抑制剂对鲜榨蜜梨汁多酚氧化酶活性的影响

Effects of Enzyme Inhibitors on PPO Activity in Fresh Pear Juice

多酚氧化酶(PPO)是酶促褐变的关键酶,以鲜榨蜜梨汁为原料,以邻苯二酚为底物,采用分光光度法测定多酚氧化酶活性,研究氯化钠、柠檬酸、L-半胱氨酸、抗坏血酸和异抗坏血酸5种不同抑制剂对鲜榨蜜梨汁中的多酚氧化酶活性的影响。结果表明,这5种酶抑制剂均能在一定程度上抑制鲜榨蜜梨汁PPO活性,随着其浓度的升高,抑制效应逐渐增强。氯化钠、柠檬酸、L-半胱氨酸、抗坏血酸、异抗坏血酸抑制鲜榨梨汁PPO活性的最佳浓度分别为0.6,0.5 mol/L和2.0,2.0,0.5 mmol/L。

Polyphenol oxidase enzyme （PPO） is a key enzyme of the enzymatic browning. Based on substrate of catechol, the characteristics of PPO and the effects of various inhibitors （sodium chloride, citric acid, L-cysteine, ascorbic acid and D-isoascorbate acid） on PPO activity in fresh pear juice are investigated by spectrophotometry method. The results of the single factor experiments show that the inhibitors selected can inhibit PPO activity evidently. As the concentration of inhibiters increasing, the inhibitory effects increase gradually. The optimum inhibitory concentrations of sodium chloride, citric acid, L-cysteine, ascorbic acid and D-isoascorbate acid are 0.6, 0.5 mol/L, 2.0, 2.0, 0.5 mmol/L, respectively.