A Survey of Catechins Contents of Different Green Teas Currently Available in the UK market

The level content of the main flavanols in green tea (i.e. epi-structured catechins) in regular commercial green tea bags commonly consumed in the United Kingdom (UK)have been examined using reversed-phasehigh-pressure liquid chromatography (RP-HPLC). Tea bags were purchased from different local supermarkets in the UK and extracted with natural mineral water at temperature 100°C for 9 minutes at the pre-adjusted pH 4.The level of four catechins (Epi-structured)for the fourteen types of green teawere separated and determinedby HPLC analysis,i.e. ()-epigallocatechin (EGC), ()-epicatechin (EC), ()-epigallocatechin-3-gallate (EGCG) and ()-epicatechingallate (ECG). The standard graphs were validated using certified reference catechins supplied by the Laboratory of the Government Chemist (LGC).The levels of total catechins and oxygen radical absorbance capacity (ORAC) values varied from 96.38 to 205.03 mg/g, 1097.30 - 3421.14Trolox equivalents/g tea bags for fourteen types of green teas respectively.It was evident from the results of this study that there was significant linear and positive correlation (r = 0.932, df = 13, p 0.05) is found to exist between the total catechins contents and ORACvalues.It couldbe concluded that the developed HPLC method gave reliable results for catechins measurementscoupled to this; the well-known ORAC assay was successfully adapted to measure the antioxidant capacity of the green tea extracts throughout this study. Moreover, the higher the level of catechins the greater is the antioxidant capacity of the tea. However,the differences between the studied brands are owing to production, shelf life and storage conditions.