Study On Application Of Compound Enzyme Preparation In The Production Of Fuel Ethanol With Mixed Raw Materials

With the expansion of the promotion scope of biofuel ethanol for vehicles in China,the fuel ethanol industry is bound to usher in a period of rapid development.The production of fuel ethanol from mixed starchy raw materials can diversify the raw materials,it can also effectively solve aging grain and "problem" grain.Adding enzymes in the production of fuel ethanol is helpful for efficient utilization of raw materials and high concentration ethanol fermentation.According to the characteristics of different enzymes and raw materials,acidic protease,xylanase,pullulanase,cellulase,beta-glucanase,pectinase and phytase were selected to study.The main conclusions of this paper are as follows:The effects of different enzymes on the same raw material are significantly different,and the effects of the same enzymes on different raw materials are also different.Acidic protease and pullulanase could significantly promote ethanol fermentation of maize,cassava and wheat.In compared with the control group,adding acid protease,the alcoholicity of mash at the end of fermentation increased by 5.82%,3.00% and 6.79%,and when adding pullulanase,the alcoholicity increased by 3.64%,4.12% and 3.77%.Xylanase can promote alcohol fermentation of maize and wheat significantly,and cassava alcohol fermentation can be promoted to a certain extent.In compared with the control group,the alcoholicity of adding xylanase increased by3.85%,4.75% and 1.03%.Cellulase and phytase can promote alcohol fermentation of maize,cassava and wheat.When cellulase was added,compared with the control,the alcoholicity increased by 2.76%,1.86% and 2.26%,and the alcoholicity increased by2.47%,1.58% and 1.36% when phytase was added.In compared with the control group,pectinase and beta-glucanase had no obvious effect on ethanol fermentation of three raw materials.Through single factor experiment and orthogonal experiment,the optimum combination of compound enzyme preparation in ethanol fermentation with mixed rawmaterials(flour: corn flour: cassava flour = 5:3:2)was acid protease 12U/g raw material,xylanase 150 U/g raw material,pullulanase 20 U/g raw material,phytase 12 U/g raw material and cellulase 16 U/g raw material.When the compound enzyme preparation was added during inoculation,the alcoholicity reached 15.10%(v/v)at the end of fermentation,compared with the control group,which increased by 9.90%.Compound enzyme preparation is suitable for inoculation.It can increase the yeast concentration in fermentation broth,promote yeast growth,increase the concentration of mixture,increase the fermentation speed and shorten the fermentation period by 12 hours.The single factor experiment and orthogonal design were carried out to optimize the fermentation conditions of high concentration ethanol,which from mixed raw materials by adding complex enzyme preparation during inoculation.The results showed that the optimum fermentation conditions of high concentration alcohol with mixed raw materials were: fermentation temperature 33 ?,initial pH value 4.5,fermentation time 56 h,inoculation volume 25%,shaking speed 140 r/min.Under these conditions,the alcoholicity of fermented mash could reach 15.95%(v/v),which was higher than that in control by 10.38%.