Analysis of the Quality Characteristics of Hunan Black Tea and the Establishment of Its Grade Discrimination Model

26 black tea samples from Hunan province were collected for sensory evaluation, quality analysis and the construction of a typical discriminant model. The results showed that premium black tea contained the most key quality ingredients, such as tea polyphenols, free amino acids, caffeine, and theaflavins, followed by first grade black tea and second grade black tea. There were no significant differences in the contents of free amino acids, theanine, and EGC in the different grades of Hunan black tea, but there were significant (P<0.05) differences in the contents of EC, EGCG, TF-3G, and TF-3'G between any two grades. The typical discriminant analysis had better accuracy for the classification of different grades of Hunan black tea. The accuracy rate of its own verification method was 100% while the interactive verification method had 84.62% accuracy. Through the analysis of the quality and chemical characteristics of different grades in Hunan Gongfu black tea and the construction of a typical discrimination model, the study would provide a reasonable quantitative method for the classification of Hunan black tea.