Optimization of Solid-State Ethanol Fermentation with the Soluble Carbohydrate in Sweet Sorghum Stalk Using Response Surface Methodology

摘要

In order to improve the ethanol yield efficiency through solid-state fermentation with sweet sorghum stalk, the Plackett-Burman design was applied for screening the impact of fermentation temperature, initial pH, yeast inoculation ratio, supplement dose of (NH_(4))_(2)SO_(4), K_(2)HPO_(4), and MgSO_(4)(centre dot)7H_(2)O on ethanol yield efficiency. Meanwhile, according to the screened results, the Box-Behnken design was employed for the optimization of the main factors. The results of Plackett-Burman analysis indicated that the importance sequence of the mentioned 6 factors was the supplement dose of K_(2)HPO_(4) > the supplement dose of (NH_(4))_(2)SO_(4) > initial pH > yeast inoculation ratio > fermentation temperature. Three significant factors, including temperature, supplement dose of (NH_(4))_(2)SO_(4) and supplement dose of K_(2)HPO_(4), were chosen as the independent variables. Box-Behnken design was conducted to obtain the multivariate quadratic regression model, which was used to predict ethanol yield efficiency. The optimum conditions for solid-state ethanol fermentation of sweet sorghum stalk by response surface methodology were determined as follows: fermentation temperature 30.72 deg C, (NH_(4))_(2)SO_(4) supplement dose 0.202percent, K_(2)HPO_(4) supplement dose 0.127percent. The maximum predictive ethanol yield efficiency of 93.0percent was obtained at the optimized conditions. Ethanol yield efficiency of the verification experiment was 93.4+-0.7percent, suggesting that the multivariate quadratic regression model was valid for the prediction.