Research On The Effect Of Heat Treatment On The Physical, Chemical And Functional Properties Of Oat Protein

Oat is a kind of nutritious and healthy cereal which is rich in protein,fat and dietary fiber and favored by consumers around the world.Heat treatment can prolong the shelf life of oat products,but has a negative impact on the nutrition,structure and function of oat protein.In this study,based on the analysis and comparison of protein nutritional value and amino acid composition of oats and other four kinds of common cereals,the effects of heat treatment on physicalchemical and functional properties of oat protein isolation and globulin were explored,and the effects of heat treatment on oats were further elucidated by choosing traditional roasting grinding powder(240?,15 min),baking oat flake grinding powder(140?,45 min)and control oat flour as experimental materials.The structure-activity relationship between spatial conformation and functional properties of oat protein is as follows:(1)There are 16 kinds of amino acids in five common cereals(oat,wheat,buckwheat,barley,and rice).Among them,oat has the highest total amino acid content(249.91 g/kg),followed by wheat,barley,buckwheat and rice.The contents of glutamic acid,phenylalanine,lysine and leucine in oat rank first among the five cereals.The average content of branched chain amino acids(BCAA)in oats was 29.58 g/kg,which was higher than that in other four cereals(21.17 g/kg).There were significant differences in BCAA content among different oat varieties.The high content of branched chain amino acids in oats should be paid attention in nutrition science.Comprehensive evaluation scores of amino acids in tested cereals(19 varieties)were as follows:oat>wheat>buckwheat>barley>rice.Six breeds of oats had better protein nutritional quality than other cereals.(2)The study on the structural and functional changes of oat protein isolation(OPI)by different heat treatments showed that compared with the control oat flour(C-OPI),the amino acid content of traditional roasted oat flour(R-OPI)and baking oat flake flour(F-OPI)decreased,the disordered structure content of oat protein isolation in secondary structure increased,the content of free sulfhydryl group and total sulfhydryl group in oat protein isolation in tertiary structure decreased,so the stability decreased.The ratio of free sulfhydryl group to total sulfhydryl group decreased,indicating less hydrophobic residues exposed and better solubility.Traditional roasting grinding powder has short heating time and decomposes to aggregate small molecular weight substances,while oat flake flour is heated for a long time to form macromolecular aggregates;the denaturation temperature of both was higher than that of the control oat flour,and oat flake protein isolate had lower viscosity and better digestibility.(3)The study on the structure and function of oat globulin by different heat treatments showed that the amino acid composition of three oat globulins was relatively balanced,and the content of amino acid in the control oat globulin was the highest.After heat treatment,the secondary and tertiary structure of oat globulin was destroyed and its stability decreased;the exposure of hydrophobic residues decreased,which is agreement with its increased solubility;the fluorescence intensity decreased,and the ultraviolet light intensity decreased.Some lower molecular subunits appeared in SDS-PAGE experiment.Compared with traditional roasting oat,oat flake globulin has more orderly structure and higher thermal stability and digestibility.After heat treatment,the structure and function of oat protein isolation and globulin are consistent.The traditional roasting grinding powder has higher heat treatment temperature and more amino acids loss.Oat flake flour retains more amino acids,and has good digestibility.