| Aflatoxins are toxic secondary metabolites produced by fungal strains. As the second most foodstuff product, corn is easily polluted by aflatoxin owing to unsuitable growing conditions or storing. Polluted corn is harmful to human and animal health, which is unfavorable to economic development. So, studying on the methods or technology to degrade or remove aflatoxins in corn has gradually been the research focus. In this paper, the aflatoxins will be degraded by Ammonia gas and wet-milling methods.Firstly, the extraction, purification, derivation and detection methods of aflatoxins in corn were defined. Then the major influential factors of ammonia gas and wet-milling methods were analyzed by single factor experiment. At last, for the ammonia gas method, by the quadratic regression orthogonal design and response surface analysis, the optimum parameter was obtained; for the wet-milling method, by the orthogonal tests L9(34) and DPS analysis, the optimum parameter was obtained, and by detecting the aflatoxin content of every step of wet-milling, the degradation effect of every step was defined.The specific results were as follows:1,The extraction, purification, derivation and detection methods of aflatoxins in corn were decided: The ground corn (2g) was mixed with 8mL of acetomitrile-water (84:16 ratio) in a 150ml triangular flask, covered with aluminum foil and moderately vibrated for 1h using a convolution alternator. The mixture was allowed to stand for 2 min and the supernatant was filtered through a qualitative filter paper. In a sharp and scale tube, 2mL of extracts was blew dry by nitrogen at 60℃. 200μL of N-hexane and 100μL of trifluoroacetic acid (TFA) was added to the nitrogen-blew tube and severely agitated for 30s using a vortex shaker. The mixture was allowed to stand for 5 min, then 900μL water: acetomitrile (9:1 ratio) was added and severely agitated for 30s. The mixture was allowed to stand for 10min and the under layer solution was centrifugated at 10000r/min for 10min. After that the supernatant was analyzed by HPLC. Mobile phase: methanol-acetonitrile-water (17:17:70, V/V/V). According to the extraction, purification, derivation and detection methods mentioned above, the recovery from corn samples was found to be above 85%, with relative variation of below 5%.2,Firstly, the effects of water content in corn, temperature, time and ammonia concentration on the degradation rate of aflatoxin B1 were evaluated using single factor experimentation, respectively. Then by the quadratic regression orthogonal design and response surface analysis, the quadratic regression between the degradation rate and every factors obtained was: Y=-514.67+12.75X1+21.13X2+6.24X3+ 1.66X4-0.16X12 +0.0038X2X1-0.005634X32-0.3922X22+0.1238X3X1-0.2904X3X2-0.0244X4X1-0.0073X4X2-0.003853X4X3-0.031049X42 (R2=0.9612); The optimum parameter obtained was corn moisture 20%, temperature 37℃, time 96h and ammonia concentration 7.05%. Under the above conditions, the predicted value of the degradation ratio of AFB1 in corn was 90.4% and its experimental value was 92%.3,Firstly, the effects of times of soaking, temperature, the concentration of Ca(OH)2 and time on the AFB1 and AFG1 in corn were evaluated using single factor experimentation, respectively. Then by the orthogonal tests L9(34) and DPS analysis, the optimum parameter was determined: times of soaking 3, temperature 25℃, the concentration of Ca(OH)2 0.015mol/L, time 24h. Under the above conditions, the degradation rates of AFB1 and AFG1 were 96.33% and 98.90%, respectively.4,The aflatoxin contents in all kinds of leavings and raffinate were detected in verification experiment of wet-milling, and the results indicated that the loss of aflatoxins in corn by wet-milling was caused by two functions: One function was the washing of water which can remove about 60% aflatoxins, the other was degradation of Ca(OH)2 which can degrade about 36% aflatoxins.
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