Optimization of Process Parameters for Microwave Sterilization of Maize Based on Response Surface Methodology

Abstract. Maize, as the main energy source of food and animal feed, is liable to suffer from fungal infection in the process of storage. Microwave treatment can effectively improve the sterilization effects of agricultural products including maize. In the present study, four factors affecting efficacy of microwave sterilization were investigated such as microwave power, sterilization time, load and moisture content of maize. The design of rotation regression orthogonal combination was used to analyze the four controlled variables: microwave power (170, 340, 510, 680 and 850 W); sterilization time (50, 60, 70, 80 and 90 s); load (50, 100, 150, 200 and 250 g); moisture content (12, 14, 16, 18 and 20%). The results showed that the primary and secondary order of factors influencing the sterilization rate was microwave power, sterilization time, load and moisture content in sequence, while the order of interaction effect of these four factors was the microwave power and sterilization time, the microwave power and load, the moisture content and microwave power, moisture content and sterilization time. The regression equation of microwave sterilization was established and the regression effect was significant. Based on optimization of the regression model, the maximum sterilization rate (99.68%) was obtained when the microwave power, sterilization time, maize load and moisture content were 680 W, 64 s, 200 g and 12.96%, respectively. The application of this analysis method for optimizing the microwave sterilization of maize was discussed.