基于脂质组学的炒青绿茶加工中脂类衍变规律及香气形成的关键脂质前体分子探索

Aroma is one important factor that determines the quality of pan-fried green tea. Lipid oxidation and degradation is one of four main pathways of tea aroma formation during tea manufacturing process. Their end products, odor-active compounds, are highly relevant to the aroma flavor of pan-fried green tea. However, by far studies on tea lipids are very limited. Meanwhile, hampered by analytical approaches, the detailed composition of lipids in pan-fried green tea and their dynamic changes during manufacturing process remain unclear. Furthermore, research on key lipid precursor species for aroma formation has not been reported yet. Therefore it is necessary to develop novel method for large-scale analysis of tea lipids with high sensitivity and structural-specificity. In our previous work, we preliminarily established a tea lipidomics method and tentatively identified over 300 lipid species in pan-fried green tea. Based on this, we intend to further optimize tea lipidomics method, then to study the dynamic changes of tea lipids in the manufacturing process of pan-fried green tea, and moreover to unravel the key lipid precursor species for aroma formation. This study is expected to identify new tea lipids, which could enrich the theoretical basis of lipids in tea aroma formation. Further more, the identification of key lipids precursors of aroma formation may serve as a novel target for aroma flavor manipulation, which could assist the precise aroma manipulation and manufacturing of pan-fried green tea in practical.

香气是决定炒青绿茶品质的重要因子。脂类氧化降解是茶叶加工过程中香气形成的四大重要途径之一，其香气产物与炒青绿茶的香气特征密切相关。然而目前关于茶叶脂质的系统研究较为缺乏。同时，受分析手段之局限，目前炒青绿茶中脂类的详细组成及其在加工中的衍变规律尚未明了，参与香气形成的关键脂质前体分子的探索未见报道。因此有必要发展高灵敏、高特异的茶叶脂类物质分析方法。在前期工作中，申请人已初步建立了基于UPLC-Q-TOF的茶叶脂质组学方法，在炒青绿茶中鉴定出超过300个脂类化合物。本研究拟在此基础上，进一步优化茶叶脂质组学方法；基于该方法，阐明炒青绿茶加工过程中脂类动态衍变规律；筛选与香气形成显著相关的关键脂质前体分子并初步验证。本研究有望鉴定出尚未报道的茶叶脂质组分，充实茶叶加工中香气形成的脂类化学物质基础；筛选所得的关键脂质前体分子，有望作为香气品质调控的新靶标，为炒青绿茶香气的精准调控提供科学支撑。

香气是决定炒青绿茶品质的重要因子。脂类氧化降解是茶叶加工过程中香气形成的四大重要途径之一，其香气产物与绿茶香气密切相关。然而目前关于茶叶脂质的系统研究较为缺乏。同时，受分析手段之局限，目前绿茶中脂类的详细组成及其在加工中的衍变规律尚未明了，参与香气形成的关键脂质前体分子的探索未见报道。本项目建立了非靶向茶叶脂质代谢组学新方法，对绿茶中脂类物质进行了全面的定性定量分析，鉴定出20亚类、283个脂质；系统解析了绿茶加工过程中脂类物质的动态衍变规律，筛选出杀青、毛火工序为绿茶加工中脂类降解关键阶段，涉及叶绿素降解、磷脂酸降解、糖脂降解等代谢通路；初步鉴定出富含亚油酰基FA 18:2的磷脂酸化合物是参与绿茶香气形成的关键脂质前体物质，为绿茶香气的精准调控、定向加工提供科学理论支撑。此外，发展了一种基于离子迁移谱的茶叶香气在线实时检测新技术，并用于绿茶香气的“动态”指纹分析和香型判别，为后续对香气前体物的进一步验证研究做技术储备。