基于代谢组学的不同年份晒青红茶化学成分分析

为探究红茶在贮藏过程中化学成分的变化规律，以贮藏时间为0、1、3 a和4 a的晒青红茶为代表样品，采用基于超高效液相色谱-四极杆轨道阱质谱的代谢组学方法对其研究。结果表明，在不同年份晒青红茶中共鉴定出82 种化合物，包括儿茶素类6 种、二聚儿茶素类9 种、氨基酸类5 种、生物碱类8 种、酚酸类8 种、有机酸类3 种、香气糖苷类2 种、N-乙基-2-吡咯烷酮取代的儿茶素（N-ethyl-2-pyrrolidinone-substituted flavan-3-ols，EPSF）类6 种、黄酮糖苷类20 种、脂类10 种和其他化合物5 种。偏最小二乘法判别分析和热图分析结果表明，不同年份的晒青红茶化学成分具有较大差异，其中66 种化合物组间差异显著（P＜0.05），儿茶素类、二聚儿茶素类、氨基酸类和大部分黄酮醇-O-糖苷类化合物均在晒青红茶贮藏后含量降低；咖啡碱、黄酮-C-糖苷类和6 种EPSF类化合物在贮藏后含量升高；其中EPSF类化合物与贮藏时间的Pearson相关系数达0.802～0.986，表明EPSF类化合物在贮藏过程中呈线性增加趋势。本研究可为不同年份晒青红茶化学物质基础的阐明和科学贮藏提供理论依据。

Chemical Composition Profiling of Sun-Dried Black Tea of Different Ages Based on Metabolomics Approach

In order to investigate the changes in the chemical composition of black tea during storage, we analyzed sun-dried black tea stored for 0, 1, 3 and 4 years by metabolomics based on ultra-high performance liquid chromatography-quadrupole orbitrap mass spectrometry (UPLC-Q-Orbitrap/MS). A total of 82 compounds were identified, including six catechins, nine dimeric catechins, five amino acids, eight alkaloids, eight phenolic acids, three organic acids, two aroma precursors, six N-ethyl-2-pyrrolidinone-substituted flavan-3-ols (EPSF), twenty flavonol/flavone glycosides, ten lipids and five other compounds. Partial least squares discriminant analysis (PLS-DA) and heatmap analysis showed that the chemical composition of sun-dried black tea of different ages was greatly different, with 66 significantly differential compounds being identified between groups (P < 0.05). The contents of catechins, dimeric catechins, amino acids and most flavonol-O-glycosides decreased after storage, while the contents of caffeine, flavone glycosides and six EPSF compounds increased. The Pearson correlation coefficients of the contents of EPSF compounds with storage time were 0.802–0.986, indicating that the contents of EPSF compounds increased in a linear manner during storage. This study can provide a theoretical basis for the elucidation of the chemical composition of sun-dried black tea and for its scientific storage.