| The effects of enzymolysis time and acidic deamidation modification on the calcium-binding capacity of phytate degraded soybean protein isolate peptide were studied, and the structural and nutritional properties of peptide-calcium chelate were characterized. The results showed that when enzymolysis time was 240 min, the amount of bound calcium was higher (57.85 mg/g) and the chelate yield was 28.43%. After acidic deamidation, the amount of bound calcium and chelate yield increased to 75.37 mg/g and 3455% respectively. Amino acid analysis demonstrated that acidic amino acid made the most contribution to chelation. The results of Mr distribution experiment indicated that peptide with Mr≥1 000 showed a better chelation effect with a higher chelate yield, while peptides with Mr≤500 were the main peptides when making chelation with high amount of bound calcium. Fourier transform infrared spectra expressed that oxygen atom on the carboxyl group and nitrogen atom on the amino group were primary coordination atoms, while peptide structure changed a lot. In vitro digestion and absorption simulation experiment indicated that peptide-calcium chelate had a better tolerance to pepsin and pancreatin, and the Mr of the peptide almost had no change after digestion, with calcium retention rate about 87% and bioavailability up to 81.81%. |
