17.5 17.0 17.0 16.0 16.7 16.0 17.7 16.7 17.5 17.4 16.8 16.5 16.7 16.8 16.2 17.3 17.8 16.5 ave 17.5 16.9 16.8 16.4 16.8 16.1 17.5 17.3 17.0 8 16.0 16.6 16.0 16.3 15.0 16.5 16.4 16.0 17.2 16.6 16.8 16.0 17.0 17.3 15.6 17.4 17.3 1'_I._2__ ave 16.3 16.7 16.0 16.7 16.2 16.1 16.9 16.7 17.2 90 Table 38 Effect of modified atmosphere packaging on the firmness, of mango slices packed in PP, OPP and LLDPE films and stored at 5°C. Firmness (N) Day PP OPP LLDPE Air 5C02 1 0002 AIT 5002 1 0002 Air 5002 10002 0 7.235 7.235 7.235 7.235 7.235 7.235 7.235 7.235 7.235 8.257 8.257 8.257 8.257 8.257 8.257 8.257 8.257 8.257 ave 7.746 7.746 7.746 7.746 7.746 7.746 7.746 7.746 7.746 3 3.052 3.815 5.341 3.815 5.341 3.052 5.341 9.155 3.815 4.578 3.052 6.866 3.052 5.341 4.578 3.052 3.815 4.518_ ave 3.815 3.434 6.104 3.434 5.341 3.815 4.197 6.485 4.197 6 4.578 3.815 2.289 3.052 5.341 2.289 4.578 6.104 5.341 3.052 4.578 4.578 5.341 3.851 3.052 2.289 5.341 5.341 ave 3.815 4.197 3.434 4.197 4.596 2.671 3.434 5.723 5.341 8 2.289 2.289 2.289 3.815 4.629 3.052 4.104 4.578 3.052 3.052 3.815 3.052 3.052 3.815 3.052 3.815 4.578 4.578 ave 2.671 3.052 2.671 3.434 4.222 3.052 3.960 4.578 3.815 10 3.052 3.052 5.341 3.052 4.886 4.578 4.392 3.052 3.052 3.052 3.052 3.815 3.815 3.815 5.341 2.289 4.578 5.341 ave 3.052 3.052 4.578 3.434 4.351 4.960 3.341 3.815 4.197 13 3.052 6.104 3.052 2.289 3.052 3.052 4.578 6.866 3.052 2.289 2.289 5.341 5.341 3.052 2.289 3.052 2.289 2.289 ave 2.671 4.197 4.197 3.815 3.052 2.671 3.815 4.578 2.671 Table 39 Effect of modified atmosphere packaging on the firmness, of mango slices packed in PP, OPP and LLDPE films and stored at 10°C. Firmness (N) Day PP OPP LLDPE Air 5C0; 1 0002 Air 5002 10002 NT 5002 10002 0 7.235 7.235 7.235 7.235 7.235 7.235 7.235 7.235 7.235 8.257 8.257 8.257 8.257 8.257 8.257 8.257 8.257 8.257 ave 7.746 7.746 7.746 7.746 7.746 7.746 7.746 7.746 7.746 3 3.052 4.578 3.815 5.341 5.341 6.104 2.289 2.289 3.052 3.052 3.815 3.052 4.578 5.341 3.052 3.052 3.815 3.815 ave 3.052 4.197 3.434 4.960 5.341 4.578 2.671 3.052 3.434 6 2.289 4.578 4.578 3.052 5.341 5.341 2.289 3.815 4.578 2.289 3.052 6.104 5.341 3.052 4.578 2.289 3.052 5.341 ave 2.289 3.815 5.341 4.197 4.197 4.960 2.289 3.434 4.960 8 3.052 3.052 3.052 1.526 3.052 3.052 2.289 3.052 3.052 4.578 2.289 3.815 2.289 3.052 4.578 1.526 3.052 3.052 ave 3.815 2.671 3.434 1.908 3.052 3.815 1.908 3.052 3.052 91 Table 40 Effect of modified atmosphere packaging on the PPO activity, of mango slices packed in PP, OPP and LLDPE films and stored at 5°C. PPO (U.ml".fl Day PP OPP LLDPE Air 5002 10002 Air 5002 10002 Air 5002 10002 0 0.0018 0.0018 0.0018 0.0018 0.0018 0.0018 0.0018 0.0018 0.0018 0.0023 0.0023 0.0023 0.0023 0.0023 0.0023 0.0023 0.0023 0.0023 ave 0.0021 0.0021 0.0021 0.0021 0.0021 0.0021 0.0021 0.0021 0.0021 1 0.0022 0.0029 0.0023 0.0018 0.0025 0.0024 0.0020 0.0021 0.0019 0.0019 0.0019 0.0022 0.0020 0.0019 0.0024 0.0022 0.0021 0.0025 ave 0.0021 0.0024 0.0023 0.0019 0.0022 0.0024 0.0021 0.0021 0.0022 3 0.0025 0.0026 0.0026 0.0014 0.0023 0.0022 0.0030 0.0029 0.0035 0.0029 0.0023 0.0023 0.0025 0.0020 0.0028 0.0033 0.0028 0.0021 ave 0.0027 0.0025 0.0025 0.0020 0.0022 0.0025 0.0032 0.0029 0.0028 6 0.0033 0.0025 0.0030 0.0028 0.0026 0.0022 0.0038 0.0027 0.0031 0.0025 0.0027 0.0022 0.0022 0.0022 0.0024 0.0035 0.0031 0.0031 ave 0.0029 0.0026 0.0026 0.0025 0.0024 0.0023 0.0037 0.0029 0.0031 8 0.0027 0.0044 0.0024 0.0022 0.0021 0.0027 0.0038 0.0030 0.0032 0.0034 0.0017 0.0034 0.0032 0.0022 0.0029 0.0040 0.0039 0.0034 ave 0.0031 0.0031 0.0029 0.0027 0.0022 0.0028 0.0039 0.0035 0.0033 10 0.0036 0.0033 0.0038 0.0029 0.0032 0.0028 0.0044 0.0037 0.0044 0.0036 0.0039 0.0034 0.0030 0.0029 0.0029 0.0044 0.0039 0.0034 ave 0.0036 0.0036 0.0036 0.0030 0.0031 0.0029 0.0044 0.0038 0.0039 13 0.0034 0.0035 0.0039 0.0032 0.0025 0.0033 0.0050 0.0040 0.0040 0.0040 0.0037 0.0030 0.0034 0.0031 0.0029 0.0049 0.0046 0.0043 ave 0.0037 0.0036 0.0035 0.0033 0.0028 0.0031 0.0050 0.0043 0.0042 Table 41 Effect of modified atmosphere packaging on the PPO activity, of mango slices packed in PP, OPP and LLDPE films and stored at 10°C. PPO (U.ml".d") Day PP OPP LLDPE Air 5C02 10002 NY 5C0; 10002 Air 5002 10CO2 0 0.0018 0.0018 0.0018 0.0018 0.0018 0.0018 0.0018 0.0018 0.0018 0.0023 0.0023 0.0023 0.0023 0.0023 0.0023 0.0023 0.0023 0.0023 ave 0.0021 0.0021 0.0021 0.0021 0.0021 0.0021 0.0021 0.0021 0.0021 1 0.0026 0.0023 0.0025 0.0030 0.0021 0.0026 0.0025 0.0028 0.0025 0.0029 0.0026 0.0028 0.0022 0.0031 0.0020 0.0026 0.0021 0.0024 ave 0.0028 0.0025 0.0027 0.0026 0.0026 0.0023 0.0026 0.0025 0.0025 3 0.0036 0.0033 0.0035 0.0032 0.0039 0.0028 0.0039 0.0036 0.0032 0.0029 0.0039 0.0033 0.0037 0.0029 0.0032 0.0035 0.0034 0.0034 ave 0.0033 0.0036 0.0034 0.0035 0.0034 0.0030 0.0037 0.0035 0.0033 6 0.0038 0.0040 0.0039 0.0038 0.0034 0.0034 0.0043 0.0036 0.0039 0.0034 0.0037 0.0035 0.0031 0.0041 0.0035 0.0038 0.0042 0.0037 ave 0.0036 0.0039 0.0037 0.0035 0.0038 0.0034 0.0041 0.0039 0.0038 8 0.0042 0.0041 0.0041 0.0043 0.0039 0.0031 0.0058 0.0048 0.0049 0.0040 0.0049 0.0033 0.0044 0.0034 0.0038 0.0054 0.0051 0.0047 ave 0.0041 0.0045 0.0037 0.0044 0.0037 0.0035 0.0058 0.0050 0.0048 92 i: slices in different films stored at 5°C concentration Table 42 Changes in CO, concentration of Day Air 5 002 10002 Air 5 002 10002 ' 5002 . 0.33 5.00 10.00 5.00 10.00 . 5.00 1 1 3.80 8.21 11.63 . 7.28 8.30 . 6.49 4 1 4.63 8.91 10.52 . 6.27 6.94 . 2.58 1 1 4 6.47 7.73 12.65 . 9.47 . 4.82 10. . 1 5.68 10.65 9.79 . 4.07 1 1 . 8.20 11.07 12.98 9.44 . 4.58 4.15 1 1 11 14 6.78 10.19 10.41 14.57 11.86 4.05 4.06 ave Table 43 Changes in CO2 concentration of slices packed In different films stored at 10'C concentration Day PP Air 5002 10002 ' 5002 10002 Air 500, 1 0.33 5.00 10.00 . 5.00 10.00 0.33 5.00 1 1 . 4 6.33 10.01 12.10 9.78 12.57 5.19 6.39 5.56 5.79 5.39 6.88 . 7.68 . 4.77 3.35 1 9.96 8.75 9.17 4.44 1 93 Table 44 Changes in 02 concentration of mango slices packed In different packaging films stored at 5°C 02 concentration Day PP OPP LLDPE Air 5CO2 1 0002 Air 5CO2 1 0C02 Air 5CO2 1 0CO2 0 21.00 5.00 5.00 21.00 5.00 5.00 21.00 5.00 5.00 21.00 5.00 5.00 21.00 5.00 5.00 21.00 5.00 5.00 ave 21.00 5.00 5.00 21.00 5.00 5.00 21.00 5.00 5.00 1 19.28 8.67 8.54 19.15 7.63 8.27 17.71 8.34 7.63 18.58 7.90 9.23 18.38 6.88 7.64 18.42 8.52 7.63 ave 18.93 8.29 8.89 18.77 7.26 7.96 18.07 8.43 7.63 3 16.08 8.22 9.84 16.89 7.26 7.62 17.29 9.52 9.36 15.44 8.95 8.29 18.46 7.72 6.55 15.17 7.13 9.47 ave 15.76 8.58 9.06 17.67 7.49 7.09 16.23 8.33 9.42 6 13.65 7.20 7.71 11.90 4.76 5.52 13.15 6.38 8.60 13.65 7.12 7.67 11.94 4.32 5.23 13.11 6.34 8.51 ave 13.65 7.16 7.69 11.92 4.54 5.37 13.13 6.36 8.56 8 12.02 5.83 6.14 9.70 4.02 4.82 11.37 5.36 7.80 12.40 6.96 5.93 9.30 3.93 4.95 10.62 5.24 7.00 ave 12.21 6.40 6.04 9.50 3.97 4.89 10.99 5.30 7.40 10 8.96 6.66 6.72 7.22 4.51 4.48 9.49 8.84 8.88 8.22 6.99 6.53 9.15 4.92 5.14 8.91 8.64 7.79 ave 8.59 6.83 6.62 8.19 4.71 4.81 9.20 8.74 8.34 13 9.00 6.79 8.02 6.97 5.98 5.31 8.80 8.11 8.67 9.30 7.24 7.52 6.98 5.76 5.69 8.98 8.64 8.51 ave 9.15 7.02 7.77 6.98 5.87 5.50 8.89 8.37 8.59 Table 45 Changes in 02 concentration of mango slices packed in different packaging films stored at 10°C 02 concentration Day PP OPP LLDPE Air 5002 10002 Air 5002 10002 Air 5002 10002 0 21.00 5.00 5.00 21.00 5.00 5.00 21.00 5.00 5.00 21.00 5.00 5.00 21.00 5.00 5.00 21.00 5.00 5.00 ave 21.00 5.00 5.00 21.00 5.00 5.00 21.00 5.00 5.00 1 16.75 7.45 8.27 15.97 7.24 6.97 17.90 8.22 6.54 16.69 8.10 8.22 17.94 7.45 6.78 16.96 9.51 6.71 ave 16.72 7.78 8.25 16.95 7.34 6.87 17.43 8.87 6.63 3 13.59 9.39 7.83 12.10 7.30 6.87 13.46 9.98 9.59 11.71 7.38 8.18 11.61 7.87 6.96 14.68 11.05 8.20 ave 12.65 8.39 8.00 11.86 7.58 6.91 14.07 10.52 8.89 6 7.36 8.11 4.37 9.29 6.44 6.14 9.19 7.91 6.81 7.81 7.53 7.13 9.87 4.64 5.26 12.82 9.17 6.57 ave 7.59 7.82 5.75 9.58 5.54 5.70 11.01 8.54 6.69 8 7.79 8.75 6.49 9.03 6.23 6.23 7.74 9.35 6.88 6.74 8.29 5.89 8.53 6.72 6.42 8.15 9.46 7.51 ave 7.27 8.52 6.19 8.78 6.48 6.33 7.95 9.41 7.19 94 BIBLIOGRAPHY AOA0.1995. 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