Study on Physical and Chemical Properties and Functional Characteristics of Isolated Proteins from Green Wheat Kernel

Albumin,globulin,prolamin and gluten from green wheat kernel were separated and purified by Osborne method. The content and purity of four proteins,the surface microstructure of four proteins,the basic components of the green wheat kernel,and the molecular weight,amino acid composition,physical and chemical properties and functional characteristics of the isolated protein were studied. The results showed that the relative contents of albumin,globulin,gliadin,glutenin and other proteins in the protein isolates of green wheat kernels were 60.1%,3.7%,2.9%,3.2%,30.1%,respectively,and the purity was 82.87%. The albumin in the isolated protein was ridge-like,with fine layers on the surface and small pores in the local area. The surface of the globulin was loose and the conformation was irregular. The surface of the gliadin was convex,composed of a compact multi-layered sheet. The surface of the gluten was smooth,with a porous sheet structure. The contents of protein,starch,fat,dietary fiber and ash of green wheat kernel were 11.21%,55.86%,1.15%,11.79%,and 1.30%,respectively. The SDS-PAGE gel electrophoresis of protein isolated from green wheat kernel contains 12 bands with molecular weights of 14.40,24.70,26.22,34.53,36.41,44.50,48.55,53.65,65.55,71.98,79.71,100.45 kDa,respectively. Glutamic acid was the highest,accounting for 38.3% of the total amino acid. The ratio of essential amino acids to total amino acids was 26.1%. The ratio of essential amino acids to non-essential amino acids was 29∶83.The protein had an isoelectric point of 5.0 and the lowest solubility at pH6. The water and the oil holding capacity was 1.02 g·g^-1 and 7.18 g·g^-1,respectively. When the concentration was 0.6%,the foaming was the best and the stability of the foam was the best. After the concentration of protein reached 0.8%,the emulsification and emulsification stability of the protein changed little,and had no significant difference(P>0.05). The foaming degree was the smallest at pH6,and the foam stability decreased first and then increased with the increasing of pH. The emulsification and the stability of emulsification was the worst at pH6. Based on the study of the physical and chemical properties,and functional properties of the protein isolated,the paper provided a new idea and direction for the development and industrialization of the new protein resources.