Growth and fermentation factors for different brewery yeasts

Abstract

In this investigation, an attempt has been made to study growth and fermentation of brewery yeasts, as far as possible, in solutions of known composition. Growth and fermentation were first studied separately at a temperature of 30°C and with conditions adjusted as to emphasize first growth under one set of conditions and then alcoholic fermentation under another. Finally, the combined process as it occurs in brewery fermentation was studied at lower temperatures, also using solutions of known composition. In the growth studies, it was found that lager yeasts of different strains showed marked differences in their growth requirements. These growth requirements were found to be relatively stable and could be used to identify certain specific strains of yeast. In the fermentation studies, yeast nutrients were combined to produce a medium in which the fermentation rate was equal to that obtainable with beer wort. In the third phase of the work, this medium was employed under conditions of brewery fermentation such that both growth and fermentation occured and, in this instance, it was found that inositol played a very important role in determining the rate of attenuation. The significance of this finding was further investigated with different brewery yeasts.