Optimised condition for preparing sea cucumber ovum hydrolysate–calcium complex and its structural analysis

This study aimed to determine optimum preparation conditions of sea cucumber ovum hydrolysates–calcium (SCOHs–Ca) complexes by Box–Behnken design and further elucidate their microstructure characteristics using Fourier transform infrared spectroscopy, scanning electron microscope, atomic force microscopy and dynamic light scattering. The predicted calcium‐chelating capacity under the optimum conditions of the process variables was very close to the experimental value (53.45 ± 0.29 mg g⁻¹) determined in the batch experiment. Results demonstrated that the calcium bind to the SCOHs to form the SCOHs–Ca complexes primarily via interactions with carboxyl oxygen and amino nitrogen atoms. The prepared SCOHs–Ca complexes formed compact nanoparticles and exhibited a fold and porous network structure. These changes could be attributed to the interaction between peptides and calcium ions. Our findings provide a theoretical basis for the development of new calcium preparations as well as the high‐value utilisation of sea cucumber by‐products.