Abstract :
[en] 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.
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