A Study On Modification Of Oat Protein Isolate

The distribution of fat in oat was discussed,and the best defatting solvent as well as its optimized processing parameters were studied.Then oat protein isolate (OPI) was producted with the defatted oat.Two method of both enzymatic and succinylation were used to modified the oat protein isolate.enzymatic oat protein isolate (EOPI) and fully succinylated oat protein isolate(SOPI) were prepared,And their physical and chemical properties were analyzed.By the method of layer-by-layer milling and then testing the fat content,the distribution of oat fat was revealed.The fat in endosperm,accounting for total oat fat,was more than 80%.After testing of defatting effects in 4 different sizes of oat,the result showed that the material of mid-size oat had better effect in defatting.Ether and n-hexane was used to defat by extracting,the result was that the solvent n-hexane was better than ether.the optimized processing parameters for oat deffating by n-hexane were:solid to liquid 1:2.5,time 6h,temperature 60℃.And from this parameters,the content of residual oil of defatted oat was 0.60%,and the OPI was prepared with the purity of 90.0% (dry basis).The hydrolysis of OPI with four kinds of proteases was investigated,and the alcalase was chosen to modify the OPI. Based on single factor test including enzyme dosage,reaction time,and the percentage of material to water,analyzing with Box-Behnken response surface methodology,using hydrolysis degree as evaluation index,the results indicated:the optimum process parameters of EOPI were enzyme dosage 1200u/g,reaction time 30min, the percentage of material to water 2%.The solubility,emulsifying activity and foaming ability of EOPI were better than OPI;the emulsifying stability and foaming stability of the EOPI were lower than OPI.OPI were modified by succinic anhydride,and the protein with different acylation degree(21.4%,36.0%,57.8%,76.1%,99.7%) were prepared.The solubility, emulsifying and emulsion stability,foaming capacity and foaming stability of the protein went better with the increasing of acylation degree was obtained.Compared with OPI,while pH>5,fully acylated protein (SOPI) was obviously better in solubility,foaming,emulsifying and emulsion stability,but little changed in foaming stability.SDS-PAGE showed that molecular weight of EOPI was less than OPI,but SOPI slightly more than OPI.Scanning electron microscope showed that,compared to OPI, the morphology of EOPI and SOPI were changed obviously.The measure of DSC showed that ,the denaturation temperature of OPI,EOPI and SOPI were 98.21℃,110.51℃and 111.60℃respectively.