Optimization And Dynamics Of Simultaneous Saccharification And Fermentation In Ethanol Production During Cold Enzyme Starch Hydrolysis In Very High Gravity Cassava Mash

Ethanol is widely used in renewable fuels, food industry, chemical engineering and medicine. As one of the most important materials for daily application and energy crisis remissiom, process technology improvements for reduction of procuction cost and environmental contamination were focused by energy sector. In the present study, an optimization and dynamics of simultaneous saccharification and fermentation in ethanol production during cold Enzyme starch hydrolysis in very high gravity-cassava mash was studied. The main results were as follows:At the fisrt part of the study, characterizations of cassva starch and commercial Saccharomyces cerevisiae strain for very high gravity fermentation were determined. The composition of cassava, fluid and shear thinning characteristics of very high gravity cassva mash and the expansion potential of cassva starch were estimated. Meanwhile, the gelatinization condition of very high gravity cassve was also determined by single-factor experiment. Through the analysising of the Saccharomyces cerevisiae strain, the fermentation characterization, glucose and alcohol tolerance was also determined.Plackett-Burman design (PBD) was used to study 19 factors that could potentially inffuence ethanol production. Gravity, particlesize, initial pH, and fermentation temperature were identiffed as key factors that signiffcantly increased final ethanol concentration. The mainand interaction effects of these factors were subsequently evaluated based on a quadratice quation generated by Central composite design (CCD) using response-surface methodology (RSM). Under the optimized very high-gravity conditions, the final ethanol concentration obtained from experiment increased to15.03%(wt.%). The optimal condition resulted in an overl.87-fold increase in final ethanol concentration when compared with the original condition.Response surface methodology was used to optimize the effects of amylase, glucoamylase, liquefaction temperature and liquefaction time on S. cerevisiae biomass, ethanol concentration and starch utilization ratio in cold enzyme starch hydrolysis of very high gravity-cassava mash. The maximum biomass obtained was 4.380×108 cells/ml; the maximum ethanol concentration obtained was 18.25%(wt.%); and the maximum starch utilization ratio obtained was 94.64%.The hydrolysis condition was subsequently evaluated by multi-objectives optimized through weighting coefficient methods. The weighting coefficients method of dynamically Pareto-optimal solutions would allow the designer to visualize and assess trade-offs among the objectives, to explore compromise solutions, and to make decisions based on realistic goals.Based on the analysis of the technology of simultaneous saccharification and fermentation in ethanol production during cold Enzyme starch hydrolysis in very high gravity-cassava mash, a two enzyme nonsynchronous synergism model is constructed. The model describes the different hydrolysis enzyme treatment for ethanol production from starch. Through curve approximation, experimental analysis and calculated by fitting experimental the parameter of this model was obtained. The model is shown to be forecast accuracy and generalization capability through verification by biomass strategy, ethaol strategy and starch utilization ratio strategy.