Yeast Strains and Hop Varieties Synergy on Beer Volatile Compounds

The volatile compounds produced in beers are complex and influenced by numerous factors like barley, brewing and fermentation process, hop variety and yeast strain. In this study, hop variety and yeast strain have been chosen to evaluate their influences on the volatile compound profile in beer. Malt wort was hopped with 4 different varieties of French aromatic hops and fermented with 3 different yeast strains. Volatile compounds were analysed by Stir Bar Sorptive Extraction-Gas-Chromatography (SBSE-GC-MS). Statistical analysis (ANOVA) were performed to test the influence of yeast strain and hop variety on the concentration of each of the measured compounds. Among the 39 volatile compounds detected, 9 of them were influenced only by hop variety, 2 by yeast only and the 28 remaining by both hop and yeast together. As expected, terpenes concentration in beer is directly linked to the choice of hop variety used, but it appears the yeast strains can also influence that parameter. Surprisingly, hops variety influenced the final concentration of esters, highlighting that an interaction between hops compounds and yeast metabolism remains to be investigated.