Institute of Chemistry and Environment Engineering, Hanshan Normal University, Chaozhou, P. R. China.
PLoS One. 2022 Oct 13;17(10):e0276044. doi: 10.1371/journal.pone.0276044. eCollection 2022.
Fenghuang Dancong, Tieguanyin, and Dahongpao teas are belonged to semi-fermented oolong teas and are famous for their unique aroma. However, reports regarding the systematic comparison, differentiation, and classification of the volatile components of these three types of oolong teas are lacking. In this study, we aimed to establish a method for distinguishing these three types of oolong teas. The volatile components in a total of 21 tea samples of these three types of oolong teas were extracted, determined, and identified by headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS). In addition, chemometric methods such as hierarchical cluster analysis (HCA), principal component analysis (PCA), and orthogonal partial least squares discriminant analysis (OPLS-DA) were used for distinguishing and classifying the three types of oolong teas on the basis of the similarities and differences in the volatile components. The results showed that 125 volatile components were extracted and identified from the three types of oolong teas, among which 53 volatile components overlapped among the samples. The results of HCA indicated that the samples of each of the three types of oolong teas could be placed in one category when the t value was 220. The results of PCA and OPLS-DA showed that the volatile components such as dehydrolinalool, linalool oxide II, linalool, α-farnesene, linalool oxide I, β-ocimene, nerolidol, cis-3-butyric acid folate, myrcene, and (Z)-hexanoic acid-3-hexenyl ester are the characteristic components, which can be used to distinguish the three types of oolong teas. We developed a simple, fast, and efficient method for distinguishing three types of oolong teas and provided a feasible technique for the identification of oolong tea types.
凤凰单枞、铁观音和大红袍茶都属于半发酵乌龙茶，以其独特的香气而闻名。然而，关于这三种乌龙茶挥发性成分的系统比较、区分和分类的报道还很少。本研究旨在建立一种区分这三种乌龙茶的方法。采用顶空固相微萃取（HS-SPME）结合气相色谱-质谱（GC-MS）提取、测定和鉴定这三种乌龙茶共 21 个茶样中的挥发性成分。此外，还采用层次聚类分析（HCA）、主成分分析（PCA）和正交偏最小二乘判别分析（OPLS-DA）等化学计量学方法，基于挥发性成分的相似性和差异性，对三种乌龙茶进行区分和分类。结果表明，从三种乌龙茶中提取并鉴定出 125 种挥发性成分，其中 53 种挥发性成分在样品中重叠。HCA 的结果表明，当 t 值为 220 时，三种乌龙茶的样品可以归为一类。PCA 和 OPLS-DA 的结果表明，脱水芳樟醇、氧化芳樟醇 II、芳樟醇、α-法呢烯、氧化芳樟醇 I、β-罗勒烯、橙花醇、顺-3-丁酸叶酸、月桂烯和(Z)-己酸-3-己烯酯等挥发性成分是特征成分，可以用来区分三种乌龙茶。我们开发了一种简单、快速、高效的区分三种乌龙茶的方法，为乌龙茶类型的鉴定提供了一种可行的技术。
