Isolation and Characterization of Acid Soluble Collagen from the Skin of African Catfish (Clarias gariepinus), Salmon (Salmo salar) and Baltic Cod (Gadus morhua)

Acid-soluble collagen (ASC) from the fish skin of African catfish (Clarias gariepinus), Salmon (Salmo salar) and Baltic cod (Gadus morhua) was extracted and characterized. The ASC extraction yield was 75%, 73% and 68%, respectively. The denaturation and melting temperatures of African catfish ASC (29.3°C and 100.0°C) were significantly higher than ASC of Salmon and Baltic cod (20.6°C and 90.5°C; 15.2°C and 86.7°C, respectively), assessed by differential scanning calorimetry. The SDS-PAGE profile showed that each of tested ASC was the type I collagen and consisted of two different α chains, α1 and α2, as well as a β component. The FTIR spectra of all collagens indicate that the overall their chemical compositions are quite similar. The fish skin collagen is easy to prepare and represents a possible resource for use on industrial scale.