Effect of Heat Processing and Ultrasonication Treatment on Custard Apple Peroxidase Activity and Vitamin C

Abstract

Abstract: Peroxidase isolated from custard apple (Annona squamosa L.) being a heat stable enzyme can be inactivated by heat processing and ultrasonication treatment as well. Heat processing took up to 22 min at 91 °C for complete inactivation of peroxidase. The ultrasonication treatment was performed at 40, 55, 70, 85 and 100 W ultrasonic power and was found to achieve complete inactivation at 85 W as well as at 100 W power within 5 min. The heat inactivation followed first-order reaction kinetics and the activation energy (Ea) calculated from Arrhenius plot was found to be 7.03 × 104 J/mol, which was near the reported range for peroxidases. Heat processing caused 52.7 % loss of vitamin C while achieving complete inactivation of peroxidase at 91 °C for 22 min, whereas ultrasonication caused 21.6 % vitamin C loss at 85 W power within 5 min. Ultrasonication was thus found to be efficient in retaining vitamin C while achieving complete enzyme inactivation.