Inhibition of Beer Volatiles Formation by Carbon Dioxide Pressure. James F. Rice, Etzer Chicoye, J. Raymond Helbert, Miller Brewing Company, Milwaukee, Wis., and John Garver, University of Wisconsin, Madison, Wis.. J. Am. Soc. Brew. Chem. 35:0035, 1977.

The formation of total volatiles and yeast growth were inversely related to the CO₂ counterpressure applied during 100-liter fermentations. However, the rate of fermentation was relatively unaffected. Thus, 8 psig (22.7 psia) CO₂ counterpressure in a 22°C fermentation repressed both total yeast growth and total volatiles concentration to the levels present in a 15°C fermentation with 0 psig (14.7 psia) CO₂ counterpressure. The repression of individual volatile compounds, however, was not uniform. The influence of temperature, agitation, and CO₂ counterpressure upon the dissolved CO₂ concentration during active fermentation was quantified. It was shown that the degree of supersaturation (termed the supersaturation coefficient), which is the ratio of the dissolved CO₂ concentration during active fermentation to the CO₂ saturation level, was constant over the ranges of temperature and CO₂ counterpressure examined, at constant agitation. The supersaturation coefficient varied inversely and in a linear manner with agitation. At sufficiently high agitation, no CO₂ supersaturation existed during active fermentation, thus the supersaturation coefficient was 1.0.

Keywords: Agitation, Fermentation, Temperature, Yeast growth.