Phenolic Constituents of Beer and Brewing Materials

Beer components removed by treatment with small quantities of Nylon 66 or Polyclar A.T. are composed of small amounts of large numbers of simple phenols and polyphenols derived from malt and hops together with a relatively large quantity of polymerized polyphenolic material associated with protein. Quercetin, kaempferol, isoquercitrin, rutin, (+)-catechin and (+)-epicatechin were identified paper chromatographically as were chlorogenic, neochlorogenic, p-hydroxybenzoic, vanillic, syringic, p-coumaric and ferulic acids. Glycosides and esters of p-hydroxybenzoic, protocatechuic, vanillic, syringic, caffeic, ferulic, sinapic and gentisic acids also occur in beer-polyamide absorbates. Nylon and A.T. remove what appear to be the same simple polyphenols from beer. Aggregates of protein with polymerized polyphenols show marked resemblances to hazes and probably represent precursors very close to beer turbidities. The aggregates, which contain methoxylated phenolic units in addition to anthocyanogen residues, are present in dialysable and non-dialysable forms.