PHENOLIC CONSTITUENTS OF BEER AND BREWING MATERIALS III. SIMPLE ANTHOCYANOGENS FROM BEER

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Abstract
By use of chromatography on a dextran gel, (+)-catechin and six simple anthocyanogens have been isolated from polyamide-beer adsorbates. Three of the anthocyanogens have been obtained in a homogeneous condition whilst two others appear to be mixtures of at least two compounds; a sixth, which is derived by dehydration between two others, was obtained contaminated by minute traces of these. Chromatographic and structural studies indicate that one anthocyanogen is probably a stereo-isomeric form of 5:7:3′:4′-tetrahydroxyflavan-3:4-diol possessing the epicatechin configuration at C2 and C3, another is a biflavan derived by dehydration between (+)-catechin and the flavandiol, and a third appears to be a triflavan derived from one molecule of the flavandiol and one of the biflavan. A further biflavan was isolated which yields delphinidin and (+)-catechin separately under appropriate acidic conditions. The remaining anthocyanogens are mixtures and contain, in addition to (+)-catechin-derived compounds, components which yield (+)-epicatechin with acid. Re-examination of the relevant adsorbates from beer indicates that Polycar removes, proportionally, more (+)-catechin and (+)-epicatechin from beer than does Nylon. A possible relationship between anthocyanogen structure and beer stability is discussed.

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