Analysis and Discrimination of Aroma Compounds of Guire 2 Black Tea Treated with Different Drying Methods

Objective:The mainly different aroma components of Guire 2 black tea treated with different drying methods were identified to determine the drying methods of black tea. Methods:Solid phase microextraction coupled with gas chromatography-mass spectrometry(SPME-GC-MS)was used to identify the aroma components of Guire 2 black tea samples dried by freeze drying(D),hot air drying(H),sun drying(S),freezing+hot air drying(DH). Principal component analysis(PCA)and sensory evaluation were used to analyze the aroma characteristics. Orthogonal signal corrected least squares discriminant analysis(OPLS-DA)was used to analyze the differences between groups. Cluster analysis(HCA)was used to identify the drying methods of black tea. Results:A total of 36 aroma components were identified,among which the relative contents of 12 aroma components were relatively high,which constituted the base of sweet scent of Guire 2 black tea. Three principal components were extracted by PCA(the fraction of the variation of the X variables explained was 82.2%),and the caffeine,nerol,linalool and so on had a greater impact on the component group. The OPLS-DA analysis had a poor fit to the model between DH and H,and the other groups had a good fit. The difference components were caffeine and linalool(D and DH),caffeine and nerol(D and H,D and S),linalool and nerol(DH and S),benzyl alcohol(H and S). The results of HCA cluster analysis showed that the high discrimination could be achieved except DH and H. Conclusions:The aroma components of Guire 2 black tea could be identified and classified by GC-MS combined with PCA,OPLS-DA and HCA. A comprehensive evaluation indicated that freezing+hot air drying showed the best effect.