THE USE OF14C-LABELLED POLYPHENOLS TO STUDY HAZE FORMATION IN BEER

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Abstract
Haze formation in beer is claimed to involve the gradual polymerization of polyphenols and their subsequent reaction with proteins to form insoluble complexes. The mechanism of haze formation has now been studied using 14C-labelled epicatechin and dimeric catechin. Epicatechin does not polymerize to form dimeric or trimeric polyphenols when beer is stored and is only incorporated into beer haze to a small extent. Some of the epicatechin combines with nitrogen-containing compounds during storage to form soluble complexes. However, dimeric catechin does not form soluble complexes with nitrogen-containing compounds and instead there is a substantial incorporation of this dimer into beer haze. Dimeric polyphenols are important haze precursors which form insoluble complexes with one or more of the polypeptides of beer, probably by an oxidative coupling mechanism.