Analysis On The Volatile Constituents And Sensory Attributes Of Oolong Tea

Oolong tea is one of six major teas of our country, which belongs to half fermented tea .It is mainly produced in Fujian, Guangdong and Taiwan. Oolong tea is a special type of tea differentiating with other types by its fruit smell and characteristic fragrance.Its high content of aroma oil is similar with that of flowers ,which attracts experts' notions from domestic and abroad.The aroma of tea is the important target which forms the flavor characterstic and determines the value of tea.The research on it is also an important object in the study of quality.It is certainly the key standard judging ihe quality of Oolong tea.In this research,with the 31 samples of Oolong tea such as Tie guan-yin ,Shuixian,Wuyi rock tea,Da hong-pao,Tie luo-han ,Lang cai,Fenghuang dancong,Dongding and Cuiyu.etc.we applied profile analysis with the evaluation of quanlity of aroma.Aromatic constients were extracted by SDE and then were detected by GC/MS.Meanwhile,the results of sensory descriptive analysis and the ones of GC/MS were applied to Statistical Package for the Social Sciences respectively with the method of principal component analysis.The results are as follows:1.139 aromatic constients are identified in the 31 samples including 33 hudrocarbons,24 alcohols, 16 aldehydes, 13 ketones,2 acids,38 esters and 13 other compounds.2.As far as the category is concerned ,terpene,ester and enol are the typical components in the fragrance of Oolong tea.These main components are linalool and its oxide, beta.-Ionone, alpha.-Farnesene, nerolidyl acetate, pyridine, 3-(phenylmethyl)-, phthalic acid, dibutyl ester, pivalic acid, 2-phenylethyl ester, (Z)-hexanoic acid, 3-hexenyl ester, Phytol and etc. Each type of Oolong tea has its inherent tax fragrant ingredients,which decides its fragrance difference.3.Oolong tea in different season has the difference in the fragrance ingredient composition and the quantity. Hudrocarbon and ester are typical in the spring tea of Sijichun. Hudrocarbon ,ester and other compounds are typical in summer tea and in autumn tea. Hudrocarbon ,ester,alcohol and other compounds are typical in winter tea ,and acids exist in winter tea only.4.The data of GC/MS analysed with PCA,it shows The first principal components represent nerolidyl acetate and alpha.-farnesene. The second principal components represent...