茶叶萎凋过程中氨基酸和多酚在叶茎内的时空变化特征

摘要/Abstract

摘要： 叶茎内的氨基酸和多酚在萎凋过程中的变化对于形成茶叶风味物质至关重要。系统解析了叶片和嫩茎中氨基酸和多酚的差异积累模式以及在萎凋过程中的变化特征。结果显示,在萎凋过程中叶片的酚氨比为4.66~6.36,高于嫩茎（1.97~2.59）;嫩茎中游离氨基酸总量显著高于鲜叶,嫩茎中游离氨基酸占干质量的7.44%,叶片中游离氨基酸占干质量的2.22%。鲜叶和嫩茎间存在44个差异积累的氨基酸及其衍生物,其中3个非蛋白质氨基酸（茶氨酸、氨基丁酸和豆叶氨酸）在嫩茎中高积累;叶片和嫩茎中茶多酚含量无显著差异,但存在97个差异积累的多酚类物质,酯型儿茶素和大部分黄酮及黄酮苷在叶片中相对高积累,而非酯型儿茶素在嫩茎中相对高积累。萎凋过程中叶片内游离氨基酸总量上升,而嫩茎中游离氨基酸总量持续下降,叶片和嫩茎中分别有21个和15个氨基酸类物质的含量在萎凋过程中显著变化;叶片和嫩茎中多酚总量变化趋势较为一致,分别存在49个和35个多酚类物质的含量在萎凋过程中显著变化。研究结果表明茶叶原料的叶茎比例对于后续加工中茶叶品质的形成具有重要影响,该研究为基于原料叶茎考量的萎凋调控技术开发提供了理论依据。

关键词: 代谢组学, 萎凋, 叶茎, 游离氨基酸, 茶多酚

Abstract: Changes in amino acids and polyphenols in leaves and stems during withering are critical for the formation of the material basis of tea flavor. This study systematically analyzed the differential accumulation patterns of amino acids and polyphenols in tea leaves and stems , as well as their changes during withering. The results show that the phenol-ammonia ratio in the leaves (4.66-6.36) was higher than that in the stems (1.97-2.59) during withering. The free amino acid content in tender stems (7.44%) was significantly higher than that in fresh leaves (2.22%). A total of 44 amino acids and their derivatives show differential accumulation between the two tissues, of which three (theanine, aminobutyric acid, and pipecolic acid) were found to be highly accumulated in the stems. No significant difference in total tea polyphenol content was observed between fresh leaves and tender stems. However, 97 polyphenolic compounds show differential accumulation between the two tissues. Gallate-type catechins and most flavonols and flavonol glycosides were more highly accumulated in the leaves, whereas non-gallate-type catechins were more abundant in the stems. During the withering process, the total content of free amino acids increased in the leaves but it continued to decrease in the stems. A total of 21 and 15 amino acids and derivatives underwent significant changes during the withering process in leaves and stems, respectively. The changing trends of tea polyphenol content in leaves and stems were relatively consistent, with 49 and 35 polyphenolic compounds showing significant changes during withering, respectively. The results of this study indicate that the leaf-stem ratio in tea raw materials plays a critical role in the formation of tea quality during subsequent processing, providing a theoretical basis for the development of withering regulation technologies based on leaf-to-stem ratio considerations.

Key words: metabolomics, withering, leaf and stem, free amino acids, tea polyphenols

中图分类号:

程海燕, 屠琳玥, 陈琳, 徐安安, 谢亨通, 徐平. 茶叶萎凋过程中氨基酸和多酚在叶茎内的时空变化特征[J]. 茶叶科学, 2025, 45(2): 303-317.

CHENG Haiyan, TU Linyue, CHEN Lin, XU An'an, XIE Hengtong, XU Ping. Spatiotemporal Changes of Amino Acids and Polyphenols in Leaves and Stems during Tea Withering[J]. Journal of Tea Science, 2025, 45(2): 303-317.

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