Cardinal Temperatures for Growth of Osmotolerant Yeasts in Broths at Different Water Activity Values

Abstract

All three cardinal temperatures (Tmin, Topt and Tmax) for growth of 6 strains as well as Tmin and Tmax for growth of an additional 23 strains were determined in solutions of 10, 30, 50 and 60% (w/w) glucose at aw (20°C) of 0.990, 0.970, 0.922 and 0.868, respectively. The Topt for growth of Zygosaccharomyces rouxii and Z. bisporus were 24–28.5°C at aw >0.990 and 31–33°C at aw in the range of 0.922–0.868. Z. bailii showed Topt for growth of 29–31°C and 33–35°C at aw >0.990 and aw <0.922, respectively. The Topt for growth of Torulaspora delbrueckii was 27–28.5°C at aw <0.990 and 31–33.5 at aw in the range of 0.922–0.868. Debaryomyces hansenii showed a Topt of 24°C and 27–29.5°C at aw >0.990 and aw <0.922, respectively. The Tmin and Tmax for growth were also shifted toward higher values as the aw decreased; at aw<0.922 none of the tested strains grew at 4°C within 30 d. Several strains could grow at 42°C only in the presence of high sugar concentrations.