Extraction,Purification And Antioxidant Activity Of Water-soluble Peptide In Soy Sauce

Soy sauce is a traditional femented soybean products in our country.In the process of the fermentation ofsoy sauce,Soy protein was decomposed by Enzyme produced by microorganism, produced a large numberof peptide,which can fight aging、lower blood cholesterol、fight cancer、regulat insulin and so on. The peptidehas a strong biological activity. The purpose of this research is to evaluate the peptides’ antioxidant activity.The material used in this research was soy sauce made up by non-genetically modified soybeans. After diluting,bleaching, desalination, ultrafiltration, Sephadex separation and purification, and the peptide produced hashigher antioxidant activity. The soy sauce antioxidant peptide was attained with the high performance liquidchromatography. Main contents and conclusions are as follows:1Decolonization solution of soy sauce peptide. In order to separate and purify the bioactive peptide, needto get rid of the color material of soy sauce. Based on decoloring rate and loss of soy sauce peptide detected,the adsorptive decolorization technology of the soy sauce peptide solution was investigated. then optimalconditions were carried out by response surface methodology. Optimal technical conditions were as follows:1.8%activated carbon（w/v,%）,temperature55℃and decoloration pH of6.4. Under the optimal conditions,thedecoloring rate was80.9%,in further verified experiment and the difference was not significant with predictedvalue of81.1%.2Desalination of soy sauce peptide. In order to remove the salt of soy sauce, be good for the separationand purification of active peptide, The salt and peptide adsorption rate were used to analysis the effect ofdesalination conditions of soy sauce. The results showed that the Resin â…£ macroporous exchange resin wasappropriate adsorbent. The results indicated that the optimum condition for desalting was obtained as follows:loading flow rate of1mL/min loading sample concentration of8mg/mL, flow speed of2mL/min and75%alcohol as eluent. Under this condition, the ratio of soy sauce polypeptides desalination reached to95.3%, andthe recovery of peptides was88.5%. Moreover, its antioxidant activity was enhanced. In conclusion, Resin â…£macroporous exchange resin has excellent and comprehensive adsorption property.3Purification of soy sauce peptide. Separate of soy sauce peptides using ultrafiltration and evaluate itsantioxidant activity. Purify and separate the peptide with molecular weight less than3kDa. Used asingle-factor test method:SephadexG-15, loading sample concentration was1.2mg/mL, sample3mL, the flowspeed was2mL/min. After the separation, we got SP₁, SP₂, SP₃, SP₄. The strength of antioxidant activity wereSP₂＞SP₄＞SP₁＞SP₃. Determine of SP₂with high performance liquid chromatography to attain a graph of theantioxidation activity of soy sauce peptide.4Research on antioxidation activities of soy sauce peptide. The antioxidative activity of soy saucepeptide was studied from four aspects of reducing power, scavenging activity for DPPH free radical,scavenging activity for superoxide radicals, scavenging activity for hydroxyl free radicals, and it is comparedwith Vc. The experimental results show, soy sauce peptide have different scavenging effect in these radicalsystems and have reducing power, scavenging activity for DPPH free radical IC₅₀is5.59mg/mL, which islower than Vc, scavenging activity for superoxide radicals IC₅₀is16.29mg/mL is lower than Vc, scavengingactivity for hydroxyl free radicals IC₅₀is4.67mg/mL is lower than Vc, soy sauce peptide shoud be have further purification..