Submitted to: Journal of Agriculture and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/16/2005
Publication Date: 10/15/2005
Citation: Friedman, M., Kim, S., Lee, S., Han, J., Lee, K., Kozukue, N. 2005. Catechin, theaflavin, caffeine, and theobromine content in 38 commercial teas and green tea extracts determined by hplc.. Journal of Agriculture and Food Chemistry. 70:C550-559.
Interpretive Summary: All plants, including tea leaves, produce secondary metabolites, organic compounds that are involved in the defense of the plants against invading pathogens, including insects, bacteria, fungi, and viruses. In the case of tea leaves, these metabolites include polyphenolic compounds, the so-called catechins and theaflavins and the alkaloids caffeine and theobromine. As part of an effort designed to define antibiotic activities of naturally occurring compounds and plant extracts against foodborne pathogenic bacteria, we developed and used an HPLC assay to measure the content of 13 tea compounds in 38 commercial teas and green tea extracts sold in the Albany-San Francisco area of California. The results of this collaborative study (carried out at the College of Human Ecology, Yeungnam University, Korea) show that there is wide variation in the content of antibiotic catechins and theaflavins among the black, green, jasmine, oolong, and herbal teas and green tea extracts evaluated. Teas and tea extracts containing high levels of these compounds are a source of naturally occurring antibiotic compounds that may protect foods, feeds, and consumers against contamination by pathogenic bacteria.
Technical Abstract: Tealeaves contain compounds that exhibit antibiotic and other beneficial effects. To help define the composition of teas consumed in the United States, we developed and used an HPLC method to analyze the content of catechins, theaflavins, caffeine, and theobromine in 12 black teas, 11 green teas, four green tea extracts, three jasmine teas, two oolong teas, and six herbal and other teas. The following ranges were observed in the content of the 13 tea components of the 38 samples evaluated (in mg/g): (')-epigallocatechin, 0-27.5; (')-catechin, 0-3.99; (+)-epicatechin, 0-6.14; (')-epigallocatechin gallate, 0-61.8; (')-gallocatechin gallate, 0-15.6; (')-epicatechin gallate, 0-31.7; (')-catechin gallate, 0-0.50; theaflavin, 0-3.46; theaflavin-3-gallate, 0-3.06; theaflavin-3'-gallate, 0-7.37; theaflavin-3, 3'-digallate, 0-7.40; caffeine, 0-25.4; and theobromine, 0-6.29. The data also show that (a) with the exception of caffeine, there was wide variation in the composition of the tea compounds within each tea category; (b) black teas contained theaflavins and low amounts of catechins while green teas contained catechins and trace amounts of theaflavins; and (c) herbal teas contained low or zero amounts of catechins and theaflavins, low levels of caffeine, and no theobromine. The results from this and related studies may make it possible for consumers to select teas and tea extracts containing high levels of health-promoting catechins and theaflavins and avoid those containing low amounts of these compounds.