Kinetic Models and Effects of Initial Total Soluble Sugar Concentrations on Batch Ethanol Fermentation of Sweet Sorghum Stalk Juice by Saccharomyces cerevisiae Strain

Abstract

Effects of initial total soluble sugar concentrations on batch ethanol fermentation of sweet sorghum stalk juice by Saccharomyces cerevisiae strain were investigated at initial total soluble sugar concentrations of 85–156 g/L. The result showed that cell growth and the ethanol yield were increased with the increase of initial total soluble sugar concentrations. The kinetic parameters at initial total soluble sugar concentrations of 85–156 g/L were obtained. With the increase of initial total soluble sugar concentration, an inhibition of initial total soluble sugar concentration on the maximum specific growth rate (μmax) was observed. However, the increase of initial total soluble sugar concentration favors in the increase of the maximum specific ethanol production rate (qmax). The models proposed by Hinshelwood were found to be appropriate for describing the batch growth and ethanol fermentation of sweet sorghum stalk juice by immobilized Saccharomyces cerevisiae at initial total soluble sugar concentrations of 85–156 g/L because the correlation coefficients for the cell growth kinetic model and the ethanol production kinetic model were greater than 0.99.