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.