Evaluation of kinetic parameters and thermodynamic quantities of starch hydrolysate alcohol fermentation by Saccharomyces cerevisiae

The kinetic parameters and thermodynamic quantities of corn starch hydrolysate fermentation by Saccharomyces cerevisiae are evaluated following two different approaches and using the experimental data of batch fermentations carried out at different temperatures. The former approach, that is based on the Arrhenius equation, allows for the separate calculations of thermodynamic quantities referred to the transition states of both alcohol fermentation and thermal deactivation. The latter, supposing the existence of an instantaneous equilibrium between active and inactive forms of the biocatalyst, includes all these quantities in the same relationship. The results obtained in this study suggest that the simple activated-complex theory is inadequate to the kinetic and thermodynamic description of a process using microorganisms, while the so-called ''thermodynamic approach'' can represent a promising alternative.