The Conditions Of Enzymolysis And The Antioxidant Activity Of Its Enzymolytic Products From Defatted Corn Germ Meal

Corn germ is a by-product of corn processing, at present,its use is mainly focused on theextraction of corn germ oil, but the skimmed corn germ is used rarely. With the defatted corngerm as raw material, this paper preliminarily explores the conditions of the single enzymehydrolysis and composite double enzyme hydrolysis of corn germ, prepares antioxidantpeptides by ultrasonic not constant temperature water bath environment commonly used andpreliminarily studies the isolation and purification of antioxidant peptides and antioxidantactivity of enzymolytic products.Hydrolyze defatted corn germ meal by alkaline protease, flavourzyme, protamex andNeutrase, determine the suitable conditions of hydrolysis for each enzyme. The optimumconditions of hydrolyzing defatted corn germ meal by Alcalase are as follows: the substrateconcentration5%(w), the amount of adding enzyme5%(w/w),45℃, pH9.5, reaction time180min. On this condition, the hydrolysis degree of the hydrolysate is22.41%, the contentof the soluble protein is14.37mg/mL, the antioxidant activity is238.42U/mL. The optimumconditions of hydrolyzing defatted corn germ meal by Flavourzyme are as follows: thesubstrate concentration5%(w), the amount of adding enzyme5%(w/w),50℃, pH6.2,reaction time240min. On this condition, the hydrolysis degree of the hydrolysate is14.59%,the content of the soluble protein is12.24mg/mL, the antioxidant activity is181.46U/mL.The optimum conditions of hydrolyzing defatted corn germ meal by Protamex are as follows:the substrate concentration5%(w), the amount of adding enzyme0.81%(w/w),50℃,pH7.2, reaction time240min. On this condition, the hydrolysis degree of the hydrolysate is8.92%, the content of the soluble protein is9.46mg/mL, the antioxidant activity is156.05U/mL. The optimum conditions of hydrolyzing defatted corn germ meal by Neutrase are asfollows: the substrate concentration5%(w), the amount of adding enzyme3%(w/w),50℃,pH7.2, reaction time300min. On this condition, the hydrolysis degree of the hydrolysate is3.59%, the content of the soluble protein is5.64mg/mL, the antioxidant activity is60.08U/mLThe results show that hydrolysing the defatted corn germ meal with composite doubleenzyme can more effectively improve the efficiency of enzymolysis compared with singleenzyme hydrolysis, and the order of adding enzyme has a great influence on the hydrolysiseffect. Hydrolyze defatted corn germ meal with Alcalase and Flavourzyme, total hydrolysisdegree of hydrolysate are29.91%,, respectively, the content of the soluble protein are 16.82mg/mL,,the antioxidant activity are324.16U/mL.On the basis of the single and double enzymes, improve the oxidation resistance ofenzymolysis liquid by physical method. Enzymolysis assisted by ultrasonic is one of theimportant means of processing. Ultrasonication mainly contains the management to thesubstrate and the whole enzymolytic condition. Investigate the effects of ultrasonic power,ultrasonic time,and ultrasonic temperature on the hydrolysis degree,soluble proteins andantioxidant activity of enzymolysis by single factor and orthogonal test.The results showedthat the management of Ultrasonication in the whole enzymolytic condition can’t improvethe effect of enzymolysis. The best test conditions are as follows: ultrasonic power is214w,ultrasonic time is30min, the antioxidant activity is60.08U/mL.Separate the the peptides of antioxidant activity in the hydrolysate of defatted corn germafter ultrasound treatment by ultrafiltration, gel chromatography. After grading ofhydrolysate with ultrafiltration membrane, obtain three components and their molecularweight is more than10kDa,10-6kDa and less than6kDa respectively.Prepare the antioxidantpeptides with Sephadex G-15gel chromatography and obtain four active parts and pass theantioxidant activity screening.Preliminarily study the antioxidant activity of the enzymolytic products, including theability of removing superoxide anion radicals, hydroxyl radicals, DPPH, resisting oiloxidation and reducing. The concentration of the corn germ meal is4mg/mL,and itsantioxidant activity is526.92U/mL.The EC50of removing hydroxyl radicals, DPPH is3.27mg/mL, and2.37mg/mL,respectively. And the hydrolysate of corn germ meal has goodactivity of resisting oil oxidation and reducing.