ASC was extracted as per the method of Nagai and Suzuki (2000) with slight modification. All processes were carried out at 4 C with continuous stirring. The pretreated skins were defatted with 10% butyl alcohol with a solid/solvent ratio of 1:10 (w/v) for 48 h and the solvent was changed every 8 h. Defatted skin was washed with cold water (5–8 C), followed by soaking in
0.5 M acetic acid with a solid/solvent ratio of 1:15 (w/v) for 24 h. The mixture was filtered through two layers of cheese cloth and the residue was re-extracted under the same conditions. Both filtrates were combined. The collagen was precipitated by adding