Research On Kinetic Model For Ethanol Simultaneous Saccharification And Fermentation

Alcohol, which used for the raw materials of food, medicine and chemical industry, playsan important role in the national economy. Since two oil crisis happened in1970s, alcohol hasreceived a lot of attention as a new kind of bio-energy. Simultaneous saccharification andfermentation combines the mashing process with fermentation process. Compared with thetraditional fermentation processes, simultaneous saccharification and fermentation shortensworkshop section, reduces the overall fermentation time, thus not only lower the energydepletion, but also heighten the productivity of alcohol greatly. The research of alcoholsimultaneous saccharification and fermentation kinetics helps increase understanding aboutsimultaneous saccharification and fermentation process for people, and provides a theoreticalbasis for the amplification of the industrial and production optimization of operatingconditions. Although there have been many researches on the enzymolysis kinetics ofglucoamylase and alcohol fermentation kinetics, the research for the kinetics ofsaccharification and fermentation at the same time has not been reported yet. This paperestablish a model of alcohol simultaneous saccharification and fermentation reducing sugarsconsumption kinetics, according to the rules of cell growth, ethanol generation and substrateconsumption in the process of alcohol simultaneous saccharification and fermentationexperiment.In this paper, the phenomenon of the inhibition of product and the inactivation of enzymeswas studied. Under the condition of simultaneous saccharification and fermentation(40℃、pH4.5), The Michaelis constant and product inhibition constant were identified respectively as1.489and0.2mg·mL-1by experiment in the reaction of glucoamylase enzymatic. The modelof alcohol simultaneous saccharification and fermentation reducing sugars consumptionkinetics was deduced from the enzymatic hydrolysis reaction equation.The relationship of the cell growth, ethanol generation and substrate consumption in theprocess of alcohol simultaneous saccharification and fermentation with the time and thecharacteristics were analyzed. The effect of the content of DO, pH and temperature on thealcohol generating process in the fermentation process of alcohol and the effect of the ratio ofmaterial to water on alcohol yield were discussed.The reference of the specific growth rate in the Logistic Model was redefined. The original reference cell concentration term was defined as alcohol content term to get the modifiedLogistic Model. The modified Logistic Model was used fitting the simultaneoussaccharification and fermentation experimental data when the initial ratio of material to waterwas1:4、1:3.5、1:3、1:2.5.The results of theoretical maximum alcohol concentration was68.875~87.79g/L，mostly identical to the maximum alcohol concentration from experimentswith error less than7%.Several ways, such as linear fitting experimental data, classic formula parameterscalculation and matlab fitting calculation were ultimately used to solve the model parametersof alcohol simultaneous saccharification and fermentation reducing sugars consumptionkinetics, and then the experiment data was used to validate the model. From the results ofprediction results, reducing sugars consumption kinetics model fits well on the experimentdata.