Effects of Different pH on the Ethanol Production by Immobilized Saccharomyces Cerevisiae in Sweet Sorghum Stem Juice

The juice of sweet sorghum stem of soluble sugar content 113g/L was used as experimental material; ethanol fermentation experiments were conducted in a shaking flask and the bath shake bed to investigate effect of temperature on the ethanol fermentation of sweet sorghum stalk juice by immobilized yeast. Test pH values were selected 3.5, 4, 4.5, 5 and 5.5 five gradient, The experimental results in the shaking flask showed that the pH 4. 5 are the most suitable condition to the ethanol fermentation of sweet sorghum stalk juice by immobilized yeast. Under this condition, it can be obtained the better ethanol yield,CO2 weight loss rate and the lower residual sugar content.