Studies On Process Optimization Of Conversion Of Fermentable Sugar Into Ethanol By S.cerevisiae

In the present work, Saccharomyces cerevisiae strains C18,C19,308-3 and Hs27a were used for investigating the application of acid protease, rough complex enzymes which contain protease, xylanohydrolase and β -glucoamylase, and refined complex enzymes which contain xylanohydrolase, β -glucoamylase and cellulase in ethanol fermentation, when the raw materials were complex of 30% corn flour and 70% flour. The effect of three enzymes on the efficiency of conversion fermentable sugars to ethanol by S.cerevisiae was studied. The results were showed as following:1. Rough complex enzymes could accelerate the ethanol fermentation and raise theefficiency of raw materials utilization. The optimal technology condition that the additive amount of rough complex enzymes was 4% of raw materials was got. The suitable time for addition enzymes into medium was after cooking. The medium was kept at 40℃ for 3 hours in water bather, then it was sterilized at 115℃ for 20min.2. The fermentation period might be shortened and the efficiency of conversion of rawmaterials into ethanol might be increased when suitable acid protease was added into the medium. The optimal technique condition that the additive amount of acid protease was 0.01% of raw materials at the beginning of fermentation was got。3. Refined complex enzymes could accelerate the ethanol fermentation and raise the efficiency of raw materials utilization. The suitable additive amount was 0.1% of raw materials at the beginning of fermentation.4. Rough complex enzymes, acid protease and refined complex enzymes could...