Effects of Freezing on the Fermentation and Speed of Infusion of Congou Black Tea

The effects of freezing on the fermentation and speed of infusion of congou black tea was studied.Congou black tea from the fresh and withering tea leaves was performed as follows: deep freezing at -17 ℃ for 2 h,then thawing,rolling,fermenting and drying.The results showed that the activity of tea polyphenol oxdase was reduced by 32.9% and 33.3% respectively when treated with the freezing on the fresh and withering tea leaves.And the percentage of broken tea leaf cells increased from 95.2% to 99.3% on the withering and rolling tea leaves, the speed of black tea fermentation also increased from 4 h to 2 h.The content of tea polyphenols decreased by 8.4%.The content of amino acid only increased by 0.7%,while the content of water extracted substances,theaflavins(TFS),thearubigins(TRS) increased by 7.9%,25.8% and 38.3% respectively.Therefore,freezing on the withering tea leaves can improve the quality of congou black tea,as well as accelerate the infusion speed of congou black tea compounds.