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Growth characteristics of bakers' yeast in ethanol

Authors

  • Kowda M. Wasungu,

    1. Centre de recherche en nutrition and Département de sciences et technologie des aliments, Université Laval, Ste-Foy, Québec G1K 7P4, Canada
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  • Ronald E. Simard

    1. Centre de recherche en nutrition and Département de sciences et technologie des aliments, Université Laval, Ste-Foy, Québec G1K 7P4, Canada
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Abstract

The influence of temperature (15° −40°C) and pH (2.5–6.0) on the continuous growth of bakers' yeast (Saccharomyces cerevisiae) at steady state in 1% ethanol was investigated. Optimal temperature and pH were 30°C and 4.5, respectively. The short-term effect of ethanol concentration (0.1–10.0%) on the yeast growth was assessed in batch culture. Up to 1% of ethanol, the yeast growth increased in function of the ethanol concentration in the medium. The biomass reached a maximum within the interval of 1–4% of ethanol (7.9 and 31.6 g/L, respectively) and decreased at higher concentrations. The residual ethanol concentration in the medium increased rapidly when the initial ethanol concentration exceeded 4%. The best-fit model obtained for growth inhibition as a function of ethanol concentrations was that of Tseng and Wayman: μmS/)K + S( − i (SSθ). With this model, the specific growth rate (μ) decreased linearly as the ethanol concentration increased between the threshold value (Sθ) of 11.26 g/L to be fully inhibited at 70.00 g/L (S;) an inhibition constant (i) of 0.0048 g L−1 h−1, a maximum specific growth rate (μm) of 0.284 h−1, and a saturation constant (K) of 0.611 g/L were obtained.

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