Extraction,Purification And Antioxidant Activity Of Water-soluble Peptide In Soybean Paste

In the process of the fermentation of soybean paste,the composite enzymes decomposed soybeans and wheat flour produced peptides.The peptide has a strong biological activity.The purpose of this research is to separate and purify the water-soluble peptides from soybean paste and evaluate the peptides’ antioxidant activity.The material used in this research was soybean paste made up by non-genetically modified soybeans.Water extraction method was adopted,after bleaching,desalination,ultrafiltration,Sephadex separation and purification,and the peptide produced has higher antioxidant activity.The soybean paste antioxidant peptide was attained with the high performance liquid chromatography.Main contents and conclusions are as follows:1 Extraction of peptide from soybean paste.The soybean paste used was commodity.Water extraction method was adopted,and the results show that the liquid ratio was 1:11.9,with the extraction temperature of 56℃ for 61 min with pH of 6.0.In this condition,the extraction rate was 32.60±0.5%.2 Decolorization solution and antioxidant activity of soybean paste peptide.In order to separate and purify the bioactive peptides from soybean paste and evaluate its antioxidant activity,the decolorization effects of activated carbon and antioxidant activity of the decolorized soybean paste aqueous solution were investigated.Based on a single-factor test method,an orthogonal experiment was designed.The results show that the proper decolorizing conditions were 6% of the amount of activated carbon,decolorizing temperature of 35 for 40 ℃minutes with pH of 5.0.In this condition,the decolorization rate of 59.85% and peptide retention rate of 66.35% were obtained,the decolorization solution revealed superoxide anion radical scavenger activity level of 270.43 U/L,the cupric reducing antioxidant capacity of 7 980 μM and the hydroxyl radical scavenger activity of 820.43 U/mL.In conclusion,activated carbon possessed a better decolorization effects for soybean paste peptide aqueous solution,and caused higher peptide retention rate and antioxidant activity.3 Desalination of soybean paste peptide.The method of resin adsorption and dialysis method are used for comparison.The results show that the 001×7 strong acid styrene cation exchange resin was appropriate adsorbent,the optimum desalination condition is as follows: loading sample concentration was 4 mg/mL,the pH=8.0 of 50% alcohol was eluent,the flow speed was 30 r/min.Optimally,the ratio of desalination reached to 91.28%,and the recovery of peptides was 88.54%.However,there was little sodium in the resin adsorption soybean paste peptide solution.In contrast,the results of dialysis method show that desalination rate was 68.63% and the recovery of peptides was 62.75%.There were no sodium ions left.But more peptides were lost and its antioxidant activity was enhanced.This study suggested that desalination of soybean paste peptide with cation exchange resin was better.4 Purification of soybean paste peptide and attained with the high performance liquid chromatography Separate of soy sauce peptides using ultrafiltration and evaluate its antioxidant activity.Purify and separate the peptide with molecular weight less than 3 kDa.Used a single-factor test method: Sephadex G-15,loading sample concentration was 0.6 mg/mL,sample 2 mL,the flow speed was 30 r/min.After the separation,we got F₁,F₂,F₃,F₄.The strength of antioxidant activity were F₄>F₁>F₂>F₃.Determine of F₁ and F₄ with high performance liquid chromatography to attain a graph of the antioxidation activity of soybean paste peptide.