Thearubigins

The complex, polymeric flavonoid pigments that give black tea its deep reddish-brown colour, full flavour, and body. Thearubigins arise from extensive oxidation and polymerization of catechins during fermentation, complementing the brighter theaflavins; together the two groups define black-tea liquor character. Their astringency and colour strength guide blenders building consistent breakfast blends. As chemical markers of manufacture quality, thearubigin levels help graders and buyers value teas, while their antioxidant capacity adds to tea’s standing as a major dietary source of polyphenols.