野化白云黄茶闷黄过程中的品质成分变化及其菌种分离鉴定

为了掌握野化白云茶树鲜叶加工成黄茶加工过程的影响因素，该研究对比分析了野化白云茶加工的黄茶、烘青绿茶、半烘半炒绿茶的主要品质成分；分析了野化白云茶鲜叶加工黄茶过程中的依工艺阶段取8个茶样（茶青、杀青叶、揉捻叶、再炒叶（除水叶）、闷黄24 h、闷黄48 h、闷黄72 h、毛茶）可培养菌种的变化。野化白云茶与烘青绿茶、半烘半炒绿茶比较，除氨基酸、咖啡碱含量略有下降外，水浸出物含量分别高出4.80%、7.11%，可溶性糖含量分别高出0.41%、0.36%，茶多酚含量、儿茶素总含量呈下降趋势，酯型儿茶素总量下降21.62 mg/g、19.08 mg/g，EGCG下降9.99 mg/g、6.98 mg/g，GCG下降14.23 mg/g、13.80 mg/g，以上成分变化均差异显著（p<0.05）；非酯型儿茶素组分中除C减小2.49 mg/g、1.75 mg/g（p<0.05）外，其余非酯型儿茶素组分和总含量变化差异不显（p>0.05）；闷黄24 h，酵母菌数量明显，至72 h霉菌成优势菌种（3.5×105 CFU/g）；分离鉴出8株微生物，包括1株拟盘多毛孢属，4株青霉属，1株枝孢属及2株酵母菌属，其中Penicillium exsudans菌首次从茶叶加工中和茶叶中分离并鉴定。说明闷黄使茶叶水溶性物质、可溶性糖增加，茶多酚、酯型儿茶素下降，闷黄阶段有微生物繁殖并参与黄茶品质的形成。

Changes in Tea Quality Components in the Yellowing Process of Wild Baiyun Yellow Tea and the Isolation and Identification of Microbial Strains

In order to investigate the factors influencing the processing s of yellow tea from fresh leaves of wild Baiyun tea species, the main quality components of yellow tea, roasted green tea and half- baked and half-fried green tea processed from wild Baiyun tea were analyzed. The changes of culturable strains in the 8 tea samples (green tea, pan-fried green tea, rolling leaves, refried leaves (dehydrated leaves), leaves with 24 h smothering, leaves with 48 h smothering, leaves with 72 h smothering, and raw tea) withdrawn from the yellow tea processing of the fresh leaves of wild Baiyun tea were examined. The comparison of the wild Baiyun tea with the baked green tea, and the half-baked and half-fried green tea revealed that in addition to the slight decreases in amino acid and caffeine contents, the wild Baiyun tea had a higher water extract content (increased by 4.80% and 7.11%, respectively) , a higher soluble sugar content (increased by 0.41% and 0.36%, respectively), but lower tea polyphenol content and total catechin content (ester-type catechin content decreased by (21.62 mg/g and 19.08 mg/g, EGCG content decreased by 9.99 mg/g and 6.98 mg/g, and GCG content decreased by 14.23 mg/g and 13.80 mg/g, respectively). All these changes were significant (p<0.05). There were no significant changes in the contents of the non-ester catechins and the total content of non-ester catechins, except that C was reduced by 2.49 mg/g and 1.75 mg/g, respectively (p<0.05). After smothering for 24 hours, a significant number of yeast was detected, and fungi became dominant (3.5×105 CFU/g) after smothering for 72 hours. Eight microbial strains were isolated and identified, including 1 Pestalotiopsis strain, 4 Penicillium strains, 1 Cladosporum strain and 2 yeast strains, with Penicillium exsudans being isolated and identified for the first time from tea processing and tea leaves. The results indicated that smothering of tea increased the water-soluble and soluble sugar contents of tea, decreased the contents of tea polyphenols and ester-type catechins. Microbial reproduction occurred in the yellowing stage and participated in the formation of yellow tea quality.