Inactivation of Polyphenoloxidase and Peroxidase in Apple Cubes and in Apple Juice Subjected to High Intensity Power Ultrasound Processing

Abstract

This study has evaluated the inactivation of peroxidase (POD) and polyphenoloxidase (PPO) in apple cubes and in apple juice by ultrasonic treatment. Apple cubes and apple juice were subjected to ultrasonic processing by applying power densities ranging from 55 to 3300 W/L. Processing was carried out at temperatures ranging from 23C (ambient) to 60C and processing times ranging from 5 to 20 min, corresponding to the main operating conditions usually applied in ultrasonic treatment. Ultrasound application resulted in partial inactivation of both PPO and POD under specific operating conditions. An increase in enzyme activity was also observed for POD with increasing processing time and for PPO at higher temperatures (60C). Practical Applications Peroxidases and polyphenoloxidases are enzymes directly related to enzymatic browning in fruits. The inactivation (partial or complete) of these enzymes can provide a food product with lighter and more natural color. Ultrasound application was shown to increase the efficiency of several industrial processes and to positively affect the quality of food products. Ultrasound processing could be used as a simple method for enzyme inactivation.