National Agriculture and Food Research Organization, National Food Research Institute.
J Oleo Sci. 2022 Sep 1;71(9):1413-1419. doi: 10.5650/jos.ess22135. Epub 2022 Aug 15.
Green tea is a popular refreshing drink with several functional properties attributed to its bioactive compounds. The bioactive content and composition vary with several factors. Several advances in chromatographic studies have facilitated the study of chemical composition of green tea leaves; however, the content of organic acids, particularly quinic acid, has not been explored fully. Therefore, changes in the content of organic acids, including quinic acid, in green tea leaves, were investigated in this study. All the studied varieties contained large amounts of quinic and oxalic acids. Kukicha and Matcha contained the highest and lowest amounts of quinic acid, respectively. Furthermore, high-grade Matcha had a significantly lower quinic acid content than low-grade Matcha. The Asatsuyu sample had the lowest quinic acid content in 2018 and 2019 compared with the other green tea varieties. The content of quinic acid increased with maturity, but that of oxalic, malic, succinic, and citric acids decreased after a slight increase. Shading cultivation in Saeakari significantly lowered the quinic acid content and slightly increased the content of malic, citric, and oxalic acids. Malic acid and citric acid content in Yabukita changed with sunrise and sunset, but that of other organic acids did not show any considerable change. These results show that using an appropriate plucking time could lead to further improvement in the quality of green tea leaves. Overall, green tea is a good source of quinic acid, which will attract attention in future functional research on this drink.
绿茶是一种受欢迎的清爽饮品，具有多种生物活性化合物赋予的功能特性。生物活性含量和组成因多种因素而异。色谱研究的几项进展促进了对绿茶叶片化学成分的研究；然而，有机酸，特别是奎尼酸的含量尚未得到充分研究。因此，本研究调查了绿茶叶片中有机酸（包括奎尼酸）含量的变化。所有研究的品种都含有大量的奎尼酸和草酸。玉露和抹茶分别含有最高和最低量的奎尼酸。此外，高级抹茶的奎尼酸含量明显低于低级抹茶。与其他绿茶品种相比，Asatsuyu 样品在 2018 年和 2019 年的奎尼酸含量最低。奎尼酸含量随成熟度增加而增加，但草酸、苹果酸、琥珀酸和柠檬酸含量在略有增加后下降。在 Saeakari 进行遮荫栽培可显著降低奎尼酸含量，并略微增加苹果酸、柠檬酸和草酸含量。Yabukita 中的苹果酸和柠檬酸含量随日出和日落而变化，但其他有机酸含量没有明显变化。这些结果表明，选择适当的采摘时间可以进一步提高绿茶叶片的品质。总的来说，绿茶是奎尼酸的良好来源，这将在未来对这种饮料的功能研究中引起关注。
