EVALUATION OF PHYSICO-CHEMICAL CHANGES IN MINIMALLY PROCESSED FRUITS AND VEGETABLES BY ACTIVE PACKAGING

EVALUATION OF PHYSICO-CHEMICAL CHANGES IN MINIMALLY PROCESSED FRUITS AND VEGETABLES BY ACTIVE PACKAGING 5 5.1 INTRODUCTION Peeling, cutting and shredding in minimal processed (MP) produce changes from a relatively stable product with a shelf-life of several weeks to a perishable one than whole produce. To extend the shelf-life of MP produce active packaging (AP) concept have been applied and this chapter deals with the study on physico-chemical and physiological analysis of minimally processed (MP) products of fruits and vegetables during storage at refrigerated conditions (5±1 C). Five treatments of AP (O 2 scavenger, CO 2 scavenger, ethylene scavenger, moisture scavenger and chitosan based antimicrobial coating) were selected for the study, and their effects were observed on apple slices, banana slices, orange fragments, tomato slices, cauliflower florets and shredded spinach, samples without treatments were taken as control. The treated fruits and vegetables were significantly different than control (P0.05) for physiological loss in weight (PLW), moisture content, total soluble solids (TSS), titratable acidity, ascorbic acid, total sugars, pectin, phenols, tannins, polyphenol oxidase activity, texture, firmness. Graphical representation of the results are incorporated here where as the data in tabular form are presented in Appendices (Annexure-1). 5.2 RESULTS AND DISCUSSION 5.2.1 Effect of active packaging concepts on the qualitative parameters of fruits and vegetables 5.2.1.1 Physiological loss in weight (PLW) Observations regarding the physiological loss in weight (PLW) of fresh-cut fruits and vegetables are presented in Fig 5.1(a) for apple, 5.1(b) for banana, 5.1(c) for orange, 5.1(d) for tomato, 5.1(e) for cauliflower and 5.1(f) for spinach and their results are summarized in Table 5.1 (MP fruits) and Tables 5.2 (MP vegetables). Results for physiological loss in weight (PLW) in MP apple are represented in Table 5.1 and the observations regarding PLW in MP apple are presented in Fig. 5.1(a). It was observed that at 15 th day of storage (final day) chitosan based coating was most effective in prevention of PLW 0.67% whereas control samples showed lesser PLW value 0.93% than 54

rest all the treatments. All the scavenging treatments had registered a negative impact on PLW parameter. Maximum loss was observed in case of moisture scavenger treatment 2.49% followed by samples treated with ethylene scavenger 2.47%. PLW was mainly attributed by moisture content of commodity. Fig. 5.1(a): Effect of active packaging on PLW (%) of MP apple Fig. 5.1(b) and Table 5.1 present the observations regarding PLW in MP banana. At 15 th day highest PLW value 2.03% was recorded in samples treated with moisture scavenger followed by ethylene scavenger treated samples 2.02%, O 2 scavenger treated samples 1.59%, samples treated with CO 2 scavenger 1.46%, control samples 0.77% and lowest value 0.56% was observed in fruit slices treated with chitosan coating. Fig. 5.1(b): Effect of active packaging on PLW (%) of MP banana Fig. 5.1(c) and Table 5.1 depict the observations regarding PLW in MP orange. For PLW in orange, pattern of losses were similar to that of apple and banana. Maximum PLW value 2.47% was recorded in orange samples treated with ethylene scavenger followed by moisture scavenger treated samples 2.34% and lowest PLW value 0.60% was observed in chitosan coated orange fragments. Fig. 5.1(c): Effect of active packaging on PLW (%) of MP orange 55

Fig. 5.1(d) and Table 5.2 represent the observations regarding PLW in MP tomato. Similarly this commodity had also responded in same manner for PLW parameter as was from apple, banana and orange. At 15 th day highest PLW value 2.60% was recorded in tomato slices treated with ethylene scavenger followed by moisture scavenger treated samples 2.43%. As in previous case chitosan coating was found very suitable to prevent PLW and minimum value 0.60% was recorded in treated tomato slices. Fig. 5.1(d): Effect of active packaging on PLW (%) of MP tomato Fig. 5.1(e) and Table 5.2 explain the observations regarding PLW in MP cauliflower. At 15 th day of storage, MP cauliflower showed highest PLW value 3.31% when treated with moisture scavenger followed by ethylene scavenger treated samples 2.93% and lowest value 1.13% was observed in chitosan coated cauliflower florets. There was comparatively less variation in PLW of cauliflower as compared to previous commodities studied. Fig. 5.1(e): Effect of active packaging on PLW (%) of MP cauliflower Fig. 5.1(f) and Table 5.2 express the observations regarding PLW in MP spinach and similar trend of PLW was observed for spinach too. Fig. 5.1(f): Effect of active packaging on PLW (%) of MP spinach PLW was recorded maximum in MP fruits and vegetables treated with scavengers whereas, samples coated with chitosan showed minimum weight loss throughout the storage. 56

Though MP samples were even stored at refrigerated conditions but there was loss in weight. PLW in MP samples might be correlated with increased cut surface area and water absorbing tendency of scavengers from surface of samples, as availability of moisture was higher on surface and interaction area also increased during minimal processing whereas, minimum PLW was observed in control samples of all commodities. Significant differences were observed among the treatments with respect to PLW of fresh-cut fruits and vegetables. A progressive increase in PLW during storage may also be due to high transpirational and respiratory losses. Thus, results demonstrated that AP treatments slow down the metabolism to give prolonged shelf-life. Moreover, water loss or transpiration is one of the major factors that affect the quality of the produce and so, the loss of firmness is usually associated to water loss, which is responsible by decreased turgor and crispness of fresh-cut fruits due to the absence of cuticle and exposure of internal tissues (Beaulieu and Gorny, 2002). The control samples of all the MP commodities, had shown the highest loss of texture and firmness whereas chitosan coating treatment presented the lowest loss of texture, firmness as presented in Fig. 5.11. Moreover, the efficacy of chitosan based edible antimicrobial coating against water loss in treated samples has shown lower weight loss than control. This is in agreement with Gustavo-Aguliar et al. (2008), who observed the effect of chitosan coatings on the overall quality of fresh-cut papaya and stated that the reduction in weight loss in fresh-cut papaya could be attributed to the barrier created by chitosan, which in turn reduced gas exchange and water loss. Worrell et al. (2002) reported the feature of protective coating is the lower rate of weight loss, i.e. a good film is that which establish a good difference in vapour pressure between the fruit and its surroundings. They further stated that chitosan is known to be hydrophilic in nature and only slight weight losses occur when used as a coating. Our results were in accordance with Olivas et al. (2007), who reported a reduction in moisture loss for aliginate coated Gala apples slices, as alginate coatings on apple slices proved to work effectively as water vapour barriers during storage at 5 C, thus coatings prevented the water loss by producing high relative humidity at the surface of sliced apples and thus reducing the gradient to the exterior. Wong et al. (1994) also reported that apple slices coated with carbohydrate/lipid bilayer film presented reduced water loss between 12 and 14 times when compared to the water loss suffered by uncoated apple slices in similar storage conditions. 5.2.1.2 Moisture content The effect of AP on moisture content (%) of MP fruits and vegetables during storage at refrigeration temperature presented in Fig. 5.2(a) for apple, 5.2(b) for banana, 5.2(c) for orange, 5.2(d) for tomato, 5.2(e) for cauliflower and 5.2(f) for spinach. The results summarized in Table 5.3 and 5.4 depict that with increase in storage duration upto 15 days at 57

5±1 C, the moisture content decreased in all the MP produces under AP treatments. However, control samples of all the MP fruits and vegetables observed lowest in moisture content on 15 th day of storage as comparative to other treatments. The incorporation of moisture absorbing sachet in main LDPE package as a type of active packaging was mainly aimed to prevent condensation within the package and subsequently to avoid any kind of mould or bacterial growth, which has been clearly illustrated from microbiological analysis data of all samples on 15 th day of storage. Moreover, it is submitted that moisture absorbing sachets were used to trigger the evapouration loss or moisture loss from any fruit or vegetable. Fig. 5.2(a) and Table 5.3 represent the observations regarding the changes in moisture content of MP apple.the results showed that the initial moisture content in apple was 83.48% which decreased during storage but was maximum (81.23%) in the chitosan coated samples followed by ethylene scavenger treated samples 80.97%, moisture scavenging treatment 80.73% and lowest 79.96% was observed in control samples at 15 th day. MP apple treated with chitosan coating and ethylene scavenger significantly reduce the decrease in moisture content but no significant differences were observed among the treatments. Fig. 5.2(a): Effect of active packaging on moisture content (%) of MP apple The observations regarding the changes in moisture content of MP banana are recorded and presented in Fig. 5.2(b) and Table 5.3.The perusal of data indicates that initial moisture content in banana was 73.80%. The maximum retention 71.52% was observed in the chitosan coated samples followed by ethylene scavenger treatment 71.50%, moisture scavenger 71.49%, O 2 scavenger 71.47%, control 71.45% and the lowest 71.42% was observed in CO 2 scavenger at 15 th day. Fig. 5.2(b): Effect of active packaging on moisture content (%) of MP banana 58

It is clear from the Fig. 5.2(c) and Table 5.3 that the initial moisture content in MP orange was 86.07% which decreased with storage and was found maximum (84.99%) in the samples treated with ethylene scavenger followed by samples treated with moisture scavenger and chitosan coated samples 84.88% and lowest 83.67% was recorded in control at 15 th day. AP treatments significantly reduce the decrease in moisture content in MP orange samples. Fig. 5.2(c): Effect of active packaging on moisture content (%) of MP orange Data containing the effects of different treatments on moisture content of tomato slices are given in Fig. 5.2(d) and Table 5.4. On the day of preparation i.e 0 day the highest moisture content (94.39%) was found which decreased during storage and maximum retention 92.67% was observed in the samples treated with ethylene scavenger followed by moisture scavenger 92.29%, chitosan treated samples 92.26%, O 2 scavenger 92.06%, CO 2 scavenger 91.88% and the lowest 91.40% was observed in control at 15 th day. AP treatments significantly reduce the decrease in moisture content in MP tomato slices. Fig. 5.2(d): Effect of active packaging on moisture content (%) of MP tomato Fig. 5.2(e) and Table 5.4 present the observations regarding the changes in moisture content of MP cauliflower and similar trend was attained. The results showed that the initial moisture content in cauliflower was 90.47%. On comparing the products with respect to application of active packaging treatments, chitosan coated samples retained more moisture 87.22% followed by O 2 scavenging treatment 84.60% and ethylene scavenger treated samples 84.45% and the lowest 84.24% was observed in control at 15 th day. Among the AP treatments chitosan coated samples significantly reduce the decrease in moisture content in MP cauliflower. 59

Fig. 5.2(e): Effect of active packaging on moisture content (%) of MP cauliflower Fig. 5.2(f) and Table 5.4 depict the observations regarding the changes in moisture content of MP spinach.the results showed that the initial moisture content in spinach was 90.20% which decreased during storage and the maximum retention 88.52% was observed in chitosan coated samples followed by ethylene scavenger 87.90%, moisture scavenger 87.64%, O 2 scavenger 87.32%, CO 2 scavenger 87.22% and the lowest 87.15% was observed in control at 15 th day. Chitosan coating, ethylene and moisture scavenger treated samples significantly reduce the decrease in moisture content in MP spinach. Fig. 5.2(f): Effect of active packaging on moisture content (%) of MP spinach Moisture content of all samples was found linearly decreasing with the advancement of storage period. There was comparatively lesser moisture loss with increasing storage duration in all AP treated samples. Maximum retention of moisture was observed in chitosan coated samples as it provide a barrier to moisture escaping and it was in quite agreement with the finding of Ronney (2005) who stated that a semi permeable membrane is formed on the surface of fruits and vegetables usually by coating with edible material that provide moisture barrier for helping to alleviate the problem of moisture loss from produce which leads to weight loss. Moreover, our results are in also agreement with those of Avena-Bustillos et al. (1997) who concluded that coatings and/or films significantly retain moisture content. El Gaouth et al. (1992b) and Baldwin et al. (1996) reported that moisture content was significantly decreased with increasing storage period. Reddy et al. (2011) investigated the effect of packaging on shelf-life of minimally processed green leafy vegetables (fenugreek and kirakasli) under different packaging material including muslin cloth, brown paper bags, LDPE, HDPE pouches and PET jars and observed that the green leafy vegetables packed in LDPE pouches retained higher moisture with good colour and texture at ambient storage for 60

three days. Parathy et al. (2003) observed that moisture loss is highly correlated with weight loss in wax apple stored at low temperature. 5.2.1.3 Total Soluble Solids (TSS) The observations regarding the effect of active packaging on TSS ( Brix) of MP fruits and vegetables during storage at refrigeration storage conditions are shown in Fig. 5.3(a) for apple, 5.3(b) for banana, 5.3(c) for orange, 5.3(d) for tomato and 5.3(e) for cauliflower and 5.3(f) for spinach and the results regarding these observations are presented in Table 5.5 and 5.6. Data related to the effects of AP treatments on changes in TSS content of MP apple during storage are presented in Fig. 5.3(a) and Table 5.5. On the day of preparation (0 day) of MP apple the initial TSS 12.17 Brix was found. There was an increasing trend in TSS content during storage. Chitosan coated samples exihibted less TSS content 13.17 Brix followed by ethylene scavenging treatment 13.33 Brix, moisture scavenger treated samples 13.47 Brix, samples treated with O 2 scavenger 13.6 Brix, CO 2 scavenging treatment 13.8 Brix and maximum 14.03 Brix was recorded in control samples at 15 th day. Significantly lower TSS was recorded in chitosan coating over all other treatments in MP apple. Fig. 5.3(a): Effect of active packaging on TSS ( Brix) of MP apple Fig. 5.3(b) and Table 5.5 express the observations regarding the changes in TSS content of MP banana.the results showed that the initial TSS in banana was 20.0 Brix and found lowest 23.93 Brix in the samples treated with ethylene scavenger followed by chitosan coated samples 24.0 Brix, moisture scavenger 24.27 Brix, CO 2 scavenger 24.47 Brix, O 2 scavenger 24.50 Brix and maximum 26.50 Brix was found in control samples at 15 th day. Fig. 5.3(b): Effect of active packaging on of TSS ( Brix) of MP banana 61

Fig. 5.3(c) and Table 5.5 represent the observations regarding the changes in TSS content of MP orange.the results showed that the initial TSS in orange was 9.12 Brix and found minimum 10.37 Brix in the chitosan coated samples followed by samples treated with ethylene scavenger treatment 10.48 Brix, moisture and O 2 scavenger 10.82 Brix, CO 2 scavenger 11.75 Brix and maximum 12.25 Brix was found in control samples at 15 th day of storage. AP treatments significantly reduce the increase in TSS in MP orange. Fig. 5.3(c): Effect of active packaging on TSS ( Brix) of MP orange Fig. 5.3(d) and Table 5.6 present the observations regarding the changes in TSS content of MP tomato.the results showed that the initial TSS in tomato was 4.0 Brix and found lowest 4.83 Brix in the chitosan coated samples followed by samples treated with ethylene scavenger treatment 4.97 Brix, O 2 scavenger 5.17 Brix, moisture scavenger 5.2 Brix and highest 5.4 Brix was recorded in CO 2 scavenger and control samples at 15 th day. Fig. 5.3(d): Effect of active packaging on TSS ( Brix) of MP tomato Fig. 5.3(e) and Table 5.6 depict the observations regarding the changes in TSS content of MP cauliflower.the results showed that the initial TSS in cauliflower was 5.17 Brix and observed lowest 5.73 Brix in chitosan coated samples followed by samples treated with ethylene scavenger treatment 5.8 Brix, moisture scavenger 5.9 Brix, O 2 scavenger 5.93 Brix, CO 2 scavenger 5.97 Brix and highest 6.1 Brix was found in control samples at 15 th day. Fig. 5.3(e): Effect of active packaging on TSS ( Brix) of MP cauliflower 62

Similar observations regarding the changes in TSS content were also achieved for MP spinach and are presented in Fig. 5.3(f) and Table 5.6. The results showed that the initial TSS in spinach was 4.03 Brix which increased during storage and registered lowest 4.87 Brix in chitosan coated samples followed by samples treated with ethylene scavenger treatment 4.97 Brix, moisture scavenger and O 2 scavenger 5.3 Brix, CO 2 scavenger 5.63 Brix and maximum 5.73 Brix was found in control samples at 15 th day. Fig. 5.3(f): Effect of active packaging on TSS ( Brix) of MP spinach TSS increased with increasing period of storage and the control samples had maximum TSS. Significantly lower TSS was observed in chitosan coated samples which was on par with ethylene scavenging treatment. The general rise in TSS of fruits may be due to hydrolysis of polysaccharides i.e. conversion of starch into sugars by metabolic activities and loss of water from fruit surface. Among all the treatments, coated fruits and vegetables exhibited minimum rise in TSS followed by ethylene scavenger, moisture scavenger, O 2 scavenger and CO 2 scavenger, all the scavengers were equally effective in reducing the increase in TSS. The results of the present investigation are in accordance with the previously reported results, Hussain et al. (2005) observed that TSS was significantly increased by increasing storage period. Bico et al. (2009) supported our findings who investigated the effect of chemical dip combined with controlled atmosphere on the quality of fresh-cut banana and found that treated samples presented the lower increase in TSS content during storage at 5 C by suppressing the respiration rate and ripening process in minimally processed banana. Oms-Oliu et al. (2007) also found the similar trend in TSS in fresh-cut melon preserved at 5 C by modified atmosphere packaging for 35 days. On the other hand Bett et al. (2001) stored cut Gala apples at 1 C for 14 days and did not find changes in TSS. Contrary to our findings Li et al. (2011) reported reductions in TSS levels of fruits during storage. 5.2.1.4 Titratable Acidity The observations regarding the effect of active packaging treatments on titratable acidity (%) of MP fruits and vegetables at refrigeration temperature storage condition are presented in Fig. 5.4 (a-f) and the results summarized in Table 5.7 and 5.8. 63

Fig. 5.4(a) and Table 5.7 represent the observations regarding the changes in titratable acidity of MP apple. On the day of preparation i.e 0 day the initial acidity 0.237% in apple was recorded which decreased during storage and was found maximum 0.12% in the chitosan coated samples followed by samples treated with ethylene scavenger 0.113%, samples treated with O 2 scavenging treatment 0.093%, moisture scavenging treatment 0.09%, samples treated with CO 2 scavenger 0.08% and lowest 0.073% was observed in control samples at 15 th day. Titratable acidity of all samples was found decreasing with the advancement of storage period and maximum decrease was observed in control samples. Role of AP treatment in retention of acidity level was good enough except CO 2 scavenger treated samples. Fig. 5.4(a): Effect of active packaging on titratable acidity (%) of MP apple Similar decreasing trend was also attained for MP banana and presented in Fig. 5.4(b) and Table 5.7. Initial titratable acidity 0.231% was recorded in banana and found maximum 0.161% in banana slices treated with ethylene scavenger followed by chitosan coated slices 0.158%, slices treated with O 2 scavenger 0.154%, moisture scavenger treated slices 0.152% whereas, lowest and similar 0.148% values were observed in CO 2 scavenger treated slices and control samples at 15 th day. Fig. 5.4(b): Effect of active packaging on titratable acidity (%) of MP banana Fig. 5.4(c) and Table 5.7 represent the observations regarding the changes in titratable acidity of MP orange.the results showed that the initial acidity in orange was 1.26% which decreased during storage. On 15 th day maximum and similar value of titratable acidity 0.887% was found in the samples coated with chitosan and samples treated with ethylene and moisture scavengers followed by samples treated with O 2 scavenger 0.84%, and the lowest 0.747% was recorded in the samples treated with CO 2 scavenger and control samples. 64

Fig. 5.4(c): Effect of active packaging on titratable acidity (%) of MP orange Fig. 5.4(d) and Table 5.8 depict the observations regarding the changes in titratable acidity of MP tomato. The results showed that the initial acidity in tomato was 1.12% and found maximum 0.77% in chitosan coated samples followed by samples treated with ethylene scavenger 0.63% whereas, moisture and O 2 scavengers registered similar values 0.56%, and lowest but similar values 0.49% were exhibited by CO 2 scavenger treated and control samples at 15 th day. Fig. 5.4(d): Effect of active packaging on titratable acidity (%) of MP tomato Fig. 5.4(e) and Table 5.8 depict the observations regarding the changes in titratable acidity of MP cauliflower. The results showed that the initial acidity in cauliflower was 0.094% which decreased during storage and recorded maximum 0.079% in the samples treated with ethylene scavenger followed by chitosan coating 0.078% whereas, moisture, O 2 and CO 2 scavengers exhibited identical values 0.077% and lowest retention 0.075% was observed in control samples at 15 th day. AP treatments significantly reduce the decrease in titratable acidity in MP cauliflower. Fig. 5.4(e): Effect of active packaging on titratable acidity (%) of MP cauliflower Fig. 5.4(f) and Table 5.8 represent the observations regarding the changes in titratable acidity of MP spinach. Data in Table 5.8 indicates that the initial titratable acidity in spinach was 0.093%. Samples treated with chitosan coating and ethylene scavenging treatment had 65

similar and higher 0.079% acidity content followed by moisture scavenging treatment 0.077% whereas, O 2 and CO 2 scavenger possess similar values 0.076%, and lowest 0.075% was recorded in control samples at 15 th day. Fig. 5.4(f): Effect of active packaging on titratable acidity (%) of MP spinach Titratable acidity of MP fruits and vegetables decreased with increasing period of storage, this progressive decrease in acidity was another important factor showing the loss of fruit quality. Active packaging treatments especially chitosan coating, ethylene and moisture scavengers significantly decreased the reduction in acidity during storage. Chitosan treated fresh-cut fruits and vegetables recorded significantly higher titratable acidity followed by ethylene and moisture scavenger, which was on par with O 2 and CO 2 scavenger treatments. Our results are in agreement with Rathore et al. (2007) who reported a decrease in acidity which may be due to the conversion of acids into sugars and their further utilisation in metabolic process in the fruits during ripening process. Furthermore, Olivas et al. (2007) also found the decrease in titratable acidity of minimally processed cut Gala apples treated with alginate coatings when stored at 5 C in 85% RH. Similarly, Bico et al. (2009) also reflected the same decreasing trend of acidity in fresh-cut banana when stored at 5 C. This was probably due to utilization of organic acids as substrates for the enzymatic reactions in respiration during storage. 5.2.1.5 Ascorbic acid The observations regarding the effect of active packaging on MP fruits and vegetables on ascorbic acid content (mg/100g) during storage are presented in Fig 5.5(a) for apple, 5.5(b) for banana, 5.5(c) for orange, 5.5(d) for tomato, 5.5(e) for cauliflower and 5.5(f) for spinach. A gradual decrease in the ascorbic acid was observed in all AP treatments for all the MP commodities kept at refrigeration temperature and the results are summarized in Table 5.9 and 5.10 given in appendices. Fig. 5.5(a) and Table 5.9 present the observations regarding the changes in ascorbic acid of MP apple. Initial ascorbic acid content for apple was found to 7.36 mg/100g. When comparing the mean values, maximum retention 6.09 mg/100g of ascorbic content was observed in the samples treated with ethylene scavenger followed by chitosan coated samples 6.03 mg/100g, samples treated with moisture scavenger 5.99 mg/100g, O 2 scavenger 5.78 mg/100g, CO 2 scavenger 5.54 mg/100g and the minimum 5.10 mg/100g was observed in control samples. AP treatments significantly reduce the decrease in ascorbic acid content. 66

Fig. 5.5(a): Effect of active packaging on ascorbic acid (mg/100g) of MP apple Fig. 5.5(b) and Table 5.9 represent the observations regarding the changes in ascorbic acid of MP banana. The ascorbic acid content for banana at 0 day was highest and found to be 10.0 mg/100g. When comparing the mean values, maximum retention 7.96 mg/100g of ascorbic content was observed in the samples treated with chitosan followed by samples treated with ethylene scavenger 7.64 mg/100g, moisture scavenger 7.60 mg/100g, O 2 scavenger 7.54 mg/100g, CO 2 scavenger 7.24 mg/100g and the minimum 7.00 mg/100g was observed in control samples. Fig. 5.5(b): Effect of active packaging on ascorbic acid (mg/100g) of MP banana Fig. 5.5(c) and Table 5.9 depict the observations regarding the changes in ascorbic acid of MP orange. Initial ascorbic acid content for orange on 0 day was found to be 30.0 mg/100g. When comparing the mean values, samples treated with ethylene scavenger retained maximum 25.67 mg/100g ascorbic content followed by chitosan coated samples 25.14 mg/100g, moisture scavenging treatment 24.79 mg/100g, O 2 scavenging treatment 24.02 mg/100g, CO 2 scavenging treatment 22.16 mg/100g and the minimum 20.65 mg/100g was observed in control samples. AP treatments significantly reduce the decrease in ascorbic acid content. Fig. 5.5(c): Effect of active packaging on ascorbic acid (mg/100g) of MP orange 67

Fig. 5.5(d) and Table 5.10 express the observations regarding the changes in ascorbic acid of MP tomato. On 0 day 13.55 mg/100g ascorbic acid content for tomato was recorded. When comparing the mean values, similar trend of ascorbic acid was observed for tomato too. Howerver, maximum 11.59 mg/100g and minimum 9.76 mg/100g retention of ascorbic acid was observed in samples treated with chitosan coating and control respectively. AP treatments significantly reduce the decrease in ascorbic acid content. Fig. 5.5(d): Effect of active packaging on ascorbic acid (mg/100g) of MP tomato Fig. 5.5(e) and Table 5.10 depict the observations regarding the changes in ascorbic acid of MP cauliflower. Initial ascorbic acid content for cauliflower was found to be 44.72 mg/100g. When comparing the mean values, maximum retention 39.39 mg/100g of ascorbic content was observed in the samples treated with chitosan coating followed by samples treated with ethylene scavenger 39.30 mg/100g, moisture scavenger 38.91 mg/100g, O 2 scavenger 38.78 mg/100g, CO 2 scavenger 38.53 mg/100g and the minimum 38.13 mg/100g was observed in control samples. AP treatments except CO 2 scavenger significantly reduce the decrease in ascorbic acid content. Fig. 5.5(e): Effect of active packaging on ascorbic acid (mg/100g) of MP cauliflower Fig. 5.5(f) and Table 5.10 present the observations regarding the changes in ascorbic acid of MP spinach. Initial ascorbic acid content for spinach was found to be 36.71 mg/100g. At 15 th day of storage, maximum retention 27.76 mg/100g of ascorbic content was observed in chitosan coated samples followed by samples treated with ethylene scavenger 27.65 mg/100g, moisture scavenger 27.48 mg/100g whereas, O 2 and CO 2 scavenger possessed similar 26.69 mg/100g values and control samples exhibited minimum 24.51 mg/100g. AP treatments significantly reduce the decrease in ascorbic acid content. The retention of ascorbic acid content in all the control samples of MP produces was minimum, and 68

significantly higher retention was observed in case of chitosan coated commodities followed by ethylene, moisture, O 2 and CO 2 scavengers among the treatments of AP. Fig. 5.5(f): Effect of active packaging on ascorbic acid (mg/100g) of MP spinach Decrease in ascorbic acid might be due to enzymatic oxidation of L-ascorbic acid to dehydroascorbic acid and higher ascorbic acid retention at low temperature could be attributed to lower rate of physiological processes. Oxidation of ascorbic acid may be caused by several factors including exposure to oxygen, metals, light, heat and alkaline ph (Sritananan et al., 2005).The reason for high ascorbic acid content in coated fruits may be due to slow ripening rate of chitosan treated fruit. This is in agreement with (Srinivasa et al., 2002) who reported that coatings served as a protective layer and control the permeability of O 2 and CO 2. Soliva-Fortuny and Martin-Belloso (2003) studied the effect of packaging atmospheres on the biochemical changes in fresh-cut conference pears cubes packed in plastic bags in refrigerated conditions for 3 weeks and stated that ascorbic acid content decreased with time as a result of availability of O 2 in the package headspace. Soliva-Fortuny et al. (2004) also support our findings and reported a similar decreasing trend in ascorbic acid content during storage of fresh-cut apples. Further, Lee and Kader (2000) also observed the similar results i.e. decreased ascorbic acid content in apples, sweet peppers and strawberries when stored in atmosphere high in CO 2. Hussein et al. (2000) also reported that in broccoli and green pepper ascorbic acid decreased after 10 days of storage. 5.2.1.6 Pectin Pectin content in the form of calcium pectate (%) was determined in case of MP apple, banana and orange (fruits). Observations regarding the effect of AP treatments on pectin are given in Fig 5.6 (a-c). Progressive decrease in the pectin content was observed in all the treatments during storage and is presented in Table 5.11 as given in appendices. The perusal of data indicates that intial pectin content for apple 1.09%, banana 2.8% and orange 2.12%. Fig. 5.6(a) and Table 5.11 present the observations regarding the changes in pectin content of MP apple. When comparing the mean values, maximum retention 0.89% of pectin was observed in MP apple when coated with chitosan followed by the samples treated with ethylene scavenger 0.88%, moisture scavenger 0.85%, O 2 scavenger 0.81%, CO 2 scavenger 69

0.77% and the minimum 0.75% was observed in control samples. AP treatments significantly reduce the decrease in pectin content in MP apple. Fig. 5.6(a): Effect of active packaging on pectin (%) of MP apple Fig. 5.6(b) and Table 5.11 express the observations regarding the changes in pectin content of MP banana. When comparing the mean values, maximum retention 2.20% of pectin was observed in chitosan coated banana slices followed by the samples treated with ethylene scavenger 2.14%, moisture scavenger 2.08%, O 2 scavenger 2.04%, CO 2 scavenger 1.98% and the minimum 1.83% was observed in control samples. Fig. 5.6(b): Effect of active packaging on pectin (%) of MP banana Fig. 5.6(c) and Table 5.11 present the observations regarding the changes in pectin content of MP orange. On 15 th day, maximum pectin content was observed in samples treated with ethylene scavenger 1.03% followed by moisture scavenging treatment 1.01%, chitosan coated samples 0.99%, samples treated with O 2 scavenger 0.87%, CO 2 scavenger 0.84% and minimum was observed in control samples 0.70%. Chitosan coating, ethylene and moisture scavengers significantly reduce the decrease in pectin content in MP orange. Fig. 5.6(c): Effect of active packaging on pectin (%) of MP orange 70

The decrease in pectin may be attributed to degradation of pectic polysaccharides. Pectin content differed significantly between the AP treatments and was observed higher in chitosan treated MP commodities followed by ethylene, moisture O 2 and CO 2 scavengers whereas, the control fruits recorded significantly lower pectin content. Our results are in line with those of Kashappa and Hyun, (2006) who observed that better retention of firmness in coated fruits as compared with untreated ones can be explained by retarded degradation of insoluble protopectins to the more soluble pectic acid and pectin during fruit ripening as depolymerisation or shortening of the chain length of pectin substances occurs with an increase in pectin-esterase and polygalacturonase activities. The decrease in pectin content in all the commodities during storage might be the result of pectolytic enzymes activity on natural pectin in the fruits (Nara et al., 2001). Toivonen and Brummell (2008) studied the texture related enzymes and found that the release of pectinolytic and proteolytic enzymes is expected after cutting due to degradation of cell wall, both the enzymes diffuse to the interior of the tissue and act upon their substrates (pectin and proteins), hence damaging the structure. Bhaskar-Reddy et al. (2000) evaluated the effect of chitosan coatings on tomatoes and suggested that chitosan had a protective effect against loss of mechanical strength of the fruit. 5.2.1.7 Total sugars Total sugar content (%) was analysed in all the MP commodities of fruits and vegetables except spinach as it does not contain sugars and the observations with respect to the total sugars content of MP fruits and vegetables for different treatments during refrigerated storage are presented in Fig. 5.7(a) for apple, 5.7(b) for banana, 5.7(c) for orange, 5.7(d) for tomato, 5.7(e) for cauliflower and the results presented in Table 5.13 and 5.14 given in appendices. A progressive increase was observed in total sugar content during storage. Fig. 5.7(a) and Table 5.12 reveal the observations regarding the changes in total sugar content of MP apple. The results showed that the initial total sugar content in apple was 9.97% which increased during storage and minimum 12.27% was observed in the chitosan treated samples followed by moisture scavenger 12.35%, ethylene scavenger 12.53%, O 2 scavenger 12.54%, in CO 2 scavenger 12.83% and maximum 13.68% increase was recorded in control samples at 15 th day. AP treatments significantly reduce the increase in total sugar content in MP apple. 71

Fig. 5.7(a): Effect of active packaging on total sugars (%) of MP apple Fig. 5.7(b) and Table 5.12 present the observations regarding the changes in total sugar content of MP banana. The initial total sugar content in banana at 0 day was 18.0% which increased during storage and found minimum 20.67% in chitosan coated samples followed by samples treated with ethylene scavenger 20.93%, moisture scavenging treatment 21.07%, O 2 scavenging treatment 21.13%, samples treated with CO 2 scavenger 21.27% and maximum increase 22.0% was recorded in control samples at 15 th day. AP treatments significantly reduce the increase in total sugars in MP banana. Fig. 5.7(b): Effect of active packaging on Total sugars (%) of MP banana Fig. 5.7(c) and Table 5.12 depict the observations regarding the changes in total sugar content of MP orange. The results showed that the initial total sugar content in orange fragments was 8.33% and at 15 th day samples treated with ethylene scavenger exhibited minimum 9.17% increase followed by samples treated with moisture scavenger 9.23%, chitosan coated samples 9.33% and O 2 scavengers 9.40%, samples treated with CO 2 scavenger possessed 9.50% value and maximum 9.93% increase was recorded in control samples. AP treatments significantly reduce the increase in content of total sugars in MP orange. Fig. 5.7(c): Effect of active packaging on total sugars (%) of MP orange 72

Fig. 5.7(d) and Table 5.13 express the observations regarding the changes in total sugar content of MP tomato. The results showed that the initial total sugar content in tomato was 1.63% and minimum 1.91% increase was observed in the chitosan treated samples followed by ethylene scavenging treatment 1.92%, moisture scavenging treatment 1.93%, samples treated with O 2 scavenger 1.96% and the samples treated with CO 2 scavenger exhibited maximum 1.99% increase. On the other hand control samples leads to lower 1.86% total sugar content than AP treatments at 15 th day. Fig. 5.7(d): Effect of active packaging on total sugars (%) of MP tomato Data pertaining to the effect of different of active packaging on total sugar content of MP cauliflower during storage (Fig. 5.7(e) and Table 5.13) depict that at 0 day initial total sugar content in cauliflower was 1.89% which increased during storage in all the treatments. Chitosan coated samples showed minimum 2.07% increase followed by ethylene scavenging treatment 2.13%, samples treated with CO 2 scavenger 2.12%, samples treated with moisture and O 2 scavenger exhibited similar 2.15% change and maximum 2.17% increase was recorded in control samples at 15 th day. Non significant increase was observed among AP treatments in MP cauliflower. Fig. 5.7(e): Effect of active packaging on total sugars (%) of MP cauliflower The increased total sugar content of MP fruits and vegetables could be due to the conversion of starch and organic acids into sugars. Significant differences were observed in the treated samples with respect to control ones of MP fruits and vegetables and significantly higher total sugar content was observed in control samples followed by commodities treated with CO 2, O 2, moisture and ethylene scavengers, whereas; control samples in case of tomato present lower total sugar content than other treatments at later storage periods (15 th day) 73

which could be due to the utilization of sugars in respiration and other metabolic activities as well as the utilization of sugars by microorganisms for their food. AP treatments significantly reduce the increase in total sugar content in tomato slices. Sgroppo et al. (2010) found that minimally processed sweet-potatoes when packed under refrigerated storage showed increase in total sugar content probably due to ripening and conversion of starch into sugar. Our results are in agreement with Karacay and Ayhan (2010) who reported a significant increase in total sugar content in minimally processed grapefruit segments packaged under modified atmosphere. Gupta and Jawandha (2010) reported a gradual increase in reducing sugar in peaches during storage. 5.2.1.8 Total chlorophyll Total chlorophyll pigment (mg/100g) was analyzed in case of green leafy vegetable i.e. MP spinach and present in Fig. 5.8 (a). In this experiment, AP treatments resulted in a substantial retention of chlorophyll content of MP spinach during storage under the refrigerated storage conditions. The initial total chlorophyll content in MP spinach was found to be 5.9 mg/100g which degrades during storage and maximum 4.19 mg/100g retention of total chlorophyll content was observed in chitosan coated samples followed by the samples treated with ethylene scavenger 4.17 mg/100g, moisture scavenger 4.03 mg/100g, O 2 scavenger 4.00 mg/100g, CO 2 scavenger mg/100g and control samples retained minimum 3.17 mg/100g. Fig. 5.8(a): Effect of AP on total chlorophyll (mg/100g) of MP spinach All the treatments and their interactions were statistically different at 5% level with respect to chlorophyll retention. This suggested that AP treatments have proven beneficial for chlorophyll retention particularly; the chitosan coating may have played a predominant role in chlorophyll retention. This was because the chloroplasts in green immature fruits and vegetables generally lose chlorophyll on ripening and change into chromoplasts that contain carotenoid pigments. Our results are supported by the work of Ibrahim et al. (2005) who investigated chlorophyll degradation in shredded cabbage packed under different packaging films (PP, LDPE, HDPE) and control samples in polystyrene tray with PVC cling wrap at 5±1 C and 90-95% RH and decreased chlorophyll content was observed in all the packaging 74

films whereas, control showed higher degradation as compared to films, which may be due to higher chlorophyllase activity, respiration rate and ethylene production in shredded cabbage during storage. Our results are in accordance with those of Pandrangi and LaBorde (2004) who observed progressive degradation in chlorophyll content of spinach throughout storage at 4, 10 and 20 C, which occurred more rapidly at higher temperatures. Similar trend in chlorophyll was also observed by Artes-Hernandez et al. (2008) in minimally processed spinach leaves under UV-C radiation stored at 5 and 8 C for 13 days. Under all the AP treatments, when the in-pack O 2 was being consumed, a gradual increase in the CO 2 levels was taking place. Under these conditions, the decrease in the chlorophyll content is largely influenced by higher levels of in-pack O 2 alone. These results are in agreement with the earlier reported observations of Moretti et al. (2003) where an initial decrease in the chlorophyll content was observed for minimally processed green collards under the influence of high or ambient levels of O 2. As the storage period progressed CO 2 build up took place inside the film packages leading to stabilization in the chlorophyll retention levels in the storage conditions. 5.2.1.9 Tannins, Total phenols and Polyphenol oxidase activity The observations regarding the effect of active packaging on tannins (mg/100g), total phenols (mg/100g) and enzymatic browning in terms of PPO activity, were recorded during storage at refrigerated storage temperature and the results summarized in the Table 5.15 represent the tannins and total phenols in fruits, Table 5.16 total phenols in vegetables whereas Table 5.17 and 5.18 present the results of browning for fruits and vegetables respectively as given in appendices. Tannin content was analyzed in case of apple and banana and present in Fig. 5.91(a) and 5.91(b) whereas total phenols was studied in the remaining commodities (orange, tomato, cauliflower and spinach) and present in Fig 5.91(c), 5.91(d), 5.91(e) and 5.91(f) as these are good source of phenols and do not contain good amount of tannin. Fig. 5.91(a) and Table 5.15 present the observations regarding the changes in tannin content of MP apple. The results show that the initial tannin content in apple was 7.12 mg/100g which decreased with the advancement of storage and at 15 th day maximum 4.72 mg/100g retention was observed in the chitosan coated samples followed by samples treated with ethylene and moisture scavenger 4.52 mg/100g, O 2 scavenger 4.42 mg/100g, CO 2 scavenger 4.34 mg/100g and maximum 3.93 mg/100g decrease was recorded in control samples. AP treatments significantly reduce the decrease in tannin content in apple slices. 75

Fig. 5.91(a): Effect of active packaging on tannins (mg/100g) of MP apple Fig. 5.91(b) and Table 5.15 depict the observations regarding the changes in tannins of MP banana. The results show that the initial tannin content in banana was 2.93 mg/100g which decreased during storage and was maximum 1.39 mg/100g in the chitosan coated samples followed by samples treated with ethylene scavenger 1.35 mg/100g, moisture scavenger 1.29 mg/100g, O 2 and CO 2 scavenger registered similar 1.20 mg/100g values and control samples exhibited maximum (0.91 mg/100g) decrease at 15 th day. AP treatments significantly reduce the decrease in tannin content in banana slices. Fig. 5.91(b): Effect of active packaging on tannins (mg/100g) of MP banana Fig. 5.91(c) and Table 5.15 reveal the observations regarding the changes in total phenols of MP orange. The results show that the initial phenolic content in orange was 118.83 mg/100g and maximum 88.21 mg/100g retention was observed in the chitosan coated samples followed by samples treated with ethylene scavenger 87.63 mg/100g, moisture scavenger 84.89 mg/100g, O 2 scavenger 84.17 mg/100g, CO 2 scavenger 81.26 mg/100g and the control samples exhibited minimum 78.32 mg/100g retention at 15 th day. AP treatments significantly reduce the decrease in total phenolic content in orange fragments. Fig. 5.91(c): Effect of active packaging on total phenols (mg/100g) of MP orange 76

Fig. 5.91(d) and Table 5.16 present the observations regarding the changes in total phenols of MP tomato. The results show that the initial phenolic content in tomato was 38.94 mg/100g and chitosan coated samples possessed the highest 19.28 mg/100g amount followed by samples treated with ethylene scavenger 19.02 mg/100g, moisture scavenger 18.85 mg/100g, O 2 scavenger 18.04 mg/100g, CO 2 scavenger 17.06 mg/100g and control samples possessed lowest 10.65 mg/100g amount at 15 th day. AP treatments significantly reduce the decrease in total phenolic content in tomato slices. Fig. 5.91(d): Effect of active packaging on total phenols (mg/100g) of MP tomato Fig. 5.91(e) and Table 5.16 express the observations regarding the changes in total phenols of MP cauliflower. The results show that the initial phenolic content in cauliflower was 61.84 mg/100g and at 15 th day highest retention 41.80 mg/100g was observed in the chitosan coated samples followed by samples treated with ethylene scavenger 41.24 mg/100g, moisture scavenger 40.63 mg/100g, O 2 scavenger 39.80 mg/100g, CO 2 scavenger 38.96 mg/100g and lowest 38.53 mg/100g retention was exhibited in control samples. AP treatments except O 2 and CO 2 scavenger significantly reduce the decrease in total phenolic content in MP cauliflower. Fig. 5.91(e): Effect of active packaging on total phenols (mg/100g) of MP cauliflower Fig. 5.91(f) and Table 5.16 depict the observations regarding the changes in total phenols of MP spinach. The results show that the initial phenolic content in spinach was 113.33 mg/100g. Among the AP treatments chitosan coated samples exhibited the highest 87.94 mg/100g amount and control samples the lowest 73.81 mg/100g at 15 th day. AP treatments significantly reduce the decrease in total phenolic content in MP spinach. 77

Fig. 5.91(f): Effect of active packaging on total phenols (mg/100g) of MP spinach The control samples showed a decrease in tannin and phenolic content during storage, while treated fruits and vegetables produced the lowest decrease. Application of active packaging techniques on MP fruits and vegetables were found to be effective in reducing the decrease in tannin/total phenolic content during storage. All the treatments and their interactions were observed to produce a significant effect on the tannins/phenolic content of the samples. Moreover, PPO activity (units/g fr.wt./h) was studied in case of MP fruits and vegetables. These parameters are interrelated with each other, during storage tannin and phenolic content decreases and thereby increase in polyphenol oxidase (PPO) activity i.e. enzymatic browning increases with the advancement of storage and initially the PPO activity was recorded in apple 10.17 units/g fr.wt./h, 10.91 units/g fr.wt./h in banana, 1.56 units/g fr.wt./h in orange, 1.83 units/g fr.wt./h in tomato, 0.53 units/g fr.wt./h in cauliflower and 1.91 units/g fr.wt./h in spinach. Fig. 5.92(a) and Table 5.17 present the observations regarding the changes in polyphenol oxidase (PPO) activity of MP apple. The results show that PPO activity increased during storage and found minimum 15.13 units/g fr.wt./h in apple slices treated with ethylene scavenger followed by chitosan coated samples 15.58 units/g fr.wt./h, samples treated with moisture scavenger 15.60 units/g fr.wt./h, O 2 scavenger 15.71 units/g fr.wt./h, CO 2 scavenger 16.05 units/g fr.wt./h and maximum 17.58 units/g fr.wt./h was recorded in control samples at 15 th day. AP treatments significantly reduce the increase in PPO activity in MP apple. Fig. 5.92(a): Effect of active packaging on browning (units/g fr.wt./h) of MP apple 78

Fig. 5.92(b) and Table 5.17 express the observations regarding the changes in polyphenol oxidase (PPO) activity of MP banana. The results show that PPO activity increased during storage and found minimum 15.0 units/g fr.wt./h in chitosan coated banana slices followed by samples treated with ethylene scavenger 15.02 units/g fr.wt./h, moisture scavenger 15.07 units/g fr.wt./h, O 2 scavenger 15.36 units/g fr.wt./h, CO 2 scavenger 15.61 units/g fr.wt./h and the maximum 15.9 units/g fr.wt./h was recorded in control samples at 15 th day. AP treatments except CO 2 scavenger having significantly lower PPO activity in MP banana. Fig. 5.92(b): Effect of active packaging on browning (units/g fr.wt./h) of MP banana Fig. 5.92(c) and Table 5.17 depict the observations regarding the changes in polyphenol oxidase (PPO) activity of MP orange. The results show that chitosan coated samples resulted in lower 2.19 units/g fr.wt./h PPO activity followed by samples treated with O 2 scavenger 2.23 units/g fr.wt./h, ethylene scavenger 2.26 units/g fr.wt./h, moisture scavenger 2.33 units/g fr.wt./h, CO 2 scavenger 2.42 units/g fr.wt./h and highest 2.49 units/g fr.wt./h activity was recorded in control samples at 15 th day. AP treatments significantly reduce the increase in PPO activity in orange fragments. Fig. 5.92(c): Effect of active packaging on browning (units/g fr.wt./h) of MP orange Fig. 5.92(d) and Table 5.18 present the observations regarding the changes in polyphenol oxidase (PPO) activity of MP tomato. The samples treated with O 2 scavenger were reported in lower 2.48 units/g fr.wt./h PPO activity followed by the samples treated with ethylene scavenger 2.62 units/g fr.wt./h, chitosan coated samples 2.63 units/g fr.wt./h, moisture scavenger 2.66 units/g fr.wt./h, CO 2 scavenger 2.93 units/g fr.wt./h and the highest value 3.35 units/g fr.wt./h was recorded in control samples at 15 th day. AP treatments significantly reduce the increase in PPO activity in tomato slices. 79

Fig. 5.92(d): Effect of active packaging on browning (units/g fr.wt./h) of MP tomato Fig. 5.92(e) and Table 5.18 depict the observations regarding the changes in polyphenol oxidase (PPO) activity of MP cauliflower. The results show at 15 th day similar and minimum 0.80 units/g fr.wt./h PPO activity was exhibited by the samples treated with chitosan and O 2 scavenger followed by samples treated with ethylene scavenger 0.86 units/g fr.wt./h, moisture scavenger 0.88 units/g fr.wt./h, CO 2 scavenger 0.90 units/g fr.wt./h and maximum activity 0.96 units/g fr.wt./h was recorded in control samples. AP treatments significantly reduce the increase in PPO activity in florets of cauliflower. Fig. 5.92(e): Effect of active packaging on browning (units/g fr.wt./h) of MP cauliflower Fig. 5.92(f) and Table 5.18 express the observations regarding the changes in polyphenol oxidase (PPO) activity of MP spinach. Control samples showed significantly higher 2.63 units/g fr.wt./h PPO activity than other AP treatments and chitosan coated samples reported significantly lower 2.25 units/g fr.wt./h PPO activity. Fig. 5.92(f): Effect of active packaging on browning (units/g fr.wt./h) of MP spinach The browning reaction results primarily from the action of enzyme polyphenol oxidase on phenolic compounds in the plant tissue to form o-quinones, which in turn polymerize to form dark pigments and this marked increase in PPO activity level could be associated with decreased tannin and total phenolic content and disappearance of astringency 80

in fruits and vegetables during storage. Slow increase in PPO activity at low temperature could be attributed to reduced metabolic activities and delayed ripening. Active packaging techniques slowed down the increase in activity of PPO in MP fruits and vegetables significantly. Oxidation of phenolic substrates by polyphenol oxidase (PPO) is believed to be a major cause of browning of many fruits and vegetables, including banana (Nguyen et al., 2003) they also reported the correlation between decrease in total phenolic concentration and increase in PPO activity. Our findings corroborate with that of Pilar-Cano et al. (1997) who suggested that the degree of browning in MP fruits and vegetables can be correlated with PPO activity and tannin content. Similar to our findings, Bico et al. (2009) observed a decrease in total phenolic content and increase in PPO activity in minimally processed banana during storage for 5 days at 5 C, control samples presented higher PPO activity and lower toal phenolic content as compared to chemical dips. Li et al. (2011) synthesized a nano packaging by coating polyvinyl chloride (PVC) film with nano-zno powder, investigated its effect on quality of fresh-cut Fuji apple at 4 C for 12 days and found that nanopackaging significantly reduced PPO activities which leads to browning, can catalyse the hydroxylation of monophenols to o-diphenols and the oxidation of o-quinones. MP fruits treated with antimicrobial film resulted in the lowest PPO activity among all treatments during all the storage conditions. Furthermore, the high PPO activity in control samples during storage is associated with low level of tannin content probably may be due to the unprotected state of the sample towards enzymatic reactions. Rocha and Morais (2001) found L* values of Jonagored apple cubes during storage at 4 C to be moderately correlated to PPO activity, while Lee et al. (2003) suggested that peach cultivars having higher PPO activity showed a higher rate of browning and vice versa. Pen and Jiang (2003) confirmed the inhibitory effect of chitosan solution on polyphenol oxidase that increases at higher concentrations of the chitosan solution. He et al. (2008) investigated the effect of sodium chlorite (SC) on polyphenol oxidase (PPO) and its substrate chlorogenic acid (CA) and found that the browning reaction of CA (1.0 mm) catalyzed by PPO (33 U/ml) was significantly inhibited by 1.0mM SC at ph 4.6. 5.2.1.10 Texture and Firmness Texture and firmness testing was conducted using texture analyzer to predict the force required to cut and to puncture the samples with blade type and cylindrical type probes respectively and the required shear force is mentioned in gram (g). The observations regarding the effect of AP on texture and firmness (force, g) of MP fruits and vegetables using texture analyzer are shown in Fig. 5.10 (a-e) and Fig. 5.10 (f-j) 81

respectively. A progressive and significant decrease was observed in the texture and firmness among the MP fruits and vegetables and are presented in Table 5.20, 5.21 and 5.22 as given in appendices. Figs. 5.10 (a and b) present the observations regarding changes in texture (Table 5.19) and firmness (Table 5.20) in apple slices. In the present study the intial value for texture and firmness for apple was observed 1980.8 and 146.7 g which decreased during storage and it was found that at 15 th day the chitosan coated apple slices had highest texture and firmness value (1683.6 and 121.8 g) of shear strength followed by samples treated with ethylene scavenger (1629.7 and 117.77 g), moisture scavenger (1608.83 and 115.13 g), O 2 scavenger (1528.7 and 110.83 g), CO 2 scavenger (1483.0 and 105.07 g) and control samples (1353.9 and 87.63 g) respectively. It was found that AP treatments except O 2 and CO 2 scavengers significantly reduce the decrease in texture and firmness value. Fig. 5.10(a): Effect of active packaging on texture (shear force) of MP apple Fig. 5.10(b): Effect of active packaging on firmness (shear force) of MP apple Figs. 5.10 (c and d) present the observations regarding changes in texture (Table 5.19) and firmness (Table 5.20) in banana slices. In the present study the intial value for texture and firmness for banana was observed (520.27 and 35.93 g) which decreased during storage and it was found that at 15 th day the chitosan coated banana slices had highest texture and firmness value (300.63 and 28.23 g) of shear strength followed by samples treated with ethylene scavenger (270.17 and 25.37 g), moisture scavenger (254.47 and 24.83 g), O 2 scavenger (253.33 and 22.87 g), CO 2 scavenger (259.83 and 21.6 g) and control samples (215.77 and 17.5 g) respectively. It was found that AP treatments except O 2 and CO 2 scavengers significantly reduced the decrease in texture whereas, AP treatments significantly reduce the decrease in firmness value. 82

Fig. 5.10(c): Effect of active packaging on texture (shear force) of MP banana Fig. 5.10(d): Effect of active packaging on firmness (shear force) of MP banana Figs. 5.10 (e and f) depict the observations regarding changes in texture (Table 5.19) and firmness (Table 5.20) in orange fragments. In the present study the intial value for texture and firmness for orange was observed (1946.33 and 54.7 g) and it was found that at 15 th day the ethylene scavenging treated samples had highest texture and firmness value (1585.63 and 45.07 g) of shear strength followed by samples treated with moisture scavenger (1360.8 and 43.6 g), O 2 scavenger (1330.17 and 41.33 g), CO 2 scavenger (1177.03 and 27.63 g), chitosan coated registered (1075.53 and 25.73) values and control samples possessed lowest value (605.77 and 18.1 g) respectively. It was found that AP treatments significantly reduce the decrease in texture and firmness value in MP orange. Fig. 5.10(e): Effect of active packaging on texture (shear force) of MP orange Fig. 5.10(f): Effect of active packaging on firmness (shear force) of MP orange 83

Figs. 5.10 (g and h) express the observations regarding changes in texture (Table 5.21) and firmness (Table 5.22) in tomato slices. In the present study the intial value for texture and firmness for tomato was observed (2813.3 and 140.5 g) and it was found that at 15 th day the chitosan coated tomato slices exhibited texture and firmness value (2270.33 and 91.4 g) of shear strength followed by samples treated with ethylene scavenger (2243.2 and 90.5 g), moisture scavenger (2146.5 and 90.13 g), O 2 scavenger (1840.3 and 79.33 g), CO 2 scavenger (1563.93 and 73.2 g) and control samples recorded lowest value (1234.03 and 63.73 g) respectively. It was found that AP treatments significantly reduce the decrease in texture and AP treatments except CO 2 scavenger significantly reduce in firmness value in MP tomato. Fig. 5.10(g): Effect of active packaging on texture (shear force) of MP tomato Fig. 5.10(h): Effect of active packaging on firmness (shear force) of MP tomato Figs. 5.10 (i and j) represent the observations regarding changes in texture (Table 5.21) and firmness (Table 5.22) in florets of cauliflower. In the present study the intial value for texture and firmness for cauliflower was observed (5106.47 and 507.7 g) and it was found that at 15 th day the chitosan coated cauliflower florets had highest texture and firmness value (3461.43 and 336.97 g) of shear strength followed by samples treated with ethylene scavenger (3261.93 and 326.9 g), moisture scavenger (3141.37 and 324.07 g), O 2 scavenger (2172.03 and 254.07 g), CO 2 scavenger (2173.7 and 242.93 g) and control showed lowest value 1770.9 and 206.67 g respectively. AP treatments significantly reduce the decrease in texture and firmness value in MP cauliflower. 84