Preparation Of Zein And Its Hydrolysis With An Increased Antioxidants

China is one of the largest countries of growing corn in the world. In2013, the yield of corn is more than215million tons in China. Producing starch is the main form in the industry of corn deep processing. There is more than80percent of starch that is taken corn as a raw material. Corn gluten meal whose protein content reaches up to about60percent is the main byproduct in the process of producing corn starch. Corn gluten meal is generally used as animinal feed for its ideal amino acid composition according to WHO. Zein owning some biological activity is the main protein compostion in corn gluten meal. The activity of Zein will be increased after being hydrolyzed. Previous studies primarily focused on the degree of hydrolysis or the yield rate, but ignored the antioxidant activity of hydrolysate using different process. Therefore, the present work focused on optimizing recycling methods and enzymatic hydrolysis conditions in order to stimulate antioxidant activity.1) The effects of time, ethanol concentration and temperature on the antioxidant of Zein were studied. The conditions were optimized as following:time50min, ethanol concentration55%, temperature38℃. The DPPH radical scavenging rate was58.58%, and extraction rate reached72.67%, the optimal condition guarantee both antioxidant activity and extraction rate.2) The effects of different recycling methods on the yield, purity, color and antioxidant activity of Zein were studied. A method was used to recycle Zein.20to40percent cold water at the temperature of0to4℃was added to the extract solution. After removing the residual pigment, a certain amount of cold water was added to produce precipitate. The purity was3.66to10.61%higher than some reports. Compared with other methods, this method took account of the purity, yield and antioxidant activity.3) The effects of temperature, time, enzyme level, pH on the DPPH radical scavenging rate were studied. The conditions were optimized according to Zhu and Tang. Finally, the P value of master model was significant and the P value of lack of fit was not significant, thereby the model obtained was meaningful. The equation was y=236.1727-15.94658*X1-0.916158*X2-24.84083*X3-37.0715*X4+0.484*X12+0.0025*X22+1.796*X32+1.328*X42-0.037475*X1*X2-0.1875*X1*X3+1.968*X1*X4+0.0422*X2*X3+0.07965*X2*X4+1.875*X3*X4. According to ridge analysis, a saddle point was obtained which meaned that there was no maximum in this experiment. The yield of Zein hydrolysis was about10to20percents while the DPPH radical scavenging rate was significantly higher than Zein itself, which reached up to89.9percent.4) The fraction that absorbed the most in65-75minutes possessed a higher DPPH radical scavenging rate than the other fractions. According HPLC analysis, there were more than twenty-six constituents present in the hydrolysate. Results showed that the content of total amino acids rose from77.9to86.7after hydrolysis, but the contents of the individual amino acids rose at varying degrees. Most significantly, glutamic rose the highest degree from16.8to19.1. The ACE inhibitory activity reached up to69.32%at a concentration of lmg/mL and the IC50was0.82mg/mL.