Characterization of Turbot (Scophthalmus maximus) Skin and the Extracted Acid-Soluble Collagen

The biochemical composition of the turbot skin was investigated. The moisture level of the skin was found to be 51.4%. Based on dry matter content, there were relatively high protein (82.1%) and lipid (13.1%) concentrations in the turbot skin. Mineral element analysis revealed that the turbot skin had high Ca content (2069.0 mg kg(-1)), and the concentrations of toxic heavy metals Hg and Pb were less than 0.005 mg kg(-1), which indicates that the turbot skin is a safe resource for collagen production. The sodium do-decyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis showed that acid-soluble collagen (ASC) extracted from the turbot skin was type-I collagen. The imino acid content of the ASC was 241.6 per 1000 amino acids, which suggests a relatively high denaturation temperature. The Fourier transform infrared (FTIR) spectra of ASC reflected a highly stable structure, and the measured denaturation temperature of ASC was 29.5 degrees C, which is higher than those from many temperate fishes. ASC was the most soluble at pH 4.0, and when the pH values were below or above 4.0, the solubility decreased rapidly. The ASC exhibited a relatively high solubility when NaCl concentration was lower than 2%. These results show that turbo skin can be employed as a source for producing collagen with high quality.