The influences of different inhibitors on polyphenoloxidase activity in granny smith apple

Polyphenol oxidase activities of Granny Smith apple were determined at 420nm with pyrocatechol as substrate by spectrophotometry.In this paper,the effect of anti-browning inhibitors-NaHSO3,ascorbic acid and citric acid,which could inhibit Granny Smith PPO activities,were particularly studied.Through orthogonal test,the optimum mixed inhibitor of Polyphenol oxidase was obtained.The experiment results showed that adding 50mg/kgNaHSO3 or 125mg/kg ascorbic acid or 600mg/kg citric acid in the reaction systems could inhibit PPO activities effectively in Granny Smith apple.Of the three inhibitors,NaHSO3 had the most effect on PPO,the inhibition rate was up to 78.58%.The best mixed inhibitors of Polyphenol oxidase was adding 25mg/kgNaHSO3 and 125mg/kg ascorbic acid and 600mg/kg citric acid in the reaction systems.The effect of mixed inhibitors of Polyphenol oxidase was evident,and the inhibition rate of PPO activity could reach to 90.09%.