苹果果实酶促褐变底物及多酚氧化酶活性的研究

 以5个苹果品种为试材，研究了果实的褐变度，绿原酸、儿茶素和表儿茶素含量及多酚氧化酶(PPO)对不同底物的活性。结果表明，‘富士’果实褐变度最高，其次为‘新红星’，‘金冠’最低。3种酚类物质总量新红星和富士最高，金冠最低。儿茶素仅在‘乔纳金’和金冠果实中检测到少量。富士果实绿原酸含量显著高于表儿茶素，新红星和‘王林’表儿茶素含量显著高于绿原酸。以绿原酸为底物，PPO活性新红星最高，其次是富士和金冠，王林最低。以表儿茶素为底物，富士、乔纳金和王林PP0活性显著高于金冠和新红星。以儿茶素为底物，王林PPO活性最高，其次是富士，新红星最低。

Studies on Phenolic Composition and Polyphenol Oxidase Activity in Apple Fruits

The browning degree, content of chlorogenic acid, catechin, epicatechin and polyphenol oxidase (PPO) activity with different substrates in fruits of five apple cultivars were studied. The results indicated that the fruit with the highest browning degree was ' Fuji' apple followed by ' Starkrimson ' , ' Orinn' , ' Jonagold' and ' Golden Delicious' . The total content of these three phenolic compounds was the highest in Starkrimson and Fuji apple fruits, and lowest in Golden Delicious. Catechin was deteched only in Jonagold and Golden Delicious fruits. Chlorogenic acid content was distinctively higher than epicatechin in Fuji apple fruit, while epicatechin higher than chlorogenic acid in Starkrimson and Orinn fruit. Taking chlorogenic acid as substrate, the fruit with the highest PPO activity was Starkrimson followed by Fuji and Golden Delicious. Taking epicatechin as substrate, Fuji, Jonagold and Orinn fruits had higher PPO activity than Golden Delicious and Starkrimson. Taking catechin as substrate, PPO activity of Orin fruit was the highest followed by Fuji, and Starkrimson was the lowest.