Extraction and Characterisation of Collagen from the Skin of Golden Carp (Probarbus Jullieni), a Processing By-Product

Purpose Fish skin is a by-product generated during fish processing. Nowadays the farmed fish, including golden carp, has gained increasing interest from consumers. As a consequence, a huge amount of skin is generated. Those skins can serve as an important source of collagen, which can be used for several applications in food, pharmaceutical and biomedical industries. Additionally, collagen with high market value can increase the revenue for the farmer or fish processor. This study aimed to extract and characterise collagen from skin of golden carp. Methods Acid solubilised collagen (ASC) and pepsin solubilised collagen (PSC) were isolated from the skin of golden carp (Probarbus jullieni). Obtained collagens were subjected to SDS-PAGE and amino acid analysis. Structural integrity was determined via FTIR and CD spectra. DSC and solubility were also examined. Results Both ASC and PSC were characterised as type I collagen. Imino acid contents of ASC and PSC were 197 and 199 residues/1000 residues, respectively. Glycine constituted approximately 1/3 of total amino acid residues. No cysteine was present, indicating the absence of disulphide bonds. FTIR and CD spectra were almost similar between ASC and PSC. Thus pepsin hydrolysis had no marked effect on triple helical structure. ASC and PSC showed higher T-max values 36.28 and 37.87 degrees C, respectively, as compared to those from temperate and cold water fish collagens. The maximum solubility for both collagens was found at pH 3. Conclusion Skin of golden carp, a by-product from fish processing, could therefore serve as an alternative source of high quality collagen. Subsequently the economic value of fish skin could be maximised and disposal problem could be reduced.