Study On Two-step Steeping Technology Of Corn Starch

This paper aimed at the shortcomings of long steeping time,pollution heavy and low production efficiency of traditional steeping technology, using the enzymatic two-step steeping technology instead of the traditional steeping with sulfur dioxide. The main results were as follows:1. With 100g corn, the optimum conditions of the first step steeping technology of two-step steeping technology is steeping temperature of 52℃and steeping time of 3h. The second step steeping technology by single factor experiment, starch rate as main index, sample dissloution rate, protein content and total sugar content of steeping water as auxiliary indexes, studied the optimum value of steeping temperature, steeping time and acid protease addition when starch rate is highest. The results were as follows:when steeping temperature is 50℃, steeping time is 2h and acid protease addition is 600u/g, the highest starch rate is 65.2%.2. Base on single factor experiment, with experimental design software Design Expert, using Box-Behnken Response Surface Methodology(RSM), designing optimization experiment between starch rate and steeping temperature, steeping time and acid protease addition to obtain the optimum condition of factors of the second step steeping technology. According to the Box-Behnken RSM analysis, we got the quadratic regression equation between starch rate and factors:Y=64.48+1.30X1+1.66X2+1.19X3-0.58X1X2-0.22X1X3-0.50X2X3-1.74X12-2.62X22-1.91X32 through the regression equation analysis and experiment, we obtained the optimum condition of factors of the second step steeping technology:steeping temperature is 51.25℃, steeping time is 2.26h, acid protease addition is 703.22u/g and then starch rate is 65.05%. We did a verification test by using the optimized conditions of steeping temperature is 51℃, steeping time is 2.25h, acid protease addition is 700u/g and the starch rate is 64.9%.3. We did a 20Kg corn enlargement experiment to test the conditions of two-step steeping technology. The results were as follow: We used mechanical crusher instead of manual to crush corn and to removal corn husk and germ in the first step steeping technology, steeping temperature is 52℃, steeping time is changing to 4h. In the second step steeping technology, corn was from coarse grinding to break into 6-10 sections, steeping temperature is 50℃, steeping time is changing to 5h, acid protease addition is changing to 600u/g, the highest starch rate is 71.02%, crude protein content is 0.42%.