Total Phenol, Catechin, and Caffeine Contents of Teas Commonly Consumed in the United Kingdom
Levels of total phenol, catechins, and caffeine in teas commonly consumed in the United Kingdom have been determined using reversed phase high-performance liquid chromatography. Tea bags or tea leaves were purchased from local supermarkets and extracted in boiling water for 5 min. The resulting data showed considerable variability in both total phenols [80.5−134.9 mg/g of dry matter (DM) in black teas and 87−106.2 mg/g of DM in green teas] and catechins (5.6−47.5, 51.5−84.3, and 8.5−13.9 mg/g of DM in black, green, and fruit teas, respectively); this was most probably a result of differing agronomic conditions, leaf age, and storage during and after transport, as well as the degree of fermentation. Caffeine contents of black teas (22−28 mg/g of DM) were significantly higher than in less fermented green teas (11−20 mg/g of DM). The relative concentration of the five major tea catechins ranked EGCG > ECG > EC > EGC > C. The estimated U.K. dietary intakes of total tea catechins, calculated on the basis of an...