title: Identification of the astringent taste compounds in black tea infusions by combining instrumental analysis and human bioresponse.
abstract: Application of taste dilution analyses on freshly prepared black tea infusions revealed neither the high molecular weight thearubigen-like polyphenols nor the catechins and theaflavins, but a series of 14 flavon-3-ol glycosides as the main contributors to the astringent taste perceived upon black tea consumption. Among these glycosides, the apigenin-8-C-[alpha-l-rhamnopyranosyl-(1-->2)-O-beta-d-glucopyranoside] was identified for the first time in tea infusions. Depending on the structure, the flavon-3-ol glycosides were found to induce a velvety and mouth-coating sensation at very low threshold concentrations, which were far below those of catechins or theaflavins; for example, the threshold of 0.001 micromol/L found for quercetin-3-O-[alpha-l-rhamnopyranosyl-(1-->6)-O-beta-d-glucopyranoside] is 190000, or 16000 times below the threshold determined for epigallocatechin gallate or theaflavin, respectively. Moreover, structure/activity considerations revealed that, besides the type of flavon-3-ol aglycon, the type and the sequence of the individual monosaccharides in the glycosidic chain are key drivers for astringency perception of flavon-3-ol glycosides.
authors.affiliation: Deutsche Forschungsanstalt für Lebensmittelchemie, Lichtenbergstrasse 4, D-85748 Garching, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Scharbert
authors.forename: Nadine
authors.initials: N
authors.lastname: Holzmann
authors.forename: Thomas
authors.initials: T
authors.lastname: Hofmann
mesh_terms: D044946:Biflavonoids / Q000032:analysis; D002392:Catechin / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D044948:Flavonols / Q000032:analysis; D006027:Glycosides / Q000032:analysis; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D010636:Phenols / Q000032:analysis; D012677:Sensation; D013649:Taste; D013662:Tea / Q000737:chemistry*
chemical_list: D044946:Biflavonoids; D044948:Flavonols; D006027:Glycosides; D010636:Phenols; D013662:Tea; C056068:theaflavin; D002392:Catechin