Published online by Cambridge University Press: 24 January 2011
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 ispoorly studied and its nutritional potential is unknown. Since the edible sunberry is saidto be a rich source of vitamin C, we studied the physiochemical changes during its fruitgrowth and ripening. Materials and methods. The changes in the physiochemicalproperties, such as pH, total soluble solids, titrable acidity, chlorophylls, carotenoids,carbohydrates (reducing sugars, non-reducing sugars, total sugars and starch), free aminoacids, total proteins, total phenols, ascorbic acid, ethylene, and respiration and theactivities of hydrolytic enzymes (amylase and invertase), antioxidant enzymes (catalaseand peroxidase), and cell wall-degrading enzymes (cellulase, polygalacturonase andpectinmethylesterase), 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 solublesolids occurred throughout the growth and ripening of sunberry fruit, while its titrableacidity increased up to the preripe stage and thereafter declined. A decreasing trend inthe chlorophylls occurred simultaneously with an increase in the quantity of carotenoids.As the sunberry fruit proceeded towards ripening, the amount of its total starchdecreased, 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 thequantity of ascorbic acid increased at the mature stage. Moreover, sunberry fruit alsoexhibits a climacteric behavior with increased ethylene production and rate ofrespiration. The specific activity of amylase increased throughout the growth period ofsunberry, but that of invertase decreased after maturity until ripening. The catalase andperoxidase enzymes showed higher activity, indicating better radical scavenger properties,while cellulase, polygalacturonase and pectinmethylesterase tended to remain at lowerlevels. Conclusion. The fruit of P. minima are nutritive anda rich source of sugars, starch, free amino acids, proteins, total phenols and ascorbicacid. They are metabolically active, showing a high specific activity of hydrolyzing andantioxidant enzymes, while the activity of cell wall-degrading enzymes is relatively low,indicating a better postharvest storage life.