Isolation and characterization of collagen extracted from channel catfish (Ictalurus punctatus) skin

•Collagen from channel catfish skin was isolated and characterized.•Collagen extraction methods were improved for practical use.•Kinetic analysis was performed for collagen extraction processing.•Gel strength of collagen extracted by different methods were compared.

Channel catfish skin is a by-product from catfish fillet production. Collagens were extracted from catfish skins by: (1) acid; (2) homogenization-aided; and (3) pepsin-aided extraction methods. Kinetic analysis of extraction was performed. SDS-PAGE was carried out for all collagens extracted under different conditions. Protein solubility, zeta potential, circular dichroism and gel strength of the collagen extracted by three methods were studied to determine optimal extraction conditions. Protein recovery rate from minced skins extracted with pH 2.4 HCl containing 23.6 KU/g pepsin was the highest (64.19%). SDS-PAGE showed that collagens extracted with different methods had different proteins ratio patterns, even though the molecular mass of collagen subunits were similar, 123 and 113 KDa for α1 and α2 chains, 226 KDa for β chain and 338.5 KDa for γ chain, respectively. Channel catfish skin collagens were typical type I collagens and could have applications in food, medical and cosmetic industries.