The Functional Properties Research Of Rice Bran Protein And Rice Protein

Rice bran and rice protein for its high protein nutrition,hypoallergenic unique nature,become recognized as the world's high-quality plant protein resource.Protein and rice bran protein are mainly composed of albumin,globulin,gliadin and gluten composed of various protein components with different physicochemical and functional properties.Understanding the physicochemical and functional properties of protein,rice bran protein and each grade protein components,grasping their variation under different processing conditions have practical significance for full use of rice bran and rice.In this study,we have the same variety of rice bran and rice as raw material,use the alkali soluble acid sinking method to extract protein and rice bran protein and use the method of Osborne in order to obtain the protein components of each grade of rice bran and rice.Protein samples extracted as the research object,we determine the subunit composition,amino acids,protein digestibility and denaturation temperature(DSC),and other physical and chemical properties,and discusses in different pH,concentration of NaCl and temperature conditions,samples of protein solubility and emulsification,foaming ability and the change of functional properties such as water/oily.The measurement results for samples of rice bran protein and rice protein show that rice bran protein contains mainly six subunits whose relative molecular mass is 69.5kDa,54.7kDa,47.6kDa,23.4kDa,19.7kDa and 17.2kDa respectively,and rice protein contains five subunits of 71.3kDa,69.5kDa,47.6kDa,19.7kDa and 17.2kDa;The two essential amino acids separated conform FAO/WHO recommended mode,with the full range of amino acids;vitro digestibility of rice bran protein was 68.33%,while that of rice protein is 56.86%;DSC analysis showed denaturation temperature of this two kinds of protein separated was 72.16 ? and 61.03 ?.The results of the functional properties shows that the solubility,foaming,emulsifying and emulsion stability,water holding capacity/holding oil capacity of two protein separated increases,with the pH value"s increase,while the stability of the bubble is in contrast.Protein foaming stability reached the maximum level at the isoelectric point;with the concentration of NaCl solution's increase,the functional properties of the two separate proteins show in a decreasing trend after the firstly increases.The functional properties of rice bran protein is maximum at the concentration of 0.4mol/L and that of rice protein is 0.2mol/L;with temperature of the solution is increasing,the solubility emulsifying and emulsion stability,foaming,oil retention function of both of two separate proteins show in increasing and then decreasing trend.they are maximum at the denaturation temperature of 70 ? and 60 ? respectively.foam stability and water holding capacity of two separate protein decreases with temperature 's increasing.Determination of the results of the samples of rice bran protein classification component indicates that rice bran albumin,globulin and gluten content is higher,only rice bran gluten detected cysteine;vitro digestibility of rice bran protein were graded:albumin 79.46%,globulin 77.34%,gliadin 56.59%and gluten 66.67%;The denaturation temperatures of rice bran protein are graded higher:albumin 71.72 ?,globulin 78.64?,gliadin 77.57 ? and gluten 73.51 ?.The pH,NaCl concentration and temperature effects on rice bran protein classification consistent of proteins as well as rice bran protein,has the lowest solubility at the isoelectric point around this time foaming,emulsifying and emulsion stability,water holding capacity/oil retention are underperforming,but the maximum foam stability;each protein function at a lower concentration 0.2mol/L optimum conditions of nature;protein denaturation temperature of about solubility,emulsification and foaming maximized.Determination of the results of rice graded protein components showed rice gluten protein content is higher,only rice gliadin protein does not contain cysteine.Vitro digestibility of rice Grade protein showed rice albumin protein74.68%,rice globulin protein67.78%,rice gliadin protein59.62%and rice gluten protein 61.33%.Rice grade protein denaturation temperature were albumin 62.78 ?,globulin 68.03?,gliadin 65.55 ? and gluten 70.88 ?.When away from the isoelectric point,the rice grade protein has a good water holding capacity,solubility,emulsification and emulsion stability,foaming;rice grade protein classification holding aqueous solubility and foaming in the NaCl concentration(0 to 1.0 mol/L)after the first decrease the range increases,the high ionic strength(NaCl concentration greater than 0.4?1.0mol/L)causes rice emulsifying and emulsion stability of the protein decreased classification;four hierarchical protein oil retention and foaming temperature(20?80 ?)showed a decreasing trend after the first increases water holding capacity,solubility,emulsifying and emulsion stability at around 6 0?best.Effect of each component four kinds of classification protein on functional properties of protein from rice bran and rice were studied.The results showed that albumin could improve solubility,water holding capacity and oil holding capacity of protein from rice bran and rice;gliadin could improve emulsion stability and stability of protein from rice bran and rice;glutenin could improve foam stability of protein from rice bran and rice.