role of (-)-epicatechin and polyphenol oxidase in the coupled oxidative breakdown of theaflavins
An enzymic in-vitro model tea fermentation system has been used in combination with gradient elution reversed-phase HPLC to study the oxidative breakdown of black tea theaflavins in the presence and absence of (-)-epicatechin. It was found that theaflavin, theaflavin-3-monogallate, theaflavin-3'...
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Veröffentlicht in: | Journal of the science of food and agriculture 1993, Vol.63 (4), p.435-438 |
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Sprache: | eng |
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Zusammenfassung: | An enzymic in-vitro model tea fermentation system has been used in combination with gradient elution reversed-phase HPLC to study the oxidative breakdown of black tea theaflavins in the presence and absence of (-)-epicatechin. It was found that theaflavin, theaflavin-3-monogallate, theaflavin-3'-monogallate and theaflavin-3,3'-digallate were not substrates for tea polyphenol oxidase (EC 1.14.18.1) whereas (-)-epicatechin alone, or mixtures of (-)-epicatechin and a theaflavin were rapidly converted to a complex mixture of thearubigin-like substances. While the chromatographic profiles varied with the identity of the theaflavin precursor each resembled the equivalent profile obtained with a whole black tea liquor. It is concluded that theaflavins are degraded by a coupled oxidation with (-)-epicatechin-quinone. It is suggested that thearubigins may form via these pathways during black tea manufacture. |
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ISSN: | 0022-5142 1097-0010 |
DOI: | 10.1002/jsfa.2740630409 |