Fabrication, characterization, and application of soluble oat-soybean protein and oat-pea protein composites prepared using an alkaline-thermal treatment

Recently, combining two or more proteins to create a novel protein blend with a higher nutritional value and better functional properties than the individual proteins has become popular. In this study, oat-soy protein (OSP) and oat-pea protein (OPP) blends were prepared by combining oat protein isolate (OPI) with either soy protein isolate (SPI) or pea protein (PP) using an alkaline-thermal treatment. This treatment involving incubating the protein mixtures at pH 12 and 55 °C for 1.5 h, followed by cooling to ambient temperature and neutralization to pH 7. The water-solubility of the resulting OSP (95.2 %) and OPP (96.2 %) blends was relatively high. SDS-PAGE analysis indicated that no new subunits were formed in the protein blends. Circular dichroism and fluorescence spectroscopy showed that the proteins in the blends had a more flexible structure than the original proteins and had undergone some protein-protein interactions. The mean diameters of the particles in the OSP and OPP dispersions were 283 and 612 nm, while their ζ-potentials were −34 and −38 mV, respectively. Scanning electron microscopy showed that the proteins in the blends were uniformly dispersed throughout the dispersions. The analysis of the chemical showed that the formed of composite proteins during alkaline-thermal treatment was driven by hydrophobic reactions in main role. Compared to the individual proteins, the protein blends exhibited better thermal stability, lower interfacial tension, higher surface hydrophobicity, stronger emulsification ability, and more low molecular weight fraction. Taken together, the results showed that a simple alkaline-thermal treatment can be used to improve the solubility and functionality of protein blends. • The protein composites were formed using an alkaline-thermal treatment. • The protein composites exhibited high water-solubility. • The protein composites had stronger emulsification ability than the individual.