Physicochemical qualities and antioxidant properties of juice extracted from ripe and overripe wax apple as affected by pasteurization and sonication

摘要

The present study investigated the effect of sonication alone and sonication withsubsequent pasteurization on physicochemical and antioxidant properties of juiceextracted from the ripe or overripe wax apple. Samples were sonicated for varyingtimes (0-10min) at a fixed frequency (28 kHz) and temperature (20°C) and then,pasteurized at 90°C for 2 min. Irrespective of the maturity, sonication improved thecolor characteristics (lightness, chroma, and hue) of wax apple juices (p > .05). Otherquality parameters (titratable acidity, total soluble solids, cloud value and electricalconductivity) exhibited similar changes for all the juice samples tested. Sonicatedsamples retained higher antioxidant activity (5%-30%),especially in the ripe juice,whereas pasteurization significantly reduced (5%-20%)the antioxidant activity, aswell as the total phenolic content. Moreover, sonication significantly reduced theenzyme activities, including polyphenol oxidase, polygalacturonase, pectin methylesterase,and peroxidase by 2%-10%when compared with pasteurization. Overall,sonication, either individually or in conjunction with pasteurization or thermal processing,was beneficial for maintaining the quality by inactivating enzymes, and retainingnutrients, whereas pasteurization degraded these juices.