Structure and stability of low molecular weight collagen peptide (prepared from white carp skin) -calcium complex

The low molecular weight (≤3 kDa) collagen peptide (CPLW) was prepared from white carp skin by intestinal simulation digested and ultrafiltration membranes. CPLW and calcium ions were combined to form a peptide-calcium complex (CPLW-Ca), and the structure and stability of the complex were characterized. The single factor optimization results indicated that the highest protein conversion rate and the maximum calcium binding ability were 60%, and 22.16 ± 0.55 mg/g, respectively. Structural analysis demonstrated that calcium ions bound to CPLW mainly via the formation of ionic bonds with carboxyl oxygen, hydroxyl oxygen and amino nitrogen atom of CPLW. The CD and particle size analyses showed that after CPLW was combined with calcium ions, the spatial structure was folded, which reduced the particle size with the formation of irregular nanoparticles. Stability analysis revealed that the calcium retention rate of the prepared CPLW-Ca remained substantially at 90% below 90 °C, and the calcium content of CPLW-Ca was significantly decreased under high acidic conditions. CPLW-Ca has the potential to be applied as an alternative for dietary calcium supplements.