Extraction And Properties Of Collagen From Grass Carp Skins And Characterization Of Films

Collagen possesses the typical triple helical structure, which gives it many excellent physical and chemical properties and special physiological funtions. In China, a large amount of waste, such as fish skin and scales is produced in grass carp and other freshwater fish processing industry, which is rich in collagen. In this paper, the combining process of collagen extracting from grass carp fish skin with acid and enzyme extraction method was studied. For pretreatment experiments, effects of some factors on the lipid and impurity protein removal from fish skin were studied and orthogonal optimization was carried out; The acid-soluble and pepside-soluble collagens (ASC and PSC) from grass carp skin were gotten. In addition, with the extration rate of collagen as index, this paper got the optimum conditons of combining extraction process with orthogonal test:using acetic acid of concentration of0.7mol/L as the leaching agent, solid-liquid ratio1:60, enzyme dosage selection of2000u/g, swelling time of12h, and stirring extraction time of4.5h.The some important properties of ASC and PSC were determinated and compared in this paper. Results showed that, the tendency of mean particle size with temperature of ASC was the same as PSC, and they both present the highest degree of aggregation at35℃, refferring to the retainment of re-fibrous nature; Determination of the ubbelohde viscometer showed the denaturation temperatures of ASC and PSC were29.2℃and28.7℃respectively. SDS-PAGE suggests that they are heterotrimeric collagens, both composed of two al chains and one a2chain; Uv scanning, CD spectroscopy and FT-IR investigation confirmed the existence of characteristic helical arrangements of both the ASC and PSC, indicating that they were type I collagen and not denatured.In addition, the collagen filming conditions were studied in this paper, and the result showed the best conditions were:0.5mol/L acetic acid as the solvent, the collagen concentration of20g/L, then the PP plate as filming dielectric, the film was natural drying at room temperature. The experiment of modifing collagen film through the post-crosslinking and blending with chitosan (Cs) and glycerol (CH) was performed. Choosing water absorption, transmittance and air permeability, etc. as indicators, some characteristics of these Col-Cs blending membranes and Col-Cs films with CH were examined to inspect the improvement. The best modification membrane could obtained with the blending proportion of Col and Cs of4:1and the CH addition amount of25%in blend films.