Research On Soybean Antioxidant Peptide Got By Ultrasonic-assisted Enzymatic Hydrolysis

As a kind of the raw material, soy protein isolate which protein content was more than90percent was the low temperature defatted soybean meal in the domestic by advanced production and processing technology. soy protein was interested and researched in the food industry because it contained many kinds of organism required amino acids and the proportion was balanced. Thereforey, in this experiment, the soy protein isolate was obtained from the low temperature defatted soybean meal by the alkaline-soluble and acid precipitation in the lab. Then the soy protein isolate obtained was as the enzymatic hydrolysis of raw materials, the Alcalase enzyme and flavourzyme was selected as the enzymatic hydrolysis of soy protein isolate enzyme, the soybean antioxidant peptides was got by ultrasound and enzymatiction. As the evaluation was degree of hydrolysis and reducing power, the influence of ultrasound on the effect of soybean protein hydrolyzation was determined by different hydrolysis conditions, the supernatant of soybean peptide was analysed by high performance liquid experiments to study the change of enzymaticed things. The best enzymaticed conditions of ultrasound-assisted enzymatic was obtained by the single factor experiment and response surface experiments. soybean peptides obtained by enzymaticing was separated by ultrafiltration, then obtained five kinds of different molecular weight of soybean peptide, with the evaluation of reducing power and scavenging capacity of free radicals, antioxidant activity of soybean peptide obtained was analyzed, and found that soybean peptide has strong antioxidant activity, It can be used as an antioxidant thing added to the food system.In this study, the protein content of soy protein isolate which was got by alkali-dissolvetion and acid-precipitation was89.22%. The protein content was improved26.11%more than protein content in soybean meal. As an indicator was the degree of hydrolysis and reducing power, wo got the best hydrolysis conditions of soy protein by single factor experiments and response surface experiments, which was that ultrasonic temperature was50.05℃, ultrasonic power was1500W, ultrasonic time was20.76min, substrate concentration was5.05%, below in this conditions, measured the degree of hydrolysis of soy protein was38.10%, the reducing power was0.041.The soybean peptides were got by ultrasound and enzyme. After separated by ultrasound membrane, wo got five kinds different molecular weights components from the soybean peptides, respectively were A1(<1000Da), A2(1000Da-3000Da), A3(3000Da-5000Da), A4(5000Da-10000Da), A5(>10000Da), and the contents were78.13%,10.68%,4.19%,3.04%,3.96%. As anindicator was reducing power and the scavenging hydroxyl radical、superoxide radical、DPPH radical. It was found that the reducing power and scavenging radical effect of A1were all better than other four components. When the concentration was10mg/mL, the reducing power which was largest as1.035, the scavenging of DPPH radical which was largest was85.47%, the scavenging of superoxide radical which was largest was78.65%, the scavenging of hydroxyl radical which was largest was83.41%.