In order to investigate the influence of different liquefied mash pH on corn ethanol production, a simultaneous saccharification and fermentation process model based on the current industrial corn ethanol production process was established. Based on the stability of this process model, the properties of liquefied mash, the performance of CO2 mass loss during ethanol fermentation and the main indexes of mature fermented mash were measured. Results showed that compared with liquefied mash pH 5.2 and 4.8, the reducing sugar content obtained in liquefied mash of pH 5.6 increased by 16.48%(P<0.01) and 121.08% (P<0.01), respectively. The process model on CO2 mass loss was stable, with the highest standard deviation only at 0.55 (pH=5.2, 48 h). At the same time, with the increase of pH of liquefied mash from pH 4.8 to 5.6, the CO2 mass loss speed became low. Compared with liquefied mash pH 5.2 and 4.8, the ethanol content obtained in mature fermented mash at pH 5.6 increased by 0.32% (P>0.05) and 1.18% (P<0.05), respectively. Meantime, the residual starch content obtained in mature fermented mash at pH 5.6 was higher by 0.66% (P>0.05) and 5.26% (P<0.05), respectively. Additionally, the total residual filtered sugar content in mature fermented mash at pH 5.6 was significantly lower by 3.61% (P<0.01) and extremely significantly higher by 11.93% (P<0.01). This study indicated that it should be necessary to adjust reasonable liquefied mash pH on the α-amylase as well as reducing sugar content in the liquefied mash on the initial ethanol fermentation.
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