Study On Antioxidant Activities Of Enzymatic Hydrolysates Of Whey Protein And Application On Chilled Fresh Duck Preservation

The present study optimized the hydrolysis parameter of whey protein, investigated antioxidative activity in vitro and stability of whey protein hydrolysates, and applied hydrolysates to chilled duck preservation. The results showed:The study compared antioxidative activity of whey protein hydrolysates obtained by alcalase, papain, neutrase and trypsin by scavenging hydroxyl radical.The results indicated that hydrolysaste of these four enzymes exerted antioxidative activity, and trypsin possess stronger antioxidant potential than others.Therefore, trypsin was determined to be used to hydrolysis whey protein.The effect of different factors on the antioxidant activity of whey protein hydrolysates were discussed. When the scavenging ability of hydroxyl radical as response value, the enzymatic hydrolysis parameter were optimized through orthogonal experiment. The results as follows:the optimum parameter of whey protein hydrolysis by trypsin were pH6.5,hydrolysis temperature 40℃,enzymatic concentration[E/S] 2000:1(U/g), concentration of whey protein 6% and hydrolysis time 5h. Moreover, the results indicated that there was no positive correlation between antioxidative activity and hydrolyzing degree of hydrolysate of trypsin from whey protein.The different assay systems in vitro were used to evaluate the antioxidative activity of the whey protein hydrolysates, including hydroxyl radical scavenging activity, superoxide anion radical scavenging activity, DPPH radical scavenging activity, reducing power and antioxidant value. The results indicated that hydrolysates of whey protein hydrolysis by trypsin showed strong antioxidative activity in vitro, and all these effects were dose-dependent. The results also showed that whey protein hydrolysates possess weaker antioxidant potential than ascorbic acid under same concentration.Temperature and pH showed significant effect on stability of antioxygenic property of Whey protein hydrolysates, the antioxygenic property in acidic condition was better than in alkaline condition. Hydrolysates showed high antioxygenic property under temperature 5℃,and antioxygenic property decreased with temperature increasing, that was to say that low temperature and acidic condition were propitious to exert antioxygenic property of Whey protein hydrolysates.Researching the application of whey protein hydrolysates on chilled duck preservation, observing the effect of whey protein hydrolysates used in duck preservation based on sensory index, physicochemical index and microbiological index. The results indicated that whey protein hydrolysates showed positive effect on prohibiting the oxidation of lipid during the storage period, but there was no positive correlation between the effect and the concentration of whey protein hydrolysates.