STUDIES ON NON-BIOLOGICAL HAZES OF BEERS*

Abstract

Malt polyphenols have been extracted from whole crude husk preparations (containing, however, pericarp) and then fractionated by precipitation with lead acetate followed by chromatography on cellulose whereupon several components are obtained in chromatographically homogeneous form. Of these the main components are (a) leucoanthocyanins, which on heating with mineral acid give respectively delphinldin and cyanldin, and (b) d(+)-catechin. Attention is drawn to the fact that the leucoanthocyanins of hops and malt differ in nature. In addition to (a) and (b), further phenolic compounds, including vantllic acid, ferulic acid, p-coumaric acid, and a number of as yet unidentified substances, have been isolated; these also occur together with gallic acid among the products of the degradation of the total tannins with alkali. The above findings are discussed in relation to the haze problem in brewing.