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

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 alpha(1) and alpha(2) chains, 226 KDa for beta chain and 338.5 KDa for gamma chain, respectively. Channel catfish skin collagens were typical type I collagens and could have applications in food, medical and cosmetic industries.