STRAIN-SPECIFIC RESPONSE OF BREWERS-YEAST STRAINS TO ZINC CONCENTRATIONS IN CONVENTIONAL AND HIGH GRAVITY WORTS

The effect of zinc on a variety of yeast strains is extensively docume nted in the literature. However, due to the varied experimental protoc ols employed in each study there is little opportunity to directly com pare the strain specificity of this ion. In the present study, the res ponse of six yeast strains (three Saccharomyces cerevisiae tale type) and three S.cerevisiae (lager type)) to altered zinc concentrations, i n both high (1080 OG) and conventional (1048 OG) gravity worts, was in vestigated. Varying the initial wort zinc concentration in both gravit ies had an effect on the ethanol production, rate of fermentation, cel l number and sugar uptake of all six strains studied. The extent of th e response was found to be dependent upon the zinc concentration, the strain employed and wort gravity employed.