Preparation Process Optimization of Soy Peptides-Zinc Chelate and Its Structural Characterization

In this paper, soy protein isolate was hydrolyzed by alcalase to prepare soy peptides, and the peptides were chelated with ZnCl₂ to prepare peptides-zinc chelate. Using zinc-chelating capacity as an indicator, the combination of single factor experiments and orthogonal experiments was used to optimize the chelation process. The optimal condition was determined as zinc concentration of 450 μmol/L at 75℃ and pH5.5.The zinc-chelating capacity of soy peptides was (26.96±1.22) mg/g in the optimal condition. The results of ultra-violet spectroscopy and Fourier transform infrared spectra synthetically indicated that zinc could be binding by carboxyl and amino group in peptides, thus forming soy peptides-zinc chelate. The results of fluorescence spectroscopy, scanning electron microscope and zeta potential showed that intramolecular and intermolecular folding and aggregation occurred during the formation of the chelation. The soypetides-zinc chelate would provide a new idea and theoretical basis for the development of new zinc supplements.