苹果梨中多酚氧化酶的性质及多酚成分定性

摘要

With apple pears of polyphenol oxidase(PPO) as the research object , the characterization of polyphenol oxidase and composition of polyphenols were studied. Using spectrophotometric method to determine the enzyme activity,the qualitative of phenolic in apple pears was determined by high performance liquid chro-matography(HPLC). PPO enzyme activity reached the top when pH was 7.8,and when pH was7.4 enzyme activ-ity declined not obviously, when the concentration of substrate was more than 3 mmol/L the activity of PPO was decreased with the concentration of substrate increased, enzyme activity reached the top when the substrate was epicatechin . Catechol, chlorogenic acid, epicatechin and meletin could be detected in the flesh of apple pear by polyphenols by high performance liquid chromatography(HPLC). The results showed that the optimum pH of PPO was 7.8, when pH was 7.4, the stability of PPO was the strongest, PPO had the best affinity with epicate-chol, among the total, the contents of chlorogenic acid was highest, the catechol and meletin was second.%以苹果梨中的多酚氧化酶（PPO）为研究对象，对其酶的性质及多酚成分进行研究。采用分光光度法测定酶活，利用高效液相色谱法定性苹果梨果肉中的酚类物质。PPO在pH值为7.8时酶活波峰最大，在7.4时酶活下降趋势最不明显；当底物浓度大于3 mmol/L时，随着浓度的增加，PPO活性反而下降，底物为表儿茶酚时酶活最强；苹果梨果肉中可检测到的酚类物质包括儿茶酚、绿原酸、表儿茶素和槲皮素。结果表明：PPO的最适pH值为7.8，PPO在pH为7.4时最稳定；表儿茶酚和PPO的亲和力最高；苹果梨中的酚类物质绿原酸含量最多，其次含量较高的是儿茶素和槲皮素。