Molecular and physical characteristics of squid (Todarodes pacificus) skin collagens and biological properties of their enzymatic hydrolysates

The physicochemical properties of squid skin collagens and biological activity of their enzymatic hydrolysates were determined to produce more value-added materials. The amino acid compositions of the inner and outer squid skin collagens were similar, but distinct from that of bovine tendon collagen in respect to the higher levels of aspartic acid, arginine, threonine, and serine, and of the lower levels of alanine, proline, and hydroxyproline. SDS-PAGE patterns suggested that squid skin collagen consisted of at least 2 different polypeptides (alpha 1 and alpha 2 chains) and their cross-linked chains. The molecular weights of alpha 1 and alpha 2 chains of bovine tendon collagens were higher than those of the corresponding alpha 1 and alpha 2 chains of squid skin collagens. The denaturation temperatures of inner and outer skin collagens were 27.1 and 27.3 degrees C, respectively, which were about 9 degrees C lower than that of bovine tendon collagen. Water holding capacities of inner and outer squid skin collagens were relatively similar, but were significantly greater than that of bovine tendon collagen. The maximum hydrolysis of squid skin collagens was obtained as follows: for outer skin collagen, enzyme concentration, 3.5%; hydrolysis time, 83 min; pH 7.0; hydrolysis temperature, 60 degrees C, whereas for inner skin collagen, enzyme concentration, 3.2%; hydrolysis time, 83 min; pH 7.0; hydrolysis temperature, 60 degrees C, whereas for inner skin collagen, enzyme concentration, 3.2%; hydrolysis time, 83 min; pH 7.0; hydrolysis temperature, 60 degrees C. The enzymatic hydrolysates of outer and inner skin collagens were separated by Sephacryl S-100 column, resulting in the production of 3 fractions (F1, F2, and F3). F3 fraction exhibited higher antioxidant, tyrosinase inhibitory, and antielastase activities than the other fractions.