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To investigate the difference in aroma between high aroma black tea and traditional congou black tea, electronic nose and GC-MS were used to investigate the key factors that differentiated the aroma quality of high aroma black tea from traditional congou black tea. The results showed that the high aroma black tea had a predominantly floral aroma, while the traditional congou black tea aroma presented a sweet aroma. GC-MS detected 78 volatile substances in the two black teas, among which linalool oxide, linalool, methyl salicylate, pentanol, 2-cyclopropylethanol, (-)-carveol, β-cyclocitral, 2-ethylfuran, 1,3,8-menthatrien and 1,4-pentadiene were important aroma components to distinguish the different flavours of black tea. The total of the response values of the electronic nose detection of traditional congou black tea was significantly higher than that of high aroma black tea. The multivariate statistical analysis allowed S6 and S10 electrode signals for the identification of different flavours of black tea, and predicted that 1,4-pentadiene was an important volatile substance for the identification of different flavours of black tea. The results confirmed the aroma composition characteristics of high fragrant black tea and distinguished it from traditional congou black tea, and would provide a theoretical basis for further classification of different flavor black tea.

In order to explore the origin differences of black tea metabolites, the metabolites in black tea produced in Fu 'an and Youxi of Fujian province were compared and analyzed by using sensory evaluation method and extensive targeting metabolomic determination method of ultra-performance liquid chromatography-mass spectrometry (UPLC-MS/MS). The results showed that, Fu'an black tea mainly tasted of “mellow and soft”, while Youxi black tea of “mellow and sweet”. A total of 937 metabolites including of flavonoids, phenolic acids, lipids, organic acids, amino acids and their derivatives were identified by metabonomics in the black tea of the two regions, through the principal component analysis (PCA) and orthogonal partial least-squares discriminant analysis (OPLS-DA) could significantly distinguish different producing area of black tea, and identified 410 species of metabolites with significant difference. The relative content of 291 different metabolites in Youxi black tea was higher than that of Fu 'an black tea, among which Astragalin, EC, L-glutamine, L-aspartic acid, L-lysine, L-tryptophan, L-glutamic acid, chlorogenic acid, phenethylamine, vitexin-2''-O-rhamnoside might have important contributions to the formation of different taste and quality of black tea from the two regions. Metabolic pathway analysis showed that the metabolism levels of amino acids and flavonoids of black tea between the two places were significantly different, which might be the reason for the difference in the taste and quality of black tea between the two places. The research would provide a theoretical basis for the identification of tea origin.