Study On The Antioxidantive Activity Of Enzymatic Hydrolysates Of Corn Proteins

Corn protein is abundant enough and low cost in our country. It is regarded as the bestsource for production of medicinal peptides, functional food and additives since its especialamino acid composition. Most physiological functions of corn protein hydrolysates arerelative to its antioxidant activity. As a result, it keeps a research priority to raise theantioxidant activity of corn protein hydrolysates. The preparing technology of corn proteinhydrolysates was optimized, the antioxidation of the hydrolysates in oil systems and ageingresistance to steamed bun are discussed.The relationship between the antioxidant activity and degree of hydrolysis of cornprotein hydrolysates was evaluated. It confirmed that the reducing power and scavengingactivity of DPPH radical could be used to evaluate the antioxidativity of corn proteinhydrolysates. Then hydrolysis technologies of neutrase, alcalase and papain were optimizedby response surface methodology. On the basis of the optimum conditions of single enzymatichydrolysis, corn protein hydrolysats were prepared by double-enzyme two-step hydrolysis.Results showed that double-enzyme two-step hydrolysis were more effective to releaseantioxidant substances. Considering all factors, the optimal hydrolysis conditions of preparinghydrolysates with high antioxidantive activity were selected as: corn protein was hydrolyzedfor1h at the optimum conditions of papain by papain, and then hydrolyzed for2h at theoptimal technological conditions of alcalase by alcalase. The reducing power and scavengingactivity for DPPH radical of the hydrolysates were0.725and69.6%, respectively. The cornprotein hydrolrsates were prepared under these conditions and dried by freezing, and theantioxidation of the products in vitro was discussed. The results showed that the reducingpower of the hydrolysates at4mg/mL concentration was equal to100μg/mL VC, and theDPPH radical scavenging activity was30%of100μg/mL VC. Meanwhile, the inhibitoryeffects of corn protein hydrolysates on lipid oxidation have been resceached. The hydrolysateshad certain inhibitory effects on lipid oxidation, but they were inferior to BHA and TBHQ atthe same adding level. Antioxidant activity of corn protein hydrolysates prepared bydouble-enzyme (papain and alcalase) was significantly improved.The staling resistance of corn protein hydrolysates to flour and steamed bread weredemonstrated, the treatment adding0.06%hydrolysates showed the best effect, and thehydrolysates was benefit to long-term retrogradation of steamed bread. Corn proteinhydrolysates has potential to use as an additive to improve the preservation qulity of flourproduct.