关键词: 工夫红茶；品质成分；香气；主成分分析；综合评价

Abstract: This study aimed to explore the characteristics of the contents of the major quality components in Congou black tea and to develop a comprehensive evaluation method for the taste quality of tea infusion. A total of 17 black teas from the main tea-producing regions of China were measured for quality indicators including polyphenols, amino acids, tea pigments and volatile components and comprehensive evaluation of their quality was investigated by principal component analysis (PCA), cluster analysis (CA) and partial least squares discriminant analysis (PLS-DA). The results showed that the composition and contents of quality components varied significantly among the different black teas. Polyphenols and their oxidation products were the major quality components. The ratio of the sum of theaflavins and thearubigins to theabrownins was 1.05–1.12, which constituted the material basis of the fresh and mellow taste and the red bright color of tea infusion. Yinghong, Haihong, Xinyanghong, Yihong, Yuehong, Qianhong and Qihong had soluble sugar contents higher than 4%, which was an important material basis of the sweet and mellow taste of tea infusion. The flavonoid content in large-leafed black tea (Dianhong, Yinghong and Haihong) was higher than 2.7%. Alcohols and aldehydes were the principal aroma compounds, especially terpene alcohols, responsible for the sweet and floral aroma and more abundant than other aroma compounds. PCA was used to establish a taste quality evaluation model. The model prediction was consistent with the sensory evaluation, indicating a significant correlation between them (P < 0.01) with a correlation coefficient of 0.735. The contents of theaflavins and tea polyphenols were important indicators of Congou black tea quality. Cluster?analysis?revealed?that?Minhong belonged to one class, Dianhong, Yinghong and Haihong shared?similar?quality?characteristics,?while?other middle- and small-leafed black teas belonged to a third class. PLS-DA showed a clear discrimination between the large-leafed black tea and the middle- and small-leafed black teas with eight differential quality indicators. Notably, inalol, geraniol and hexanal could be used to discriminate between the two classes of black tea. The results of this study enrich the basic theory of Congou black tea flavor quality and provide new ideas and methods for the scientific evaluation of black tea quality.

Key words: Congou black tea; quality components; aroma; principal component analysis; comprehensive evaluation