Study on Flavour Chemistry of Eucommia Tea Ⅲ. Influence of Second Drying on Quality and Flavour Composition of Eucommia Black Tea

The effects of different temperature (95, 110, and 125 ℃) and duration (1, 2, and 3 hours) of second drying on the quality and composition of Eucommia black tea during refining process were studied. It is showed that the contents of protein, amino acid, reduced sugar, theaflavins (TFs) and flavonides decreased with the temperature increasing and duration prolonging. The content of thearubigins (TRs) increased at 95 ℃ and decreased at 125 ℃ with the duration prolonging, and the highest content of TRs was found at 110℃ for 2 h. The content of amodori compounds increased in the first hour of second drying with lower range at 95 ℃ than at 110℃ and 125 ℃, but it decreased later, and the lower the temperature, the faster the decreasing. With organoleptic evaluation on the comprehensive quality, it showed that second drying for 1 to 2 hours under the temperature of 110℃ benefits the formation of high quality Eucommia black tea.