College of Longrun Pu-erh Tea, Yunnan Agricultural University, Kunming, Yunnan 650201, China.
State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei, 230036 Anhui China.
J Agric Food Chem. 2020 Apr 29;68(17):4946-4954. doi: 10.1021/acs.jafc.0c00513. Epub 2020 Apr 17.
Tannase (E.C. 3.1.1.20) is hypothesized to be involved in the metabolism of gallates and gallic acid (GA) in pu-erh tea fermentation. In this work, we measured tannase in fermented tea leaves and confirmed the production of fungal tannase during pu-erh tea fermentation. A decrease in catechin and theaflavin gallates and a significant increase in GA content and the relative peak areas of ethyl gallate, procyanidin A2, procyanidin B2, procyanidin B3, catechin-catechin-catechin, epiafzelechin, and epicatechin-epiafzelechin [variable importance in the projection (VIP) > 1.0, < 0.05, and fold change (FC) > 1.5] were observed using high performance liquid chromatography (HPLC) and metabolomics analysis of tea leaves fermented or hydrolyzed by tannase. assays showed that hydrolysis by tannase or polymerization of catechins increased the antioxidant activity of tea leaves. In summary, we identified a metabolic pathway for gallates and their derivatives in tea leaves hydrolyzed by tannase as well as associated changes in gallate and GA concentrations caused by fungal tannase during pu-erh tea fermentation.
单宁酶（E.C. 3.1.1.20）被认为参与了普洱茶发酵过程中没食子酸酯和没食子酸（GA）的代谢。在这项工作中，我们测量了发酵茶叶中的单宁酶，并证实了在普洱茶发酵过程中真菌单宁酶的产生。儿茶素和茶黄素没食子酸酯的含量下降，GA 含量和没食子酸乙酯、原花青素 A2、原花青素 B2、原花青素 B3、儿茶素-儿茶素-儿茶素、表儿茶素和表儿茶素-表儿茶素[变量重要性投影（VIP）>1.0，<0.05，倍数变化（FC）>1.5]的相对峰面积显著增加，这是通过高效液相色谱（HPLC）和代谢组学分析发酵或单宁酶水解的茶叶得到的。测定表明，单宁酶水解或儿茶素聚合增加了茶叶的抗氧化活性。综上所述，我们鉴定了单宁酶水解茶叶中没食子酸酯及其衍生物的代谢途径，以及在普洱茶发酵过程中真菌单宁酶引起的没食子酸酯和 GA 浓度的相关变化。
