| Due to the total sugar concentration of sugar cane juice was low(about 120g·L-1),the alcohol production of sugarcane juice alcohol fermentation?v/v?was only7%-8%.The main topics of this thesis are as follows,in order to obtain the higher ethanol concentration,we added the cassava flour into the sugar cane juice,the total sugar was improved?relative to pure sugarcane juice?,The results as follows:1.Differences of glucose and fructose utilization in ethanol fermentation by mixed yeast strains.To provide basic information for sugarcane and cassava fermentation,the inoculation proportion of S.cerevisiae GJ2008 and GGSF16 was to evaluate its impact on glucose and fructose fermentation.The same concentration of glucose and fructose medium?the total concentration is about 220 g/L?to carry out ethanol fermentation by the mixed strains of S.cerevisiae GJ2008 and GGSF16 at the different radios?10:0?9:1?8:2?7:3?6:4?5:5?4:6?3:7?2:8?1:9?0:10?,the change of each parameter along the fermentation process was determined.The results showed that S.cerevisiae typically utilization glucose and fructose with different efficiency:the glucose transfer is faster than fructose,as the number of S.cerevisiae GGSF16 goes up,the metabolism rate of glucose becomes more faster;in addition,during the fermentation,the utilization of fructose is inhibited to a larger extent than glucose by the ratio of S.cerevisiae GJ2008 and GGSF16.And the impact on ethanol production has been small by radios of S.cerevisiae GJ2008 and GGSF16.In contrast,the highest efficiency of total and consumption sugar fermentation is 0:10.Therefore,the Saccharomyces cerevisiae GGSF16 will be used as the experimental strain in this study.2.Mixed the sugarcane juice and cassava with different ratios?L:kg,15:1?9:1?6:1?4:1?,added and the liquefied enzyme and heat by water barth at 85?for one hour.Glucoamylase??-1,4-glucose hydrolase?was added in an amount of 150 U/g of tapioca flour,and the sterilized urea was added to the fermentation medium with different initial total sugar concentration at 6 g/L,p H 4.5,32?,120 r/min for alcohol fermentation,the pure sugar juice?total sugar concentration 120 g/L?was used as the control group.The results showed that when the initial total sugar concentration was149.6 g·L-1?180.1 g·L-1?211.3 g·L-1?241.8 g·L-1,the fermentation alcohol was 8.03%?v/v??9.82%?v/v??11.60%?v/v??12.04%?v/v?,compared with the control group,the fermentation ethanol were improved 8.37%,32.52%,56.55%and 62.48%respectively.In addition,when the initial total sugar concentration was 149.6 g·L-1?180.1 g·L-1?211.3 g·L-1?241.8 g·L-1,and the final total sugar concentration was 14.00g·L-1?18.33 g·L-1?22.12 g·L-1?48.71 g·L-1,the fermentation cycles were 24 h?30h?36 h?42 h?That the initial total sugar concentration is high,at the end of fermentation,residual sugar concentration is higher,the fermentation period is longer,the initial total sugar concentration is low,at the end of fermentation,residual sugar concentration is low,the fermentation period is short.3.Mixed the sugarcane juice and cassava with different ratios?L:kg,15:1?9:1?6:1?4:1?,added and the liquefied enzyme and heat by water barth at 85?for one hour,the filtrate was filtered by filtration to obtain a filtrate.Glucoamylase??-1,4-glucose hydrolase?was added in an amount of 150 U/g of tapioca flour,and the sterilized urea was added to the fermentation medium with different initial total sugar concentration at 6 g/L,p H 4.5,32?,120 r/min for alcohol fermentation,the pure sugar juice?total sugar concentration 120 g/L?was used as the control group.The results showed that the mixed liquefaction filtrate of sugarcane juice and cassava flour?L:kg,15:1,9:1,6:1,4:1?was subjected to alcohol fermentation.The fermentation period respectively was 24h?30h?36h?42h,the fermentation efficiency of total sugar respectively was 84.50%?84.94%?87.50%and 78.16%,the fermentation efficiency of sugar consumption was 91.48%?94.94%?96.67%?98.73%,and the final fermentation ethanol?v/v?respectively was 8.23%?9.87%?11.90%and 12.20%.The fermentation cycles were as same as those of the mixed liquefied liquid alcohol fermentation test at the same ratio?L:kg,15:1?9:1?6:1?4:1?,but the fermentation efficiency was improved 1.87%,0.34%,2.59%and 1.27%respectively,the improvement is not obvious.Considering the parameters of the fermentation,the sugar cane juice and the cassava flour were mixed with liquefaction at 6:1?L:kg?alcohol fermentation.The fermentation efficiency was higher,which could further improve the production efficiency and equipment utilization rate.4.Be based on the sugarcane juice and cassava mixed alcohol fermentation experiment.The optimum mixing ratio of sugar cane juice and cassava flour was determined by considering various parameters?residual sugar content?alcohol?cycle?fermentation efficiency and so on?,the optimum mixing ratio?L:kg?of sugarcane juice and cassava flour was determined to be 6:1,the mixture was liquefied to remove alcohol and fermented by Braun5L fermentor.The results showed that the total sugar content was 210.3 g·L-1,and the liquefied filtrate was mixed with tapioca powder.At the stirring speed of 200 rpm,natural p H?32?and microaeration of 80 m L/min.The fermentation alcohol was 11.6%?v/v?,the residual sugar was 21.00 g·L-1,the fermentation period was 42 h,the fermentation efficiency of total sugar was 83.69%,the fermentation efficiency of sugar consumption was 92.98%. |
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