Changes in physicochemical properties and enzymes associated with ripening of snake tomato (Trichosanthes Cucumerina L.) fruit

Abstract

Changes accompanied ripening of fruits as well as reduction in quality and/or nutritional qualities of fruits are caused by enzymes released during growth and development of the fruits. This study was intended at investigating physicochemical changes and enzymes associated with ripening of three varieties of snake tomato fruit. Firmness, ascorbic acid, moisture, non-reducing sugar, total chlorophyll and colour parameter L* value were decreased as ripening progressed while total soluble solid, carotenoids, total sugar, reducing sugar, and colour parameter a* and b* values increased as the fruits ripened. Activities of polyphenol oxidase, pectin methylesterase and α-mannosidase were maxima at half ripe stage in coat and pulp while cellulase and polygalacturonase activities were maxima at fully ripe stage in light green, light green with white stripe and dark green with white stripe varieties. Steady increased activities of pectin methylesterase, polygalacturonase and cellulase during fruit ripening correlate with decrease in firmness of the three snake tomato varieties. This establishes the roles the enzymes play on the loss of firmness (softening) of three varieties of snake tomato fruits in the course of ripening.