Tea's phenol levels identified

Related tags Green tea Caffeine

Researchers at the University of Leeds have published information
on the levels of phenols, catechins and caffeine found in the most
popular teas consumed in the UK.

Levels of total phenols, catechins and caffeine in teas commonly consumed in the UK have been identified by scientists at the University of Leeds, UK.

Researchers at the Procter Department of Food Science used reversed phase HPLC to achieve their results, reports Reading Scientific Services this week.

According to the article, the research findings revealed that Japanese green tea contained the lowest levels of total phenolics. Major catechins were present in lower levels in most black teas with the exception of Darjeeling and Ceylon teas, which is attributed by the authors to differing fermentation processes.

Catechin levels reported for black teas ranged from 5.6 - 47.5 mg/g. In green teas catechin levels ranged from 51.5 - 84.3 mg/g, with epigallocatechin gallate (EGCG) being the main catechin in Chinese and Indian green teas. The caffeine content of black teas was 25 - 28 mg/g except for Darjeeling (22 mg/g). Instant teas contained 36.9 - 38.3 mg/g caffeine, green teas 11-20 mg/g and decaffeinated teas about 2.7 mg/g of caffeine.

The Tea Council reports that tea consumed in the UK is imported primarily from India and Kenya, with annual consumption amounting to 148,000 tonnes. The RSSL story notes that if future commercial exploitation of tea depends partly on its nutraceutical or therapeutic properties, a knowledge of the actual levels of bioactive compounds in the various different types and brands consumed is essential.

The teas studied were purchased as bags or loose leaf tea from supermarkets and specialised tea outlets in the UK and included PG-Tips, Yorkshire Gold, Ceylon, Darjeeling (all black teas) and green teas from India, China (Chum Mee) and Japan (Bandia). Oolong, fruit and instant teas were also examined.

Full findings are published in a recent publication of the Journal of Agriculture and Food Chemistry 2002, 50: 565-570.

Related topics Research

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