State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, 130 Changjiang West Road, Hefei 230036, Anhui, PR China; Tea Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 310008, Zhejiang, PR China.
Tea Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 310008, Zhejiang, PR China.
Food Res Int. 2022 Dec;162(Pt B):112099. doi: 10.1016/j.foodres.2022.112099. Epub 2022 Nov 2.
Strip green tea (SGT) is widely distributed in China owing to its unique appearance and aroma but the evolution and formation mechanisms of volatile metabolites (VMs) during SGT processing, and especially in the unique process of rubbing, remain unclear. In this study, based on untargeted metabolomics, 217 VMs (8 categories) were identified, and fixation and rubbing processes were found to be key for SGT aroma formation. Moreover, targeted metabolomics was applied to obtain 38 differential VMs and their related substances, of which fatty acid-derived volatiles (14 VMs) and glycoside-derived volatiles (8 VMs) showed significant contributions to SGT aroma, and their derivation laws during SGT manufacturing were clarified. Furthermore, the effect of rubbing degree on volatile metabolite formation was explored, and 11 key differential VMs were screened by variable importance in projection, and odor activity value analyses. Appropriate rubbing promoted the loss of grassy VMs (such as 1-octanol and 2-pentyl-furan) and enrichment of floral/fruity VMs (such as trans-β-ionone, nonanal, geraniol, citral, (Z)-3,7-dimethyl-2,6-octadien-1-ol, and (Z)-hexanoic acid, 3-hexenyl ester). Our study not only enriches the chemical theory of green tea processing but also provides technical support for the precision directional processing of high-quality SGT.
绿茶（SGT）因其独特的外观和香气而在中国广泛分布，但 SGT 加工过程中挥发性代谢物（VMs）的演变和形成机制，特别是在独特的揉捻过程中，仍不清楚。在本研究中，基于非靶向代谢组学，鉴定出 217 种 VMs（8 类），发现固定和揉捻过程是 SGT 香气形成的关键。此外，应用靶向代谢组学获得了 38 种差异 VMs 及其相关物质，其中脂肪酸衍生的挥发物（14 种 VMs）和糖苷衍生的挥发物（8 种 VMs）对 SGT 香气有显著贡献，并阐明了它们在 SGT 制造过程中的衍生规律。此外，还探讨了揉捻程度对挥发性代谢物形成的影响，通过投影变量重要性分析和气味活性值分析筛选出 11 种关键差异 VMs。适当的揉捻促进了青草味 VMs（如 1-辛醇和 2-戊基呋喃）的损失和花香/果香 VMs（如反式-β-紫罗兰酮、壬醛、香叶醇、柠檬醛、（Z）-3,7-二甲基-2,6-辛二烯-1-醇和（Z）-己酸 3-己烯酯）的富集。本研究不仅丰富了绿茶加工的化学理论，也为高品质 SGT 的精准定向加工提供了技术支持。
