When ultrasound was applied for 50, 100, and 150 s without antioxidants, the residual activity of PPO was 94.53%, 75.74%, and 43.06%, respectively.
Denaturation of protein is mainly responsible for the ultrasonic inactivation mechanism of enzymes, either by free radicals in sonolysis of water molecules or from the shear force resulting from the formation or collapse of cavitating bubbles .