Functional Properties Of Rice Bran Protein Hydrolysate And The Stability Of Its Composite Emulsion With Polysaccharide

Rice bran is a by-product of rice processing and its protein content is about 12-15%.Rice bran protein has the characteristics of rich nutrition,reasonable amino acid composition and low allergenicity,but its poor water solubility limits its application in the food industry.In this paper,using rice bran protein as raw material,the effect of trypsin on the structure and functional properties of protein extracted by alkali-soluble acid precipitation was firstly studied;Secondly,the enzymatic hydrolysis products with different degrees of hydrolysis were prepared into emulsions,and the effects of different p H,temperature and ionic strength on the emulsion stability were investigated.;finally,polysaccharide was selected as the emulsion stability,and its effect on the emulsion stability of rice bran protease hydrolysate was studied.The main findings are as follows:(1)The rice bran protein was hydrolyzed by trypsin,and three kinds of hydrolyzed products with different degrees of hydrolysis(1%,3%,7%)were prepared,and the natural rice bran protein was used as a control to study the structure and functional properties of the enzymatic hydrolysis.Impact.The results showed that when the degree of hydrolysis increased,the molecular weight of rice bran protein gradually decreased,and the change trend of surface hydrophobicity and endogenous fluorescence intensity increased first and then decreased.Scanning electron microscope observation showed that the enzymatic hydrolysis made the protein structure loose.And there is a smaller block structure,the secondary structure of rice bran protein after enzymatic hydrolysis is more flexible,the content of β-sheet is reduced,and the structure is changed to random coil and α-helix;In addition,enzymatic hydrolysis improves the solubility of rice bran protein,emulsifying,emulsifying stability,foaming,and foaming stability reached the highest value when the degree of hydrolysis was 3%.With the increase of the degree of hydrolysis,the water holding capacity was significantly reduced,and the oil holding capacity was significantly improved.(2)In order to explore the stability of rice bran protein emulsion,the stability of rice bran protein and three enzymatic hydrolysis products under different p Hs,temperatures and ionic strength was analyzed.The results showed that the average particle size of the four emulsions changed similarly at p H3-8,and it was easy to aggregate when approaching the protein isoelectric point,and the average particle size increased.The 3% hydrolyzyme was stable at Na Cl < 100 mmol/L(p H7),temperature < 90 °C,and p H 7-8.(3)Soy soluble polysaccharide and sodium carboxymethyl cellulose were selected as emulsion stabilizers to study the effect of polysaccharide on rice bran proteolysis products.The results showed that when the polysaccharide concentration was 0.3%,the two emulsions remained stable at p H3.5,and the effects of different environmental factors(p H,temperature,and salt ionic strength)on the RBPH-CMC and RBPH-SSPS composite emulsions were investigated.It was found that the RBPH-CMC composite emulsion remained stable to p H(2-7)and salt ion(0-400 mmol/L,p H3.5)treatments,while RBPH-SSPS composite emulsion had good stability to heat treatment(30-90 ℃,p H3.5).