Study On The Extraction And Enzymatic Modification Of Rice Bran Proteins And Its Functional Properties

Rice bran is the renewable agricultural with great development potential in our country, it’sprotein had high nutrition, low allergy unique nature, which was recognized as a quality plantprotein resource in the world. In order to increase the use of plant protein species and the valueof rice bran, using Osborne classification method for preparing protein in turn obtain rice branalbumin, globulin, prolamin and glutelin.（1）To determine the optimal extraction technology of four proteins were:①Solid-liquidratio was1:11, extraction time was2.25h, extraction temperature was45℃, get albuminextraction rate was62.83±0.04%;②Solid-liquid ratio was1:11, extraction time was2.0h, extraction temperature was52.5℃, get globulin extraction rate was23.94±0.03%;③Solid-liquid ratio was1:10, ethanol concentration was75%, extraction time was2.0h, getprola min extraction rate was5.07±0.21%;④Solid-liquid ratio was1:7, extraction time3.0h, pH9.0, get glutelin extraction rate was21.82±0.08%.（2）The optimal hydrolysis conditions of four proteins were:①Enzyme concentration7000U.g-1, pH10.19, hydrolysis temperature58.13℃, hydrolysis time2.26h, the albumindissolution rate of theoretical value was96.92%and the test actual value was94.54±0.24%;②Substrate concentration was4.42%, hydrolysis pH8.19, hydrolysis time2.15h hydrolysistemperature52.08℃, the globulin dissolution rate of theoretical value was89.64%and the testvalue was89.21±0.08%;③Substrate concentration4.94%, pH8.25, hydrolysis temperature56.45℃, hydrolysis time1.68h, the prolamin dissolution rate of theoretical value was38.21%and the test actual value was35.07±0.31%;④Enzyme concentration28.85%, hydrolysis pH10.76, hydrolysis temperature56.79℃and hydrolysis time2.58h, the glutelin dissolution rateof can theoretical value was51.46%and the test actual value was51.28±0.31%.（3）Comparative analysis on the functional properties of four proteins which before andafter modified, the results showed that:①Solubility: The NSI value of albumin, globulin, prolamin and glutelin were22.93%,64.35%,113.85%,239.64%;②Emulsifying properties: The EA value of albu min, globulin, prola min and glutelin were36.90%,93.81%,83.99%,76.12%; the ES value of albumin, globulin, prolamin and glutelin were20.13%,36.47%,42.04%,26.86%;③Foaming properties: The FA value of albumin, globulin, prolamin and glutelin were1.4times,1.4times,1.3times,1.5times; The FS value of albumin, globulin, prolamin and glutelinwere25.41%,70.31%,68.27%,37.38%.④Water holding capacity: The water-holding capacity value of albumin, globulin, prolaminand glutelin were4.23times,4.14times,3.11times,3.67times.⑤Oil absorption: The oil-absorption value of albumin, globulin, prolamin and glutelin were2.10times,1.98times,1.82times,2.09times.The functional properties of four hydrolysis products were significantly improved. Over all,the enzymatic modification can improve both dissolution rate and the functional properties ofrice bran four proteins, which has high developing value and broad application prospect.