THE EFFECT OF YEAST TREHALOSE CONTENT AT PITCHING ON FERMENTATION PERFORMANCE DURING BREWING FERMENTATIONS

The effect of yeast trehalose content al: pitching on the fermentation performance during brewing fermentations was studied using a commerci al strain of lager yeast, Saccharomyces cerevisiae (AJL 2155). Pitchin g yeasts with different trehalose contents were obtained by collecting cells in suspension after 96 h and 144 h of fermentation in EBC tubes in 10.8 degrees P brewers wort at 14 degrees C. The trehalose content of the pitching yeast had no effect on growth, specific gravity and e thanol production during the subsequent fermentation. A high trehalose content of the pitching yeast. however, sustained cell viability duri ng the initial !stage of fermentation, increased the carbohydrate util isation rate and increased the production of isoamyl alcohol and isobu tanol. For these aspects of fermentation performance, the trehalose co ntent of the pitching yeast may prove useful in evaluating the vitalit y of pitching yeasts within the brewery.