黑茶发酵优势菌对茶多酚的生物转化研究

利用从茯砖茶中分离出的冠突散囊菌和从普洱茶中分离出的黑曲霉、根霉分别接种于以茶多酚作为唯一碳源的培养基中,进行单一菌株发酵,对发酵过程茶多酚类化合物的变化规律进行分析.结果表明,发酵期内,随着发酵时间延长,各发酵液的茶多酚总量显著降低,冠突散囊菌、黑曲霉、根霉发酵液中多酚分别降低38.9％、85.5％和92.1％;黄酮类总量在黑曲霉、根霉的作用下先下降后上升,冠突散囊菌则波动上升;各处理儿茶素总量均显著下降,其中酯型儿茶素含量直线下降,非酯型儿茶素和没食子酸的含量均先增加后减少.在黑曲霉、根霉作用下,茶黄素、茶红素含量显著减少,茶褐素含量增加.冠突散囊菌发酵液中茶黄素含量减少,茶红素含量增加,茶褐素含量基本不变.基于不同优势菌对茶多酚的转化在质和量上均有差异,有必要对其转化产物进行深入研究.

Biotransformation of tea polyphenols by fungi isolated from dark tea

In this study, Eurotium cristatum isolated from Fuzhuan tea and Aspergillus niger and Rhizopus isolated from pu-erh tea, were inoculated on the media with tea polyphenols as sole carbon source and fermented respectively. Tea polyphenols contents in different fermentation periods were determined. Results showed that the content of tea polyphenols significantly decreased with the fermentation time. The transformation rate of tea polyphenols in the fermentation broth of E. cristatum, A. niger, Rhizopus were 38.9%, 85.5%, 92.1%, respectively. The contents of flavonoids decreased first andthen increased by A. niger and Rhizopus, and increased in Eurotium cristatum fermentation broth irregularly. Levels ofepiglloctechingllte (EGCG), glloctechingllte (GCG), epictechingllte (ECG), ctechingllte (CG) significantly decreased bydegradation, while levels of glloctechin (GC), ctechin (C), epiglloctechin (EGC), epicatechin (EC) and gallic acid (GA)increased first and then decreased under the influence of microbes. Theaflavins, thearubigins decreased and theabrowninincreased by A. niger and Rhizopus. E. cristatum reduced the theaflavins and increased the content of thearubigins. It wasnecessary to study the biotransformation compounds deeply, because the biotransformations of tea polyphenols by differentfungi were different in both quantity and quality.