Zheng Yanchun, Chen Peifen, Zheng Peng, Chen Jiahao, Sun Binmei, Liu Shaoqun
College of Horticulture, South China Agricultural University, Guangzhou 510642, China.
Foods. 2024 Jan 2;13(1):160. doi: 10.3390/foods13010160.
Winter dry tea (WDT) exhibits a more intense and lasting aroma compared to dry tea from other seasons; however, this conclusion is solely based on sensory outcomes and lacks corroborative theoretical evidence. Our study aimed to analyze the aroma compounds in WDT and investigate the causes behind the formation of WDT's aroma by analyzing the volatile organic compounds (VOCs) in WDT, spring dry tea (SDT), winter fresh leaves (WFLs) and spring fresh leaves (SFLs) by gas chromatography-mass spectrometry (GC-MS), complemented by an analysis of gene expression pertinent to WFLs and SFLs by using transcriptomic analysis. The results revealed a significant increase in total VOCs in WDT compared to SDT, with WDT exhibiting distinct woody aromas as indicated by a higher -muurolene content. In WFL, the contents of aldehydes and ketones were richer than those in SFL. Notably, the study found that UDP-glycosyltransferase genes in WFLs were significantly up-regulated, potentially promoting the synthesis of terpene glycosides. These terpene glycosides can release terpene aroma compounds during processing, contributing significantly to the intense and lasting aroma of WDT. Overall, this research provides valuable insights into the mechanism behind aroma formation in Guangdong oolong tea harvested during winter.
冬干茶（WDT）相比其他季节的干茶，具有更浓郁持久的香气；然而，这一结论仅基于感官结果，缺乏确凿的理论证据。我们的研究旨在分析冬干茶中的香气成分，并通过气相色谱-质谱联用（GC-MS）分析冬干茶（WDT）、春干茶（SDT）、冬鲜叶（WFLs）和春鲜叶（SFLs）中的挥发性有机化合物（VOCs），并辅以转录组分析来研究与冬鲜叶和春鲜叶相关的基因表达，从而探究冬干茶香气形成的原因。结果显示，与春干茶相比，冬干茶中的挥发性有机化合物总量显著增加，其中冬干茶中较高的-榄香烯含量表明其具有独特的木香香气。在冬鲜叶中，醛类和酮类的含量比春鲜叶中的更丰富。值得注意的是，该研究发现冬鲜叶中的UDP-糖基转移酶基因显著上调，这可能促进了萜烯糖苷的合成。这些萜烯糖苷在加工过程中可以释放出萜烯香气化合物，对冬干茶浓郁持久的香气有显著贡献。总体而言，本研究为冬季采摘的广东乌龙茶香气形成机制提供了有价值的见解。
