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Influence of zein and gelatin coatings on the postharvest quality and shelf life extension of mango (Mangifera indica L.)
- Neeta B. Gol, T.V. Ramana Rao
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Introduction. Mango is the most economically important and nutritionally rich tropical fruit; it has high commercial value but a highly perishable nature; its sensitivity to postharvest diseases and physical injury limits its successful marketing. Postharvest losses in fruits are a serious problem because of rapid deterioration during handling, transport and storage. Edible films and coatings can be potentially used as an elective preservation technique to extend the shelf life of fruits. Materials and methods. The influence of zein and gelatin coatings on the physicochemical characteristics, softening and antioxidative enzyme activities of mango fruits stored at (32 ± 1) °C were evaluated at regular intervals of their storage period and compared with mango without coatings (control). Results and discussion. Zein and gelatin coatings seemed to have a beneficial impact on delaying the changes in weight loss, soluble solids, titratable acidity, pH, sugar content and total carotenoids. Zein and gelatin coatings resulted in the highest retention of ascorbic acid and phenolic content as compared with that of control. Zein and gelatin coatings delayed the ripening of mango fruit by suppressing the activity of softening enzymes such as polygalacturonase, pectin methyl esterase, cellulase and β-galactosidase. Zein 5% and gelatin 10% coatings maintained the highest induction of defense-related peroxidase enzymes, followed by gelatin 5% and zein 10% coatings. Conclusion. The application of zein 5% and gelatin 10% coatings could be used in delaying the ripening, maintaining the quality attributes and extending the shelf life of mango fruit during storage.
Physiochemical changes in sunberry (Physalis minima L.) fruit during growth and ripening
- Prakash R. Patel, Neeta B. Gol, Tadapaneni V. Ramana Rao
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Introduction. Physalis minima is a widespread, quick-growing and high fruit-yielding annual herb belonging to the family Solanaceae. However, like many other underutilized fruit-bearing plants, P. minima is poorly studied and its nutritional potential is unknown. Since the edible sunberry is said to be a rich source of vitamin C, we studied the physiochemical changes during its fruit growth and ripening. Materials and methods. The changes in the physiochemical properties, such as pH, total soluble solids, titrable acidity, chlorophylls, carotenoids, carbohydrates (reducing sugars, non-reducing sugars, total sugars and starch), free amino acids, total proteins, total phenols, ascorbic acid, ethylene, and respiration and the activities of hydrolytic enzymes (amylase and invertase), antioxidant enzymes (catalase and peroxidase), and cell wall-degrading enzymes (cellulase, polygalacturonase and pectinmethylesterase), were analyzed in the fruit of sunberry at five sequential stages, viz., the young, premature, mature, preripe and ripe stages. Results and discussion. A gradual increase in the pH and total soluble solids occurred throughout the growth and ripening of sunberry fruit, while its titrable acidity increased up to the preripe stage and thereafter declined. A decreasing trend in the chlorophylls occurred simultaneously with an increase in the quantity of carotenoids. As the sunberry fruit proceeded towards ripening, the amount of its total starch decreased, with a concomitant sharp increase in the quantity of its reducing sugars, non-reducing sugars and total sugars. An increase in the quantity of free amino acids, proteins and phenols also occurred during the growth and ripening of the fruit, and the quantity of ascorbic acid increased at the mature stage. Moreover, sunberry fruit also exhibits a climacteric behavior with increased ethylene production and rate of respiration. The specific activity of amylase increased throughout the growth period of sunberry, but that of invertase decreased after maturity until ripening. The catalase and peroxidase enzymes showed higher activity, indicating better radical scavenger properties, while cellulase, polygalacturonase and pectinmethylesterase tended to remain at lower levels. Conclusion. The fruit of P. minima are nutritive and a rich source of sugars, starch, free amino acids, proteins, total phenols and ascorbic acid. They are metabolically active, showing a high specific activity of hydrolyzing and antioxidant enzymes, while the activity of cell wall-degrading enzymes is relatively low, indicating a better postharvest storage life.