Preparation And Characterization Of Antioxidant Peptides From Black Wheat Bran

In this paper,black wheat bran was used as raw material to study the related conditions of protein extraction and enzymolysis,and the best enzymolysis process was determined.Then the enzymolysis products were separated and purified to obtain antioxidant peptides,and the effects of different conditions on its functional properties and stability were studied.The main research contents and results are as follows:(1)The ultrasonic-assisted alkali method was used to extract black wheat bran protein,and the extraction conditions were optimized by single factor and response surface method.The conditions for obtaining the highest extraction rate of black wheat bran protein were:ultrasonic power 350 W,temperature 55?,p H 9.3 and time 80 min.The enzymatic hydrolysis of black wheat bran protein was carried out by two-enzyme step-by-step enzymatic hydrolysis.The effects of enzyme type,p H value,temperature,time and enzyme dosage on the yield of peptide,degree of hydrolysis and total antioxidant capacity(TEAC)were studied.The results showed that the p H value of alkaline protease was 9,the enzyme activity was 18000 U/g,the time was 2 h,and the temperature was 50?,while the p H value of the flavor enzyme was 6,the temperature was 50?,and the time was 2 h.Under the condition of 10000 U/g addition,the black wheat bran protein was enzymatically hydrolyzed sequentially.At this time,the peptide yield was 52.36%,the degree of hydrolysis was22.74%,and the TEAC value was 8.47?mol/g.(2)Use TEAC value and superoxide anion scavenging ability as indicators to separate and purify the enzymatic hydrolysis products to obtain peptides with higher antioxidant activity;and study the p H and temperature of the solubility,foaming and foaming of antioxidant peptides stability,emulsification and emulsification stability,water retention and oil absorption.The results showed that after the separation of dextran gel,four components(F1,F2,F3,F4)were obtained.The antioxidant activity of F4 components was significantly higher than that of the other three components.The F4 components were separated by ion exchange chromatography,and five components(F4-1,F4-2,F4-3,F4-4,F4-5)were obtained.Among them,the antioxidant activity of the F4-3 component was significantly higher than that of the other four components,so select F4-3 components to study the functional characteristics.The solubility of black wheat bran antioxidant peptides is generally higher,and the lowest value appears at the isoelectric point p H value of 5.When the p H value gradually increases,the foaming property and emulsification stability both increase first and then decrease.Foam stability,emulsification,water retention,and oil absorption all show a trend to first decreasing and then increaseing with the increase of p H;when the temperature is in the range of 25-75?,the functional properties of black wheat bran antioxidant peptides are all in order to increase first and then decrease,the temperature when different properties reach the highest point is different;in addition,the increase in the concentration of antioxidant peptides also has a certain promotion effect on its functional properties.(3)To study the effects of temperature,p H,Na Cl,potassium sorbate,metal ions and in vitro digestion on the activity of antioxidant peptides from black wheat bran.The results show that black wheat bran antioxidant peptides can maintain a certain degree of antioxidant activity in a temperature environment below 60?;after alkaline environment,high salt concentration,Zn²⁺and Cu²⁺treatments,their antioxidant activity will decrease significantly;potassium sorbate,K⁺and Ca²⁺have little effect on the activity of antioxidant peptides,and the overall activity can be maintained at a high level;after in vitro digestion,the black wheat bran antioxidant peptides have a certain tolerance to the digestion of different proteases.Conducive to play an antioxidant effect in the body.