影响荔枝果肉酶促褐变主要酶性质的比较研究

摘要

This thesis did a comparative study on chracterization of Polyphenolxidase and Peroxidaseduring the enzymatic browning of litchi pulp. The activity of POD is far greater than the activity of PPO,however, the thermal stability of PPO was higher than that of PPO, therefore the polyphenol oxidase was adopted as the indicator of inactivating enzyme. And the activity of peroxidase can be completely inhibited by the glutathione , but the activity of polyphenol oxidase e can be inhibited transiently by the glutathione.The polyphenol oxidase and peroxidase of the pH stability was the same, at the pH less than 5 that under acidic conditions, two kinds of enzyme activity and stability dropped, thereby inhibiting the enzymatic browning.%比较研究了在荔枝果肉酶促褐变过程中，多酚氧化酶和过氧化物两种酶的性质。在荔枝果肉中过氧化物酶的活性远远大于多酚氧化酶的活性。但是PPO的热稳定性高于POD的热稳定性，应以多酚氧化酶作为灭酶的指标；并且有化学抑制剂可以完全抑制过氧化物酶活性，但对多酚氧化酶却具有抑制暂时性。pH对多酚氧化酶和过氧化物酶的稳定性影响基本一致，在pH小于5的酸性条件下活性和稳定性下降，因而在酸性条件下，可有效抑制酶促褐变。