Study On Colour And Aroma Of Congou Black Tea

Sichuan congou black tea, Yunnan congou black tea and Keemun black tea are called the three major congou black tea of china. In this research, we studied the aroma and colour characteristics of ten Sichuan congou black tea samples and ten Yunnan congou black tea samples. We made organoleptic evaluation, chromatic difference analysis and GC-MS analysis, then we established aroma quality evaluation models using principal component analysis of Sichuan congou black tea and Yunnan congou black tea, the results obtained are as follows:1. Colour research of congou black teaThe results of organoleptic evaluation and chromatic difference analysis for20tea samples showed that two scores of liquor color evaluation had good consistency. There were also high correlation between L*(an indicator of light and dark), a*(an indicator of red and green), b*(an indicator of yellow and blue) and a*/b*(a derived indicators of a*and b*), which showed the colour difference meter could reappear indicators of the liquor color well.Statistical analysis showed the scores of liquor color were significantly correlative with L*and also had good correlation with b*and a*/b*; Stepwise regression analysis showed that the regression equation of a*/b*had higher determination coefficient; Quadratic polynomial stepwise regression analysis showed the regression equation of a*/b*and L*had a determination coefficient of80%, which can, to some extent, expressed the liquor color of black tea.2. Aroma research of Sichuan congou black teaGC-MS analysis of10Sichuan congou black tea samples isolated and identified163kinds of volatile components, among which were64common components. Principal component analysis of5tea samples which had higher scores in aroma organoleptic evaluation showed the characteristic aroma components were Geraniol, Linalool and its oxides, Neral, trans-2-Hexenal, Isopentyl Formate, Benzyl alcohol, β-Cyclocitral,6-Methyl-5-hepten-2-one, Benzaldehyde, Methyl salicylate, Cis-jasmone,2-Heptanone,3,5-Octadien-2-one,β-Ionone, Hexanoic acid-4-ester hexane, 2,6,6-Trimethyl-1,3-cyclohexadiene-1-carboxaldehyde, Geranylacetone.We used principal component analysis to establish aroma quality evaluation models of Sichuan congou black tea, which have good consistency with organoleptic evaluation. This model had a certain degree of applicability for aroma quality evaluation of Sichuan congou black tea3. Aroma research of Yunnan congou black teaGC-MS analysis of10Yunnan congou black tea samples isolated and identified116kinds of volatile components, among which were48common components. Principal component analysis of5tea samples which had higher scores in aroma organoleptic evaluation showed the characteristic aroma components were Linalool and its oxides.Geraniol, trans-2-Hexenal, Hexanol, trans-2-Nonenal,Methyl palmitate, Nerol, Phytol, β-Damascenone, β-Ionone, Methyl salicylate, trans-Nerolidol, α-Cadinol.We used principal component analysis to establish aroma quality evaluation models of Yunnan congou black tea, which have prominent consistency with organoleptic evaluation. This model had a certain degree of applicability for aroma quality evaluation of Sichuan congou black tea...