茶树品种香“清香”和“栗香”的化学物质基础研究

Tea germplasm is the material base and one of the most important factors to determine the aroma types of tea products. The difference of the chemical substances base for different tea germplasms will determine inevitably the aroma contents and compositions of tea products and further generate some different aroma types under the same processing technique. Fresh scent flavor and chestnut-like flavor are the two typical aroma types of green tea made from differrent tea germplams which has been verified by tea quality evaluation practice. However, the chemical constituents basis of fresh scent flavor and chestnut-like flavor of green tea based on tea germplasms have not yet been elucidated mainly due to the limitation of the past analysis techniques. With the quick development of the molecular sensory science, the concept of sensomics has been used successfully to ascertain the key aroma components in a variety of foods, which has provided some very important scientific data for food quality control and also offered us a kind of new feasible thinking and reference for the study of the chemical constituents bases of aroma type difference for tea germplasms. In our previous researches, the advanced analytical method of GC×GC-ToF-MS, GC-O and UHPLC-QTOF-MS for tea aroma analysis and chemical components analysis have been established, and some suitable tea germplasms have also been screened and selected. Based on the existing studies, therefore, we are ready to use the concept of sensomics to analyze and identify the key aroma components playing a vital role in the fresh scent flavor and chestnut-like flavor, and use the metabonomics to analyze the difference of their precusor substance and others key chemcail constituents in freash tea leaves. The study has great hopes to illuminate the chemical constituents basis of fresh scent flavor and chestnut-like flavor of green tea based on tea germplasms, and will establish an important theoretic ground to the improvement of the screening efficience of the special germplasms in the earlier stage of tea breeding, the analysis of the qualify manufacturability of different tea germplasms and the development of green tea products with different aroma type.

茶树品种是决定茶叶香型的物质基础和最主要因素之一。不同茶树品种鲜叶在相同的工艺条件下可产生不同的香型，其中"清香"和"栗香"是绿茶的两种典型香型。然而，受以往分析手段等方面的限制，至今尚未查明茶树品种香"清香"和"栗香"的化学物质基础。我们前期的研究已筛选出了一批"清香"和"栗香"香型的茶树品种材料，并建立了GC×GC-TOF-MS、GC-O以及UHPLC-QTOF-MS等先进的茶叶香气及香气前体的分析方法；本研究拟在前期的研究基础上，系统运用"感官组学"方法鉴定出茶树品种香"清香"和"栗香"香型的关键呈香成分，并采用代谢组学手段来研究两种香型茶树品种的香气前体物质及其它关键化学成分的差异。本研究有望探明"清香"和"栗香"两种茶树品种香的化学物质基础，为今后开展不同香型茶树品种的选育、分析茶树品种适制性以及开发不同香型的绿茶产品提供重要的科学理论依据。

茶树品种是决定茶叶香型的物质基础和最主要的因素之一，其中“栗香”和“清香”是绿茶的两种典型的香型，也是绿茶香气品质优异的重要感官评价特征。然而，受以往分析手段等方面的限制，尚未查明茶树品种香“栗香”和“清香”的化学物质基础，这在很大程度上限制了茶叶风味品质化学的研究深入和茶叶加工技术水平的提升。.本项目运用“感官组学”等方法来鉴定茶树品种香“栗香”和“清香”香型的关键呈香成分，并采用代谢组学手段来研究两种香型茶树品种的香气前体物质及其它关键化学成分的差异，旨在阐明茶树品种香的化学物质基础。.本项目建立了GC×GC-TOF-MS和UHPLC-QTOF-MS 等多种先进的茶叶香气及香气前体的分析方法；采用这些方法，从55个代表性西湖龙井茶样品中鉴定出了478个共有香气成分；查明了6个茶树良种（龙井长叶、龙井群体种、龙井43、乌牛早、迎霜以及鸠坑群体种）制备的龙井茶的香气成分的差异情况；系统运用“感官组学”方法鉴定出了绿茶“清香”和“栗香”香型的关键呈香成分，研究发现，反式-β-紫罗兰酮、庚醛、2-戊基呋喃、反,反-3,5-辛烯-2-酮、顺式-己酸-3-己烯酯、乙苯、苯乙醛及芳樟醇等为绿茶“栗香”的关键呈香成分；而己醛、乙基苯、2-戊基呋喃、苯乙醛、芳樟醇、壬醛、萘、香叶醇、顺-3-己烯酸己烯酯及反式-β-紫罗兰酮等为绿茶“清香”的关键呈香成分，并采用香气重组实验初步验证了“清香”香型；此外，本项目还查明了加工过程中关键香气化合物的形成变化规律，并鉴定出22个香气糖苷前体物质等。.本资助项目查明了茶树品种香“清香”和“栗香”的重要化学物质基础；相关研究成果可为今后开展不同香型茶树品种的选育、分析茶树品种适制性以及开发不同香型的绿茶产品的定向加工技术研发等提供重要的科学依据。在本资助项目的支持下，项目组成员先后在本领域国内外的重要学术期刊上发表相关研究论文11篇，其中SCI论文6篇，EI收录2篇；授权国家发明专利1项（ZL201710058036.9）。