Bugging Hop Analysis – on the Isomerization and Oxidation of Terpene Alcohols during Steam Distillation

Abstract

The major monoterpene alcohols of the hop essential oil undergo isomerization and oxidization reactions during steam distillation. Nerol and geraniol predominantly isomerize, their conversion gives rise to linalool and α-terpineol. Linalool is converted into isomeric furan and pyran linalool oxides, 2,6-dimethyl-3,7-octadiene-2,6-diol and 2,6-dimethyloct-7-en-2,6-diol. The chemical conversion of analytical targets during sample clean-up by steam distillation is objectionable and interferes with precise hop oil analysis.