Abstract: This study aimed to reduce the waste of wheat germ resource and simultaneously achieve its value-added utilization for the purpose of solving the problem of calcium deficiency in some populations. Wheat germ protein hydrolysates was prepared by enzymatic hydrolysis using alkaline protease and then chelated with calcium ions to obtain calcium-chelating polypeptides. One-factor-at-a-time and orthogonal array experiments were devised to investigate the influence of reaction temperature, molar ratio between polypeptides and calcium ions, reaction time and pH on the chelation efficiency. The optimal conditions that provided maximum chelation efficiency (86.21%) were determined as follows: reaction at 65 ℃ and pH 9.5 for 60 min with a molar ratio of polypeptide to calcium of 3:1. Infrared spectroscopic analysis confirmed the coordination reaction between calcium and carboxyl/amino groups in the polypeptides. Circular dichroism spectra indicated that the calcium-chelating polypeptides lost their disordered secondary structure and formed compact and ordered conformations compared to the control group. Scanning electron microscopy observation con?rmed significant aggregation of calcium-chelating polypeptides.

Key words: wheat germ polypeptides, chelated calcium, structural characterization