Synchronization of isothermal calorimetry and liquid cultivation identifying the beneficial conditions for producing ethanol by yeast Saccharomyces cerevisiae fermentation

This study focused on the Saccharomyces cerevisiae ( S. cerevisiae ) fermentation process using various sugar concentrations for ethanol fermentation; the isothermal calorimeter (TAM Air) and liquid state fermentation were compared to determine the effects of adjusting the sugar concentration, culture temperature, and culture time for S. cerevisiae cultivation. We compared the effects of different culture temperatures, 25, 31, and 37 °C, various glucose and fructose concentrations, 2, 4, and 8%, and suitable culture times, up to 96 h, for S. cerevisiae growth and metabolism under synchronous conditions. Comparisons of the calorimetric measurement and liquid state fermentation results were made to determine the beneficial culture conditions at 25 °C. In addition, based on the heat power-time curves of the TAM Air tests, we obtained an accessible kinetics model by autocatalytic reaction simulation, which further determined an accurate culture time of 85.22 h, a high ethanol production of 34.80 μL mL −1 in medium with 8% fructose; the time to reach the maximum growth rate under an isothermal temperature of 26.59 °C for all media was 24 h, and a longer growth lifetime of 134. 03 days was achieved in 8% fructose at 4 °C. Overall, the results of this research can be widely used in beverages, bioenergy, and food processing.