Research On Preparation And Antioxidant Activities Of Sunflower Seed Meal Polypeptide

sunflower seed meal nutrients especially biologically active substances have not been fully utilized, because the by-product of sunflower seed when oil extraction only used as feed or fertilizer. High nutritional value of sunflower seed meal have low utilization and low value-added products. So, the problem of how to processing sunflower seed meal deeply, is urgent need to address.In recent decades, functional polypeptide industry has been rapid development, development of bio-active peptides for deep processing of sunflower seed meal protein provided a new way.Sunflower seed meal protein hydrolysates have more biological activity, such as antioxidant, cholesterol lowering, anti-thrombotic, hormones, promote growth, improve food taste etc. Variety of biologically active and good processing features making function polypeptides has become hot research.In this thesis, efficient preparation of sunflower seed meal polypeptide, purified and ultrafiltration method, and determine the antioxidant activity were studied, the main results are as follows:(1) By single factor experiment and Box-Behnken experiment to determine the optimal dual(Alkaline Protease and papain)enzymatic hydrolysis conditions: time 200 min, pH 7.6, enzyme proportion 2.5:1, the substrate concentration 2%, [E]/[S]2%, reaction temperature 50℃. In this condition, superoxide anion radical and hydroxyl radical scavenging rate was 58.06% and 46.72%.(2) By single factor experiment and Box-Behnken experiment determined the sunflower seed meal protein ultrasonic pretreatment conditions: ultrasonic time 21 min, ultrasonic power for 75% of the total power, ultrasonic temperature 34℃. Under this condition, sunflower seed meal polypeptide solution on O2-· and·OH scavenging rate was 67.11% and 52.47%.(3) By single factor experiment and Box-Behnken experiment determined the sunflower seed meal protein microwave pretreatment conditions: microwave time 3min, microwave power 500 W, microwave temperature 57℃. Under this condition, sunflower seed meal polypeptide solution on O2-· and·OH scavenging rate for 72.78% and 54.13%.(4) Single factor experiment showed that optimal desalination is: enzymatic solution pH4.5, anion and cation resin ratio of 3:2, column by column speed 8column/h. Under this condition, desalination was 84.54%, O2-· and·OH clearance rates were 57.08% and 43.62%.Polypeptide was desalted by ultrafiltration, the optimum conditions for the ultrafiltration: pressure 0.16 Mpa, flow rate 2.5mL/s, time 60 min. Under these conditions, the flux is 25.98 L/m2·h, the membrane fouling degree 0.021, O2-· and·OH clearance rates were 86.58% and 73.02%.(5) Sunflower seed meal peptides showed strong antioxidant activity. The effect for total reducing power, H2O2, ·OH, DPPH·, and O2-· scavenging were dose-dependent with concentration; The IC50 values of ·OH, DPPH·, and O2-· scavenging is 4.09mg/mL,2.69mg/mL,3.89mg/mL respectively; With the increase of days, inhibit the oxidation of soybean oil more and more obvious.Sunflower meal peptides not only has high antioxidant activity which prepared by the test above, but also provide a theoretical basis for the industrial production of sunflower meal polypeptide.