Study on optimization of reducing sugar yield from corn stalk based on microwave-assisted acid pretreatment process

In this paper, the optimal process condition for microwave-assisted acid pretreatment of the corn stalk was investigated by Central-Composite design using Response Surface Method. Effects of microwave power, reaction time and acid concentration on reducing sugar yield were inspected. Also, analysis of corn stalk before and after the treatment was conducted with ultra depth microscope. The test result shows that, the sequence of factors is: acid concentration>reaction time>microwave power, and the interaction of microwave power and reaction time is significant; The optimal process condition is: microwave power 900W, reaction time 20min, acid concentration 2%, reducing sugar yield 230.9 mg/g. Through the microwave-assisted acid pretreatment, the fiber structures of the corn stalk were destroyed effectively, the treatment increases the degree of surface roughness, improves porosity, thus the rate of enzymolysis was enhanced. The p-value of regression model is 0.0002, and the p-value of Lack of fit is 0.1298, which indicates the regression equation is significant and the model fits well.