Volatilization of Aroma Compounds Relevant for Wheat Beer in Water Under Conditions Simulating Alcoholic Fermentation

J. Am. Soc. Brew. Chem. 69(4):187-190, 2011 The subject of this study was the volatilization behavior of three of the most important aroma compounds found in wheat beer. The results revealed how likely these compounds are to be liberated through the scrubbing action of CO(2) during fermentation. For this reason, we were interested in determining the factors that influence volatilization and result in the liberation of these compounds by CO(2). In the trials performed, the behavior of isoamyl acetate, ethyl acetate, and 4-vinylguaiacol was tested in water with controlled injection of CO(2). To mimic the formation of CO(2) during normal fermentation (in won with an original gravity of 12 degrees P), a system was designed and constructed specifically for this study. The flavor compounds were analyzed using GC and HPLC, and the variables temperature, pH, and alcohol content were tested under simulated fermentation conditions. Isoamyl acetate exhibited the highest volatility, followed by ethyl acetate. In contrast, 4-vinylguaiacol was the most difficult compound to liberate. As the temperature rose, the volatility of the aroma compounds generally increased; pH, however, had no effect on volatilization behavior. An alcohol content of up to 4% by volume did not affect the volatility of the compounds tested in this study. Acetate esters were more readily liberated than the phenolic compound 4-vinylguaiacol.