Black tea. During the processing of black tea, a chemical reaction centered on the enzymatic oxidation of tea polyphenols takes place. The composition of fresh leaves changes greatly, and tea polyphenols are reduced by more than 90%. New components and aroma substances such as theaflavins and thearubigins are produced, which are characterized by black tea, red soup, red leaves, and sweet and mellow taste. Qimen black tea is the most famous black tea variety.