六堡茶渥堆过程中添加外源酶对主要物质转化规律的影响

Effects on changes of main substances added exogenous enzymes during pile-fermentation of Liu Pao tea

通过在六堡茶的渥堆过程中添加纤维素酶、果胶酶、木瓜蛋白酶和过氧化物酶,监测六堡茶渥堆原料中水浸出物、茶多酚、氨基酸、可溶性总糖及咖啡碱含量的变化,研究外源酶对六堡茶主要物质转化规律的影响。结果表明随着渥堆时间的增加,水浸出率及茶多酚、游离氨基酸和可溶性总糖的含量虽然有些小的波动,但总体上呈现逐渐降低的趋势,咖啡碱含量略微增加。在渥堆的前15 d,纤维素酶、果胶酶和木瓜蛋白酶可以提高水浸出率,特别是纤维素酶和果胶酶在渥堆10 d时使水浸出率分别提高5.32%和5.95%;渥堆时间超过15 d后,添加外源酶的茶叶水浸出率反而降低;纤维素酶和果胶酶在渥堆前期能够促进茶多酚的转化,在渥堆10 d时,茶多酚的降解率提高了4.00%,而过氧化物酶在渥堆(20~25)d内可以促进茶多酚的转化;木瓜蛋白酶能够显著增加游离氨基酸含量;果胶酶和纤维素酶提高可溶性总糖含量的效果明显,在渥堆(5~15)d时间段内,可溶性总糖含量可提高13%~22%;在渥堆中后期果胶酶可以提高咖啡碱含量,渥堆20 d时,咖啡碱含量提高7.36%,而过氧化物酶在一定程度上可以降低咖啡碱含量。通过研究,探明了不同的外源酶对茶叶中主要物质转化规律的影响,为改善六堡茶的品质和缩短渥堆时间提供了理论依据。

The paper studied on the effects of exogenous enzymes on changes of main substances by monitoring changes of water extract and the contents of tea polyphenol, free amino acid, soluble sugar and caffeine after adding cellulase, pectinase, papain and peroxidase during pile-fermentation of Liu Pao tea. The result showed that with increasing time of pile-fermentation, the water extract and the contents of tea polyphenol, free amino acid and soluble sugar had a little fluctuation, but all were decreased on the whole, the contents of caffeine had a little increase. During the period of （0-15） days of pile-fermentation, cellulase, pectinase and papain could increase the water extracts, especially cellulase and pectinase could respectively increase water extract by 5.32% and 5.95% at time of 10 day, but the time of pile- fermentation were more than 15 days, these experimental samples added exogenous enzymes could reduce the water extracts. Cellulase and pectinase could promote conversion of tea polyphenol during pre-pile-fermentation, the degradation rate of tea polyphenol increased by about 4.0% at the time of 10 day, peroxidase could promote the conversion of tea polyphenol during the period of （20N25） days. Papain could increase obviously the content of free amino acid. Celtulase and pectinase could increase apparently the contents of soluble sugar of tea, which could increase by 13%-22% during the period of （5-15） days. In the mid-to late- pile-fermentation, pectinase could increase the contents of caffeine, which increased by 7.36%, but peroxidase could decrease the content of caffeine to some extent. The paper proved the effects of four kinds of exogenous enzymes on the changes of main substances and provided scientific basis for Liu Pao tea to improve quality and reduce time of pile-fermentation.