Abstract:Based on the phenomenon that the passivation rate of ultrasonic wave on polyphenol oxidase and peroxidase in mango juice was significantly lower than that on mango crude enzyme solution, the possible factors affecting the passivation effect of ultrasonic wave were discussed by adjusting the content of food components and medium viscosity in the crude enzyme solution. The treatment conditions were 45 ℃, 799.31 W/cm2 and 15 min. It was found that the passivation rates of PPO and POD by ultrasound in crude enzyme solution with a sugar content of 5.0-20 Brix were decreased by 20.67%-29.36% and 40.34%-46.22% (P<0.05) respectively, compared with the original crude enzyme solution with a sugar content of 4.4 Brix. Similarly, the passivation rates of PPO and POD by ultrasound in crude enzyme solution with an additional amount of 0.5%-2.5% were decreased by 24.55%-30.9% and 42.36%-47.19% (P<0.05), respectively, compared with the original crude enzyme solution. The viscosity of the crude enzyme solution was adjusted by adding different thickeners, it was found that the passivation rates of PPO and POD by ultrasound in crude enzyme solution with the viscosity of 17.6-27.1 mPa·s were decreased by 27% and 30% (P<0.05), respectively, compared with the unadjusted group with viscosity of 15.2 mPa·s, but the ultrasonic inactivation effect among different thickeners was similar (P>0.05). The pH of the crude enzyme solution was adjusted by adding citric acid, it was found that the passivation rates of PPO and POD by ultrasound in crude enzyme solution with the pH of 4 and 5 were decreased by 22.73%-27.19% and 34.58%-41.32% (P<0.05), respectively, compared with the unadjusted group with pH of 5.2. The results indicated that food components, pH and medium viscosity could affect the enzymes inactivation ratio of ultrasound.