Studies On Extracting Collagen From Pig Skin With Enzyme

Collagen is the most common protein family in animal bodies. It is the majorstructural protein of connective tissues such as skin, tendon cartilage and bone andits amino acid composition and structure is unique. The industrial use of collagen ismore and more common and has been expanded and now includes foods, cosmeticsand biomedical materials. Each year, over 200,000 tons of animal-derived collagen isused. Most of the collagen is derived primarily from bovine by-products. There isactive discussion of its role in BSE (bovine spongiform encephalopathy). So, it isnecessary to seek alternative sources of collagen. Pig skin is thought as useless inpork processing. Only little of it is used in tannery, most of it has the potential to beused. In this paper, the proper method has been used to extract collagen from pigskin. A new process has been developped to prepare collagen. The structure andcharacterization of collagen from pig skin were also measured, it will offer usefulguide for the product's use. Early in the experiment, acid was used to extract collagen from pig skin. Wefound that the yield of collagen was low, so this method was not suitable forpreparing collagen. We determined to prepare collagen with proteinase. A new process was determined to extract collagen from pig skin, whichincluded the following steps: (a) Pig skin was washed, depilated and cut up. Then, itwas dipped in 10% NaCl solution to remove soluble inpurity, and then degreasedwith lipase; (b) Collagen was extracted with proteinase in 0.5mol/L acetic acidsolution; (c) Salt out collagen by adding NaCl directly into the collagen solution; (d)The precipitate was dissolved in acetic acid solution, then, purified by ultra filtration, III北京化工大学硕士学位论文 Abstractand then obtained product by freeze drying. The main influencing factors in the process were optimized by single factordesign and orthogonal experiment. In the yield of collagen as a remark, pepsin wasmore efficient than other enzymes; the best conditions of preparation with pepsinwere: m(pig skin): v(0.5mol/L acetic acid)=1:10, 4℃,m(pepsin):m(pig skin)=1:50,72hours; the best conditions of salt-out were: 4℃, 4mol/L, 36hours. Using thisoptimization process, the yield of collagen was 16% (on a dry weight basis) and thepurity of collagen was 96.3%. The cost was 240.3yuan/kg to prepare collagen usingthis optimized process. The structure and characteristic of pig skin collagen were also measured,which indicated that collagen extracting from pig skin with pepsin had maintained itsnature structure, and had many special characters, it could not only be used in foodsand cosmetics, but also be used in biomedical matericals and other high extra valuefields.