Research On Preparation Of Antioxidative Soybean Peptide By Enzymic Method

The antioxidative peptide is a popular subject in nutrition and medical treatment nowdays because it has high nutritional value,functional activities. This research has practical and economic value.The substrate was soyabean isolate protein, the preparation of producing soybean antioxidative peptide using the best single proteinase, double integrated proteinase, triple integrated proteinase were studied.. With single factor and result of orthogonal experiment analysis, the optimal reaction condition was determined. The key work was as follows:1.Compared to the untreated SPI,the pretreated soybean isolated protein could improve enzmatic hydrolyzed energy, elevate enzymic utilized efficiency. The heat treated temperature was 85℃, the handling time was 20min.2.The experiment contrasted the hydrolytic effect of SPI among the pepsin,trypsin,flavour protease,alkaline proteinase,papain,extranase and the integration of the six different proteolytic integration.The best protease in the preparation of antioxidative peptide was selected.The five factors (pH value,hydrolyzed temperature,concentration of substrate,enzymic dosage, hydrolyzed time)of the hydrolysis condition influenced hydrolyze effect were studied.3.According to the six different proteinase carried on the best condition of hydrolysis to the soybean isolated protein, the antioxidative value of enzymolysis product in different conditions were measured. The best single proteinase was the alkaline proteinase. The best conditions of the preparation of soybean antioxidative peptides using the alkaline proteinase by orthogonal experiment were determined, the pH value was 9.5, temperature of enzymolysis was 53℃, concentration of substrate was 4%,hydrolysis time was 5h, enzymic dosage was 6000U/g. Under this hydrolysis condition, the antioxidative value of the enzymolysis product was 9.67mg/g.4.The best proteinase which came from the double integrated proteinase was the alkaline proteinase and the trypsin with the proportion of 3:1 (alkaline proteinase was 6750U/g,trypsin was 2250U/g) . The best condition of the preparation of soybean antioxidative peptides using the double integrated proteinase by orthogonal experiment were determined,the pH value was 9,temperature of enzymolysis was 57.5℃,concentration of substrate was 6%,the hydrolysis time was 4h, enzymic dosage was 9000U/g(the alkaline proteinase was 6750U/g ,the trypsin was 2250U/g).Under this hydrolysis condition,the antioxidative value of the enzymolysis product was 13.60mg/g.The time when the antioxidative value achieved the peaked was shorter than the the alkaline proteinase and the triple integrated proteinase hydrolyze in synchronization. 5.In the double integrated proteinase hydrolyzed separately experiment, the alkaline proteinase and the trypsin with the proportion of 3:1 (alkaline proteinase was 6750U/g, trypsin was 2250U/g) .Trypsin was used in the first two hydrolyzed hours,then the alkaline proteinase was added, when the time of enzymolysis reached 4.5h,the the anti-oxidative value of the product of enzymolysis was 13.09mg/g.6.The optimize condition of hydrolytic SPI using triple integrated proteinase which was determined by orthogonal experiment was that: the dosis of enzyme was 9000U/g,flavor proteinase,papain and bromelain with the proportion of 1:1:2,the reaction time was 5h,pH value was 7,concentration of substrate was 7%,enzymolyzed temperature was 50℃.Under this hydrolyzed condition,the antioxidative value of the product of enzymolysis was reached 10.03mg/g. According to the comparison of antioxidative value of the products of enzymolysis which were hydrolyzed by single proteinase,double integrated proteinase,double integrated proteinase hydrolyzed separately and triple integrated proteinase, finally the preparation of soybean antioxidative peptides using the alkaline proteinase and the trypsin with the proportion of 3:1 were determined.7. The hydrolysis products separated by the ultrafiltration were classified into four parts: above 5000D,between 3000D and 5000D ,between 1000D and 3000D ,below 1000D ,which were cut off by 5000D,3000D and 1000D ultrafiltration membrane .Then comparing the antioxdative activity of the four compositions,the result showed that the antioxidative peptide of the composition of which molecular weight was less than 1000D was the most powerful. So 1000D ultrafiltration membrane was choosed in the segregation.