Effects of different parameters on ethanol yield of fermentation with immobilized yeast fermentation from sweet sorghum stalk juice

Experiments of ethanol fermentation with immobilized yeast from stalk juice of sweet sorghum were carried out in shaking flasks and a 5L-stirring bioreactor in order to investigate the effects of parameters such as temperature, pH value and particle stuffing rate on ethanol yield. Results from single parameter experiment in the shaking flasks showed that the suitable temperature, pH value and particle stuffing rate were 34℃, 4.5 and 25%, respectively. The verification experiment results in the shaking flasks at the corresponding parameters demonstrated that the ethanol yield and the sugar utilization rate were 95.15% and 88.65%, respectively, when the final fermentation time was 6 h. The verification experiment results in the 5 L-stirring bioreactor showed that the ethanol yield and the sugar utilization rate were 96.72% and 99.86%, respectively, when the final fermentation time was 10 h. The research has provided a useful reference for refining ethanol from sweet sorghum.