GUSHING PROMOTERS AND SUPPRESSANTS IN BEER AND HOPS

Abstract

The fatty acids present in beer and hops were found to have pronounced effects on gushing, some at concentrations of I ppm or less. Saturated fatty acids are weak gushing promoters, while unsaturated acids are powerful suppressants. A parallel structure-activity correlation also exists in a series of α-acid derivatives and their analogues. Compounds with the unsaturated side-chains intact showed either weak suppressant activity or none at all. Loss of carbon-carbon unsaturation through hydrogenation or cyclization produced powerful gushing promoters, but reduction of carbonyl unsaturation as in ρ-isohumulones, or loss of side chains as in humulinic acids had no effect on gushing. Promoter and suppressant effects of the compounds tested were non-specific and mixtures of unsaturated fatty acids suppressed all instances of gushing, whether natural or artificially induced. The results indicate that beer normally contains both gushing promoters and suppressants, and gushing may sometimes be due to an imbalance between them.