Screening Of Yeast Strains With High Alcohol Yield In The Fermentational Sweet Sorghum Juice

Sweet sorghum is also known as sugar sorghum. Because of its rich stem juice and its high sugar content, sweet sorghum is a good bio-energy resource. We analyzed the nutritional content of its stalk and found that sweet sorghum juice containing all major nutrients for yeast growth and fermentation, so it can completely meet the requirements of alcohol yeast to growth and development. so sweet sorghum juice is more appropriate as a raw materials to producing fuel ethanol.In fermentation industry, select high-quality and high-yield strains of micro-organisms is the basis and key job. We use natural breeding methods, isolated yeast strains from nature suitable for fermentation of sweet sorghum juice, as the raw material prepared by high alcohol fuel ethanol yeast. And 165 strains of yeast are isolated from different matrix and sources.Through preliminary screening,the second screening and alcohol fermentation tests, ultimately obtain five yeast strains which can be produce high alcohol fermentation and suitabled sweet sorghum as raw material,We test these five strains of alcohol fermentation through single-factor test and the four factors and three level orthogonal. The yeast strains tested the combination of the best fermentation conditions:yeast G中2-5:its suitable fermentation temperature is 34℃,its suitable fermentation is pH=5.1.,its suitable fermentation inoculum is 6.5% and juice brix of sugar is 19Brix. Yeast G中3-2:appropriate fermentation temperature is 33℃; suitable fermentation pH value of 5.1; suitable fermentation inoculum is 6.5%; juice sugar brix isl9Brix. The yeast G后-3:suitable fermentation temperature is 32℃, suitable fermentation is pH=5.1,suitable fermentation inoculum is 4.5%,and its juice brix of sugar is 19Brix. The yeast S中1-1:appropriate fermentation temperature is 36℃, suitable fermentation pH value is 5.1; suitable fermentation inoculum is 6.0% and its juice brix is 19Brix. The yeast strain S. 4-1:suitable fermentation temperature is 33℃, suitable fermentation is pH=5.1, its suitable fermentation inoculum is 6.5%, and appropriate juice brix is 19Brix.According to five yeast fermentation in their best conditions of fermentation data, we found that strain G 3-2 is the best final yeast in these five tested yeast strains. To filter out as the ultimate high alcohol yeast, and commercial yeast control experiments carried out Dan Polly. Come to the conclusion:in the 3-2 choice with commercial yeast strains G Dan Polly control, the choice of strains and control strains the same amount of distilled alcohol; the choice of residual sugar after fermentation strains of residual sugar than the control slightly higher volume; optional peak strain than in the control of fermentation strains delayed nearly 8h, slightly extending the fermentation time; optional inoculum strains than the control yeast Dan Polly higher.The paper also studied the final yeast strain G+2-5 on some growth, fermentation characteristics.And the result is:its optimum temperature is 28℃, its suitable fermentation temperature iss 32℃and its suitable fermentation is pH=5.1, suitable fermentation inoculation is 6.0%; appropriate brix sugar juice as 19Brix, its fermentation peaked at 24- 32h; It can ferment use of glucose, maltose and sucrose, but can not use lactose and starch to fermentation.