Division of Organic Chemistry, National Institute of Health Sciences, Tokyo, Japan.
J Agric Food Chem. 2011 May 25;59(10):5181-7. doi: 10.1021/jf200204y. Epub 2011 Apr 11.
The taste of black tea differs according to the different areas in which the tea is grown, even for the same species of tea. A combination of (1)H NMR spectroscopy and partial least-squares discriminate analysis (PLS-DA) was used to assess the quality differences of tea leaves from four cultivation areas with different elevations, RAN > 1800 m, UDA = 1200 m, MEDA = 600 m, and YATA < 300 m, in Sri Lanka. As a result of a statistical analysis, PLS-DA showed a separation between high- and low-quality black teas derived from the four different tea cultivation areas. RAN from the highest elevation showed characteristic trends in the levels of theaflavin and theaflavin 3,3'-digallate that were found only in RAN, and the levels of theanine and caffeine were higher, and the levels of thearubigins, especially thearubigin 3,3'-digallate, were lower in RAN than in UDA, MEDA, and YATA. The structures of these components were determined by 1D and 2D NMR analyses. These results demonstrate that this method can be used to evaluate black tea quality according to the chemical composition or metabolites, which are characteristic of the tea leaves cultivated in four regions with different elevations in Sri Lanka.
不同产地的红茶味道不同，即使是同一品种的茶叶也是如此。本研究采用 1H NMR 光谱结合偏最小二乘判别分析（PLS-DA）评估了斯里兰卡四个不同海拔种植区（RAN>1800 m、UDA=1200 m、MEDA=600 m 和 YATA<300 m）的茶叶品质差异。统计分析结果表明，PLS-DA 可以区分来自四个不同茶叶种植区的高低品质红茶。来自最高海拔的 RAN 显示出茶黄素和茶黄素 3,3'-二没食子酸酯水平的特征趋势，这些物质仅在 RAN 中发现，而茶氨酸和咖啡因的水平较高，儿茶素类物质，尤其是茶黄素 3,3'-二没食子酸酯的水平在 RAN 中低于 UDA、MEDA 和 YATA。这些成分的结构通过 1D 和 2D NMR 分析确定。这些结果表明，该方法可用于根据化学成分或代谢物评估红茶品质，这些特征是斯里兰卡四个不同海拔种植区茶叶的特征。
