Fate of 2-sulphanylethyl acetate and 3-sulphanylpropyl acetate through beer aging

Abstract

Sulphanylalkyl alcohols and their corresponding acetates were investigated in 14 commercial Belgian beers. Although it was the major peak at the pulsed-flame photometric detector, the empyreumatic 2-sulphanylethyl acetate was found at concentrations below its individual odour threshold, estimated at 40 µg/L (0–4 µg/L in most fresh beers, 5–12 µg/L in three fresh high-bitter beers). Both the Ehrlich pathway and hop constituents contribute to this content. In 11 of the investigated samples, synthesis of 2SE-A and 3-sulphanylpropyl acetate (roasted, burned) continued during the first three months of storage. Although below their individual thresholds, these compounds might interact by synergy with other aged flavours. As yeast was absent from most of the investigated bottles, chemical degradation of precursors is suspected. Copyright © 2012 The Institute of Brewing & Distilling