Study On Preparation Of Peanut Protein And Peptide And Its Purification

Ultrasonic Wave was used to assisted alkali extraction and acid precipitation ofpeanut protein isolate from defatted peanut powder. Based on the single factormethod ,the response surface analysis results shows that the Ultrasonic Wave-assistedExtraction condition is: ultrasonic power 210W, ultrasonic time 30min, ultrasonictemperature 40℃,solid to liquid ratio 1:10.7and under this improved condition theextraction yield can reach 80.09%.The best enzyme selected from five common enzymes was coupled with microwaveto prepare peanut peptides. The main influencing factors of microwave coupledenzymatic method were optimized by response surface analysis. Papain is the bestenzyme. The optimal conditions were obtained as follows：The microwave extractiontime is 10.5min; the power is 600W; the concentration of substrate is 4%; theenzymatic temperature is 48℃; The enzyme quantity 7500u/g; the pH value is7.2．Under these conditions, peanut peptides with the yield of peptides (TCA-NSI)62%, the degree of hydrolysis (DH) 25.89%.Which is higher than single proteasehydrolysis and single microwave hydrolysis.Macroporous adsorptive resin was compared with nanofiltration in the process ofdesalting, the optimum conditions of macroporous adsorptive resins were obtained:hydrolyte flow rate 1.2BV/h, concentration of peptide is 20mg/ml, 75% enthanol asthe eluent. The desalting rate was 85.43% which is more than nanofiltration 56.43%.The peptide recovery rate was 69.38% which is less than nanofiltration 84.37%.The peanut peptide was obtained by hydrolysis defatted peanut flakes, which wasseparated by different ultrafiltration membranes to three different size peptide. And then the reducing power, hydroxyl radical scavenging, antioxidant and DPPH radicalscavenging were determined of different concentration and molecular weight ofpeanut peptide. The experimental results show that the peanut peptide had relativelystrong antioxidant activity, and with the different molecular weight of peanut peptide,they showed different antioxidant activity. The molecular weight less than 3KDshowed the strongest antioxidant activity, 3KD~5KD is the next, the molecularweight more than 5KD showed the worst antioxidant activity. And the molecularweight less than 1KD showed the best ACE inhibitive activity.