EVALUATION OF THE EFFECTS OF YEAST-STRAIN AND FERMENTATION CONDITIONSON THE VOLATILE CONCENTRATION PROFILES OF PILOT-PLANT LAGER BEERS

The effect of yeast strain, stirring, pitching rate, fermentation temp erature, aeration, initial wort pH and lagering on the concentration p rofiles of the volatile compounds in the resulting beers were studied. Univeriate and multivariate analyses of variance were applied to inst rumental data to evaluate the differences among samples. Under the con ditions used in these experiences, fermentation temperature, stirring of the wort and lagering gave rise to more changes in the concentratio ns of volatile constituents than pitching rate, yeast or wort reoxygen ation. Main interactions were found to occur between fermentation temp erature and initial pH, between stirring and pitching rate and between stirring and fermentation temperature. The effect of the different fe rmentation variables on specific volatile compounds is also discussed.