A strong cup of tea usually contains around 180- 240mg of polyphenol compounds, Compounds called catechins are the building blocks of black tea polyphenols they are oxidised to form theaflavins and thearubigens. Thea flavins comprise 3-5% of black tea, and are responsible for its red-orange appearance. Thearubigens' is the term for a wide range of whose structures remain largely polyphenols unknown, but they are also thought to contribute to tea's colour taste.