Kinetics of inactivation of peroxidase and polyphenol oxidase in tender coconut water by dielectric barrier discharge plasma

Abstract

The spoilage enzymes in tender coconut water were inactivated by atmospheric cold plasma technology. The kinetics of peroxidase (POD) and polyphenol oxidase (PPO) inactivation was studied at voltage levels varying between 18 and 28 kV dielectric barrier discharge plasma treatments (DBD) at atmospheric air. The time of treatment and applied voltage were significant factors for inactivation of the enzymes. POD was more resistant than PPO. The experimentally observed data were fitted to establish different kinetics models and model parameters were evaluated. The sigmoidal logistic was the best fitting model to explain the kinetics of browning enzymes inactivation based on high RMSE values. The time required for half maximal activity values for POD was 0.84, 1.67 and 2.53 min at 18 kV, 23 kV and 28 kV, respectively which was higher than PPO with half maximal activity values of 0.67, 1.18 and 1.35 min, respectively. This indicates that POD is more resistant to cold plasma than PPO and its inactivation in tender coconut water by cold plasma can be considered as a crucial quality parameter. DBD generated cold plasma can therefore be used to process fruits and vegetables juices wherein enzymes activity is one of the quality deterioration parameters.