清香型乌龙茶品质形成过程中香气组成化学模式的动态变化规律

分别以金观音和黄观音品种春茶新梢为供试材料,对香气成分在茶树新梢生育及清香型乌龙茶制作过程中的含量变化进行GC-MS检测分析。结果表明,供试鲜叶及清香型乌龙茶在制品共可检出香气成分365种,其与癸酸乙酯峰面积比值经数据标准化预处理后,再行相似度分析(夹角余弦)、聚类分析(欧氏距离-近邻法)和主成分分析,均可获得较为一致的可视化模式识别结果。金观音和黄观音茶样可按品种划分成两个类群,不同生育期芽叶香气组成化学模式存在较大差异,且能与清香型乌龙茶在制品进行较好区分。金观音和黄观音茶样的橙花叔醇、香叶醇、法呢烯和植醇等香气成分含量有较大差异。香叶醇和芳樟醇伴随茶树新梢生育呈递减趋势;橙花叔醇、吲哚和法呢烯在清香型乌龙茶制作过程中大幅增加。由此可见,清香型乌龙茶香型品质的形成不仅与茶树品种和芽叶嫩度有关,还受制茶工艺技术的影响。

Dynamic Variation of Chemical Pattern Related to Aroma Constituents during the Quality Formation of Fresh Scent-Flavor Oolong Tea

The spring shoots harvested from the buds of Jinguanyin and Huangguanyin tea plant(Camellia sinensis) were used as materials for the experiments,and aroma constituents of the samples prepared during the period of shoot growth and the process of fresh scent-flavor Oolong tea were determined by gas chromatography-mass spectrometry.There were 365 aroma compounds detected in all tea samples.When given data standardization to the peak area ratios between aroma compounds and ethyl decanoate,the consistent results would be obtained based on visualized pattern recognition,which included cosine similarity analysis,nearest-neighbor cluster analysis(Euclidean distance) and principal component analysis.All tea samples could be divided into two groups according to tea cultivars.One was made up of the samples of Jinguanyin,and the other came from the samples of Huangguanyin.The chemical patterns of the aroma constituents in spring shoots were so much different that they could be well distinguished from the samples of fresh scent-flavor Oolong tea.The samples of Jinguanyin and Huangguanyin were very different in contents of nerolidol,geraniol,farnesene,phytol,etc.The contents of geraniol and linalool decreased following with shoot growth,whereas the contents of nerolidol,indole and farnesene increased obviously during the process of fresh scent-flavor Oolong tea.These facts suggested that the aroma quality of scent-flavor Oolong tea was not only involved with tea cultivars and shoot maturity,but also affected by its manufacturing process.