The industrial distillery yeast Saccharomyces cerevisiae was determined for its capacity to ferment monosaccharide lactose derivatives. Analyses were carried out to examine their natural predisposition for fermentation of media with lactose hydrolysates (12%) and in addition, the rate of saccharides utilization in the experimental fermentation medium (6% glu/6% gal) was monitored as affected by the method of preliminary propagation of yeast: on standard medium with glucose or on adaptive media with galactose or mannose. It was demonstrated that the level of lactose derivatives attenuation by the yeast examined did not exceed 4% v:v alcohol. A chromatographic analysis of the saccharides enabled determining the rate of their utilization in the fermenting mixture. The effect of delayed utilization of galactose by the yeast was found to be evoked by the phenomenon of glucose repression. The preliminary propagations of the analyzed yeast on adaptive media before the fermentation process caused the acceleration of galactose assimilation, resulting in increased alcohol content in fermented media to 4.2-4.4% v:v.

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