Effect of Ohmic Heating on Polyphenol Oxidase Activity, Electrical and Physicochemical Properties of Fresh Tender Coconut Water

Abstract

Abstract Effect of ohmic heating on polyphenoloxidase (PPO) enzyme activity and the possible influence on the heating rate,electrical conductivity and physicochemical properties of tender coconut water was investigated in this study. Fresh tender coconut water was ohmically heated at voltage gradients of 15 and 20 V/cm, heating temperatures of 80, 90 and 100 °C and holding times of 0, 1.5 and 3 min. No significant changes were observed in pH, titrable acidity and color values of tender coconut water after ohmic heating. Increasing the voltage gradient from 15 to 20 V/cm and holding time from 0 to 3 min decreased the PPO activity significantly (p≤0.01) in tender coconut water. Tender coconut water heated at 80 °C at 20 V/cm for the holding time of 3 min showed the minimum residual PPO activity of 30.55±0.92 % and pink discoloration was retarded up to 7 days when stored at room temperature.