Product kinetics of Logistic model to simulate ethanol fermentation.

Ethanol plays an important role in the national economy, and is widely used in the raw materials of food, medicine, and the chemical industry. In recent years, with the challenge facing the world's energy security, more and more attention has been devoted to the conversion of biomass into fuel ethanol. Ethanol is considered to be a renewable and clean fuel, which can be an alternative to fossil fuels. So far, compared with other ethanol production methods, the fermentation method to produce ethanol has so many advantages, such as green environmental protection and low cost, that attracts lots of researchers' attention. There are many influence factors in the fermentation process, which make the fermentation process so complicated that it is hard to be controlled. The variation of the ethanol concentration with different fermentation times is directly related to the fermentation results. How to get higher ethanol concentration by a fermentation method has become the hot and difficult issue of the fermentation field. The research of ethanol fermentation kinetic is beneficial for understanding the fermentation process. It provides a theoretical basis for the amplification and optimization of fermentation industry. A bacteria growth dynamics model based on a Logistic equation can better describe the cell growth and inhibition; however, because the parameters and the integral constant of the model equation have no obvious biological significance, its application is limited. To establish a practical product kinetic model of ethanol fermentation, in this article, a reparameterized Logistic model was applied to correlate the ethanol concentration and time in the fermentation process, which was obtained by the analogy of the yeast growth. That is, an explicit function of ethanol concentration is given, which can combine biology and chemical engineering. As there was no yeast concentration in the model, the model was simplified so much and the parameters of it have an immediate physical interpretation that can be conveniently applied in industry. Through the research on glucose and corn starch as the raw material for ethanol fermentation, we studied the variation of ethanol concentration, total sugar concentration with time under the condition of different substrate quality, and the ratio of material to water. Then the experimental data were correlated by the reparameterized Logistic model in ethanol fermentation with glucose and corn starch. The model parameters and the consistency were good between the model and the experiments, the degree of fitting R², was greater than 0.97. The results showed that the model can be used to represent the kinetics behavior of ethanol concentration in fermentation, which has the potential to predict ethanol concentration in industrial fermentation. [ABSTRACT FROM AUTHOR]