Optimization of Enzymatic Hydrolysis of Tilapia Scale Calcium Binding Peptides by Response Surface Methodology and Its Structural Characterization

In order to obtain the optimum enzyme hydrolysis conditions and chelating properties of tilapia scale calcium binding peptides, and provide basis for study of promoting calcium absorption of active material, in this study, the decalcified tilapia scales as raw material and calcium chelation activity as an index, papain was selected to optimize enzyme hydrolysis of the tilapia scales to obtain tilapia scale calcium binding peptides. The properties of the tilapia scale calcium binding peptides were characterized by amino acid analysis, ultraviolet-visible spectroscopy and fourier transform infrared spectroscopy. The optimal enzymatic hydrolysis conditions were as follows: the concentration of substrate 8%, time 2 h, enzyme to substrate ratio 0.3%, pH7 and temperature 60 ℃. Under these conditions, the calcium chelation activity of the enzymatic hydrolysate was (38.31±0.4) µg/mL. The results of characterization showed that, after chelating calcium, the contents of aspartic acid, glutamic acid, glycine, lysine, serine, cysteine and histidine in peptide-calcium chelate increased by 0.88%, 1.48%, 0.34%, 0.53%, 0.04%, 0.38% and 0.46%, respectively. The carboxyl oxygen and amino nitrogen groups in the calcium binding peptides participated in binding with calcium ions to form the tilapia scale peptide-calcium chelate. Tilapia scale calcium binding peptides has high calcium chelation activity, which lays a foundation for the production and application of calcium supplements.