不同工艺制法对茶叶风味品质化学轮廓的影响

Effects of Different Processing Methods on Chemical Profiles of Tea in Relation to Flavor Quality

为探明不同工艺制法对茶叶风味品质化学轮廓的影响,本研究对福建4种茶类（绿茶、白茶、红茶和乌龙茶）及其鲜叶原料中的主要滋味和香气品质成分进行了检测分析和可视化模式识别。结果表明,基于茶叶主要滋味品质成分的主成分分析（PCA）可将全部供试茶样划分成3种类群：Ⅰ型：绿茶、白茶和一芽二、三叶鲜叶样;Ⅱ型：乌龙茶和中、小开面2~4叶鲜叶样;Ⅲ型：红茶。采用偏最小二乘增强判别分析（PLS-EDA）可进一步放大不同类群茶样的组间差异,乌龙茶及其鲜叶原料有较高含量的水溶性碳水化合物（WSCs）,而红茶中多酚类（TPs）和表没食子基儿茶素没食子酸酯（EGCG）含量相对较低;（茶多酚×游离氨基酸）含量二维散点视图可作为茶叶分类识别的一种重要判别工具。4种茶类以乌龙茶的香型种类最为丰富,绿茶与鲜叶原料的香气组成化学模式较为接近,白茶与红茶香气组成在种类和数量上存在一定的相似特征。2,6-二叔丁基对甲苯酚、苯乙腈、4-乙基苯甲酸-2-苯基乙酯类似物、反式-橙花叔醇、α-法呢烯、吲哚等可视为乌龙茶有别于其他3种茶类（绿茶、白茶和红茶）的主要特征香气成分。本研究结果为茶叶化学分类及其工艺品质的目标控制提供了参考依据。

To investigate the effects of processing methods on chemical profiles of tea in relation to flavor quality,the main taste components and aroma constituents in four different tea varieties（ green teas,white teas,black teas and oolong teas） and their source materials were determined and visualized by pattern recognition. The results showed that all tea samples could be differentiated into three groups with principal component analysis（ PCA）,i. e. Type Ⅰ： green teas,white teas and samples obtained from two or three leaves and a bud. Type Ⅱ： oolong teas and samples obtained from two to four leaves and a banjhi bud,and type Ⅲ： black teas. The differentiation of these three tea groups would be amplified with partial least-squares enhanced discriminant analysis（ PLS-EDA）. Higher contents of water soluble carbonhydrates would be found in oolong teas and their source materials, and the contents of polyphenols and（-）- epigallocatechin- 3- gallate（ EGCG） in black teas were relatively lower. Moreover,the two-dimensional scatter plot with the contents of tea polyphenols and free amino acids in tea samples could be considered as an important tool to discriminate tea categories. The aromas patterns of oolong teas were of the most different characters among four tea varieties,and the chemical pattern of green teas is similar to those of source materials; whereas some common characters with the amounts and constitutes of aromatic compounds would be revealed between white teas and black teas. In comparison with the other three tea varieties（ green teas,white teas and black teas）,butylated hydroxytoluene,benzyl nitrile,analogue of oxalic acid,di（ 2- phenylethyl） ester,trans-nerolidol,α- farnesene,indole,etc. were the characteristic aromas with great abundance in Oolong teas. The way based on pattern recognition of chemical constituents would provide a reference for classification and quality control of the afore-mentioned four kinds of teas.