Affiliation:
1. 1Western Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, 800 Buchanan Street, Albany, California 94710, USA
2. 2Department of Food Service Industry, Uiduck University, Gyongbuk, 780-713, Korea
Abstract
We evaluated the antimicrobial activities of seven green tea catechins and four black tea theaflavins, generally referred to as flavonoids, as well as the aqueous extracts (infusions) of 36 commercial black, green, oolong, white, and herbal teas against Bacillus cereus (strain RM3190) incubated at 21°C for 3, 15, 30, and 60 min. The results obtained demonstrate that (i) (−)-gallocatechin-3-gallate, (−)-epigallocatechin-3-gallate, (−)-catechin-3-gallate, (−)-epicatechin-3-gallate, theaflavin-3, 3′-digallate, theaflavin-3′-gallate, and theaflavin-3-gallate showed antimicrobial activities at nanomolar levels; (ii) most compounds were more active than were medicinal antibiotics, such as tetracycline or vancomycin, at comparable concentrations; (iii) the bactericidal activities of the teas could be accounted for by the levels of catechins and theaflavins as determined by high-pressure liquid chromatography; (iv) freshly prepared tea infusions were more active than day-old teas; and (v) tea catechins without gallate side chains, gallic acid and the alkaloids caffeine and theobromine also present in teas, and herbal (chamomile and peppermint) teas that contain no flavonoids are all inactive. These studies extend our knowledge about the antimicrobial effects of food ingredients.
Publisher
International Association for Food Protection
Subject
Microbiology,Food Science
Cited by
152 articles.
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