Shaking the tea leaves is the key manipulation to making oolong tea. It contributes to the formation of flavor and fragrance in oolong tea. The dynamic variations of catechins and volatile organic compounds (VOCs) during the shaking process were investigated. The results showed that the contents of epicatechin, epigallocatechin, epicatechin gallate (ECG), and epigallocatechin gallate (EGCG) first decreased after the shaking and then increased to the initial value before the next shaking. Geraniol, linalool and its oxides, and phenylethyl alcohol showed similar variations. The contents of trans-β-ocimene, 1H-indole, and 3-hexenyl hexanoate increased after the second or third shaking (the late fermentation stage). However, the contents of aldehydes showed an opposite trend to other VOCs. The abundance of phenylethyl alcohol was positively related to the content of ECG and EGCG ​during fermentation, whereas the abundance of cis-3-hexenal was negatively related to the content of ECG. The correlations between catechin and VOCs indicated that shaking affected the chemical transformation of the compounds in oolong tea.

中文翻译：

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摇晃工艺对乌龙茶中儿茶素与挥发物相关性的影响

摇动茶叶是制作乌龙茶的关键操作。它有助于乌龙茶风味和香味的形成。研究了振荡过程中儿茶素和挥发性有机化合物（VOCs）的动态变化。结果表明，表儿茶素、表没食子儿茶素、表儿茶素没食子酸酯（ECG）和表没食子儿茶素没食子酸酯（EGCG）的含量在震荡后先下降，然后在下一次震荡前上升到初始值。香叶醇、芳樟醇及其氧化物和苯乙醇表现出类似的变化。在第二次或第三次摇动（发酵后期）后，反式-β-罗勒烯、1H-吲哚和3-己烯基己酸酯的含量增加。然而，醛类的含量与其他 VOCs 呈现相反的趋势。苯乙醇的丰度与发酵过程中心电图和EGCG的含量呈正相关，而cis-3-己烯醛的丰度与心电图的含量呈负相关。儿茶素和VOCs的相关性表明摇晃影响了乌龙茶中化合物的化学转化。