Theaflavins

Theaflavins are born from the enzymatic oxidation of catechins during black tea processing. When polyphenol oxidase catalyzes the reaction, pairs of catechins fuse to form four main theaflavin compounds: TF1 through TF4, each with slightly different properties. Together they account for 1-2% of black tea's dry weight but exert a disproportionate influence on quality. Theaflavins are responsible for the brisk, mouth-drying sensation prized in Assam and Kenyan black teas, as well as the golden-orange ring that appears at the edge of a well-brewed cup. Tea tasters use this ring as a visual quality indicator — a bright, prominent ring suggests high theaflavin content and superior leaf quality. Research has identified theaflavins as potent antioxidants in their own right, with studies suggesting benefits for cholesterol metabolism and cardiovascular health. The ratio of theaflavins to thearubigins (TF:TR) is a critical quality metric in the black tea trade: a higher TF:TR ratio indicates a brighter, more brisk tea, while lower ratios suggest a smoother, heavier character.