Abstract: Young tea leaves from four different cultivars (Yinghong 9, Fuding Dabai, Jinguanyin and Chuyeqi) at the same growth phase were subjected to suspended fermentation. By doing so, we aimed to evaluate the effect of different tea cultivars varying in the activities of polyphenol oxidase (PPO) and peroxidase (POD) and their ratio as well as catechin contents on theaflavin formation during the fermentation process. The results showed that the value of PPO/POD ratio was the highest in Fuding Dabai, followed by Yinghong 9 and Jinguanyin. Total simple catechins (TSC) and total ester-type catechins (TETC) were the highest in Yinghong 9, followed by Fuding Dabai and Jinguanyin, and Chuyeqi contained the lowest levels of TSC and TETC. All the catechins except (-)-gallocatechin gallate (GCG) and catechin gallate (CG) showed a rapid decline in the early stage of fermentation, and remained stable in the later stage. The catechins were dramatically consumed during the first 30 min of fermentation. The formation of theaflavins firstly increased, reaching a peak at 15 and 30 min and then decreased. Each theaflavin in fermented tea leaves from the various was found to differ in their peak time and height. In general, the amount of theaflavins produced during the fermentation of Yinghong 9, showing the second lowest PPO/POD ratio and highest catechin content was significantly higher compare with the other cultivars. Theaflavins were formed at the highest rate during the fermentation of Fuding Dabai and Jinguanyin, with the highest PPO activity. On the other hand, higher POD activity and lower catechin content resulted in the formation of less theaflavins. The lowest amount of theaflavins was formed during the fermentation of Chuyeqi, having the lowest PPO/POD ratio and lowest catechin content. Therefore, higher theaflavin formation was related to higher PPO/POD ratio, catechins content and TETC/TSC ratio.

Key words: polyphenol oxidase, peroxidase, catechins, tea cultivar, theaflavins