| Bean waste contains plenty of protein. Protein was extracted from Bean waste by hydrolysis of alkaline proteinase. Effects of material-liquid ratio, temperature, pH value, enzymolysis time and enzyme addition ratio on protein extraction ratio were studied. Orthogonal experiment was established to improve the protein extraction ratio. Finally, the optimum conditions of protein extraction were as follows: material-liquid ratio 1:50, temperature 55℃, pH value 10, enzymolysis time 4h and enzyme addition ratio 1%.Study on the modification methods of protein in soybean waste by alkaline extraction and acid precipitation, and research a best method to strengthen functional characteristic of the protein much further. Some kind of modification methods were studied as follows: ultrasonic wave modified method, microwave modified method, phosphorylation method, acylation method and enzyme (alkaline proteinase, trypsin, and papain) modification methods. The ultrasonic method is the best method on soybean waste protein modification. Finally, the solubility and emulsifying capacity get high levels when the conditions of protein soybean waste treatment with ultrasonic modification method were as follows: ultrasonic power 800W, material-liquid ratio 1:16 and process time 5 minutes.Zymohydrolysis on protein from soybean waste under the optimum condition of alkaline proteinase kept for 2hr. The zymohydrolysis liquid has optimum efficiency of scavenging superoxide radical (·O2-). Soybean waste protein was processed under the condition above and got the zymohydrolysis liquid. Processed the liquid with Sephadex G-25 column chromatography separation, and evaluated the polypeptide activity of anti-oxidation after separation. The polypeptide has marked effect of scavenging superoxide radical (·O2-)and hydroxy radical (·OH), simultaneously has obvious result of suppressing malonaldehyde (MDA) which is a kind of autoxidation product from homogenate of little mouse livers.
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