Physicochemical characterization of a zein prepared using a novel aqueous extraction technology and tensile properties of the zein film

Recently, our research team developed a novel aqueous extraction technology (AET) for preparing an a-zein enriched product from corn gluten meal without any organic solvents. This technology is conspicuously different from the conventional organic solvent extraction technology (OSET). The present study aimed to investigate the physicochemical and film-forming properties of the AET zein in comparison with those of the commercial zein by alcohol extraction. The results revealed that similar to the OSET zein, the AET zein was rich in proteins, especially alpha-zein. Meanwhile, electrophoretic pattern and amino acid composition were almost the same for both zeins, except that AET zein had trace quantities of beta-zein and protein hydrolysates, along with a higher proportion of Ile and lower proportion of His. The intrinsic differences probably contributed to a convergent pattern of the protein solubility in aqueous ethanol between AET zein and OSET zein, and a pronounced higher tensile strength/elongation of AET zein film. In addition, the removal effect of AET on some hazardous heavy metals brought in by raw materials, and no exogenous alcohols in the AET zein were confirmed by atomic absorption spectrophotometry and gas chromatography, respectively. The present findings suggest that AET zein has essential characteristics for use as an potential food ingredient or a pharmaceutical excipient, and the aqueous extraction technology thereby could be considered as an alternative strategy for zein production.