福鼎大白品种不同茶类茶叶香气成分分析

Analysis of Aroma Components of Different Tea Types of Fuding Dabai

为探究福鼎大白(Camellia sinensis(L.)O.Kuntze cv.Fuding Dabai cultivar)品种不同茶类的茶叶香气成分,以福鼎大白品种茶树鲜叶经过相应工艺加工而成的茶叶为原料,通过顶空-固相微萃取-气质联用法(HS-SPME-GC/MS)测定红茶、绿茶和白茶的挥发性香气物质,对检测出的挥发性物质进行主成分分析(Principal Component Analysis,PCA)并建立偏最小二乘-判别模型(partial least square-discriminant analysis,PLS-DA),通过香气活性值(Odor Activity Value,OAV)评价主要化合物对茶香的贡献度。结果表明:共鉴定出43种化合物,以萜类化合物占优势。建立的PLS-DA模型均可靠(R_(X)^(2)=0.996,R_(y)^(2)=0.999,Q^(2)=0.998),可筛选出不同茶类茶叶的主要差异物质为香叶醇、芳樟醇、水杨酸甲酯、反式芳樟醇氧化物(呋喃型)、氧化芳樟醇Ⅰ(顺式)、苯乙醛、苯乙醇、茉莉酮和二苯甲酮。结合OAV分析表明,花香是福鼎大白品种茶叶共有特征,白茶和绿茶两者均具有较类似的花香属性,但白茶的甜花香更明显,而绿茶则偏清花香;红茶因为发酵的工艺而表现出花果香。加工工艺通过影响挥发性香气物质的组成和含量来调控不同茶类的香气,茶树品种和共有的挥发性香气物质决定了茶叶的基本香型,而占优势的挥发性香气物质的比例则使不同茶类呈现出不同的香型。

In order to explore the aroma composition of different tea types of Fuding Dabai,the fresh leaves of Fuding Dabai with certain treatments were collected as raw materials,and the volatile aroma substances of different black tea,green tea and white tea were determined by the solid phase microextraction(SPME)and gas chromatography-mass spectrometry(GC-MS).Then,the PCA(Principal Component Analysis)was performed on the detected volatile substances and the PLS-DA(partial least square-discriminant analysis)was established to evaluate the contribution of the main compounds to the aroma fragrance by the OAV(Odor Activity Value).The results showed that a total of 43 compounds were identified,with terpenoids predominating.The PLS-DA models established were reliable(R_(X)^(2)=0.996,R_(y)^(2)=0.999,Q^(2)=0.998),and the maindifferential substances of different tea leaves was screened,which were geraniol,linalool,menthyl salicylate,(E)-furanold linalool oxide,cis-alpha,alpha,5-trimethyl-5-vinyltetra hydrofuran-2-methabol,2-phenylethanal,2-phenylethanol,(Z)-jasmone and benzophenone.Combined with OAV analysis,it showed that floral fragrance was a common feature of Fuding Dabai teas.Both white tea and green tea had similar floral properties,but white tea had more obvious sweet floral aroma,while green tea had clear floral aroma,and black tea showed floral and fruit aroma because of the fermentation process.The processing process regulated the aroma of different tea species by affecting the composition and content of volatile aroma substances.The tea tree species and the common volatile aroma substances determined the basic aroma of tea leaves,while the proportion of the dominant volatile aroma substances made different teas present different aroma patterns.