Brief Insight into the Underestimated Role of Hop Amylases on Beer Aroma Profiles

Abstract

The current trend in craft breweries is to carry out heavy dry-hopping by increasing the hopping rate. This practice sometimes leads to uncontrolled and aberrant aroma profile production. The aim of this work was to determine whether part of the enzymatic content of hop (α-amylase and β-amylase) could impact yeast metabolism, resulting in aroma profile modification during secondary fermentation. In this research, spectrophotometric methods were used to assess the amylase activity within hop. Moreover, liquid chromatographic methods (HPLC-ELSD) showed modification of the beer sugar profile by production of glucose and maltose as well as by the degradation of a higher degree of polymerization sugar by hop enzymes. Furthermore, gas chromatographic techniques (GC-ECD/FID) were used to assess yeast metabolism using vicinal diketones (diacetyl/pentanedione) as a marker of the secondary fermentation. Finally, a principal component analysis (PCA) of the yeast main aromas (esters, higher alcohols, and aldehydes) demonstrated the significance of this yeast-hop interaction on the beer’s aroma profile.