Study On Kinetic Of Ethanol Simultaneous Saccharification And Fermentation By Raw Cornstarch

Fermented alcohol as a new type of green renewable materials occupies an importantposition in the food, chemical, pharmaceutical and many other areas. Fermentation kineticmodels could be used to describe relationship among the principal state variables and toexplain the behavior of fermentation quantitatively, in addition, it can also provide theoreticalbasis for the analysis, design, optimization and operation of the fermentation process. Thealcohol production from raw cornstarch is a process that usually consists of two phases:amylases hydrolysis of cornstarch to glucose and glucose fermentation to ethanol by yeasts;Simultaneous saccharification and fermentation of the raw cornstarch is a new fermentationtechnology that raw material without cooking and liquefaction progress, directly carried out inthe fermentation tank for saccharification and fermentation simultaneously. Compared withthe traditional fermentation process, it is characterized with simple process, savingfermentation time, reducing the equipment investment and energy consumption andeliminating the inhibitory effect of high concentration of sugar. The kinetics of the enzymatichydrolysis process and the fermentation process were studied in the article separately.For the enzymatic hydrolysis process, the influence of the concentration of product,substrate and enzyme deactivation on the rate of enzymatic hydrolysis process were studied.Product inhibition point and its value (6.95g/L) were determined by the enzymatic hydrolysisexperiments, and then established the kinetics model which contains product inhibition,inhibition point and enzyme inactivation, the model parameter Km, Vm, KGand a wereidentified as14.51g/L,0.8429g/(L·min),0.0080g/L and20.6831respectively, the correlationcoefficient R2is0.9939.For the fermentation process, the relationship between the accumulation or consumptionof the fermentation product, cell growth, total sugar, reducing sugar and the change of timewere analyzed as well as their characteristics; For the model parameters in kinetic model ofalcohol, the influence of different solving methods on the result was also discussed. Here isthe idea: describe the generation process of the product alcohol through the idea and methodof chemical engineering and inspired by classical fermentation kinetics, the established modelwas used to simulate the fermentation experiments with the initial ratio of water to materialwere1.5,2.5,3.5and4.5. The theoretical maximum alcohol concentration forecasted by the model was52.7~66.4g/L, which mostly close to the experimental value, the correlationcoefficients R2were0.9941,0.9731,0.9464and0.9635respectively.For the substrate consumption process, based on the assumption that growth-associatedbetween biomass and the products we established the substrate total sugar consumptionkinetic model, and simulated the experimental data of the ratio of water to material was1.5~4.5, the correlation coefficients R2were0.9363,0.9446,0.9413and0.9501respectively.Through the experimental validation and the correlation coefficient show that the theoreticaldata derived from established model agree well with the experimental data.