The Isolation And Purification Of Collagen From Fish Skin

Collagen is a major structural protein that helps support internal organs and skin, and protects bodies. It is the major fibrous element of skin, bone, cartilage, teeth, tendon and blood vessels, and comprises a family of fibrous proteins present in all multicellular organisms. With a high content of glycine, proline and hydroxyproline, collagen and its is widely used in medical treatments, health care, food processing, cosmetics and other industries.The outbreak of bovine spongiform encephalopathy (BSE) has resulted in anxiety among users of collagen preparations from domestic animals. In order to develop a new collagen source and rationally utilize up fish offal during mechanical processing of freshwater fish,this paper has studied the isolation and utilization of collagen from skins of the freshwater fish-grass carp (Clenopharyngodon idellus).The study aimed at exploring feasibility and influencing factors of a simplified method based on alkaline hydrolysis and made a comparison between the assay methods based on alkaline hydrolysis and acid hydrolysis at the same time .The best experimental project was obtained by the orthogonal experiment.The method of the alkaline hydrolysis was determined by tests of reappearance, stability and recovery rate and was compared with the acid hydrolysis method.The investigation has studied the isolation and purification of fish skins by acetic acid.Fish skins of grass carp were stirred with 5 % NaCl solution at a ratio of material to solvent of 1:10 (W/V) at about 4℃for 24h to remove a part of soluble non-collagenous protein. The extract was purified further by salting out in best concentration of NaCl and dialyzing, and purity of the collagenous solution was 93.00%. It was found that the collagen recovery rates of fish skin was about 82.15%.SDS-PAGE,intrinsic viscosity and thermal stability of collagen preparations were determined. Collagen isolated from grass carp was characterized as type I collagen, with the structure of [αl(I)]2α2(I).Intrinsic viscosity was 14.3dl/g and Denaruration temperature was 28.8℃.