Technical Study Of Dried Yeast Suitable For The Fermentation Of High Sweet Material

Sweet sorghum can grow in the arid area in China, and it is abundant, cheap, sweet sorghum can be used in the production of alcohol through which the safe ,cheap and environment-friendly energy can be obtained and the shortage of energy worldwide can be released. More and more yeast is needed to satisfy the fermentation of sweet sorghum straw to produce alcohol in large scale, but now the research and production of dried yeast powder in China are rarely reported. In this paper, a new yeast strain that performed well in the fermentation of sweet sorghum straw for alcohol production was obtained. The constitution of medium was optimized and the population was enlarged step by step. After the concentration and freezing-dry, the dried yeast powder was obtained.Main research contents were as follows:Firstly,the mutant yeast strains that can produces most alcohol in the basic medium of .sweet sorghum juice were selected and purified. The nitrogen source and different inorganic salt of alcohol fermentation was obtained from the single factor experiment,and the optimal fitting combinations get from the four factors and three level of the orthogonal fitting were: adding 0.3% (NH4)2SO4, 0.1%H3PO4, 0.3%MgSO4, 0.2%CaCl2, 0.03%KH2PO4 in sweet sorghum juice of the sugar degree 12°above. In enlarge culture, the optimal incubation conditions were temperature 28℃,the pH 5.0, the amount of inoculation was 10%, the time of each procedure culture was 24 hours.Secondly, best centrifugation condition with L933orthogonal designing experiment was :4℃, 6000rpm, 30min. A large amount of germ can be acquired, which was suitable for the procedure that follows.Thirdly, The optimal technical method for production of yeast powder obtained from the single factor experiment. This experiment showed that culture enlarged step by step can reach the research object. Dried yeast powder can be obtained through enlarged culture, centrifugation and freeze-drying. The formula of protective agent for vacuum .freeze-drying was glycerin 10g and sucrose 10g. Through track test with every steps in technological method, it was found that the CO2 loses did not change a lot in each step.