Effect of different inhibitors on anti-browning of Pinklady apple

The inhibitive effects of oxalic acid,EDTA-Na2,citric acid and their compounds to the polyphenoloxidase(PPO) of Pinklady apple were studied and their anti-browning effects were explored.The results showed that the inhibitive effect of a single inhibitor to PPO was in the order of 0.25 μmol/L oxalic acid0.50 μmol/L EDTA-Na20.20 μmol/L citric acid.The inhibited rate was 94.30%,83.01% and 81.31% respectively.The inhibitive effects of all three inhibitors were largely depended on their concentrations and showed irreversibility.0.25 μmol/L oxalic acid was better in restraining browning in fresh apple juice,with a 87.39% of inhibited rate,while the inhibition abilities of 0.50 μmol/L citric acid was weaker,only with a 45.15% of inhibited rate.0.50 μmol/L EDTA-Na2 could not inhibit browning.The inhibited browning rate was only 71.04% when added 0.25 μmol/L oxalic acid into apple juice and stored ninety days.The mixed solution of 0.30 μmol/L oxalic acid,0.50 μmol/L EDTA-Na2 and 0.50 μmol/L citric acid could greatly inhibit browning,and the inhibited rate in the fresh and the stored apple juice was 91.21% and 89.47% respectively.