Extraction Of Collagen And Preparation And Properties Of Collagen Porous Materials

Collagen is one of the important structural protein in animals bodies, account for about 80% of the total protein content. As a kind of natural polymer materials,collagen shows unique physical and chemical properties and biological activity such as good biocompatibility, biodegradable and low antigenicity, etc, when it compared with other biomass materials. As a result, it has been wide applied in different fields industries.In this paper, porcine skin was used as raw material and degreased in the first place. According to the principle of the dissolution in the similar material structure,using degreasing rate as an index to optimize the degreasing conditions with the methods of isopropyl alcohol and ethyl acetate mixed solvent to degreasing. And then,collagen with natural triple helical structure was obtained with pepsin enzyme extraction under acid condition. After that, three-dimensional pore structure of porous material was made with vacuum-freeze-dying technology, the physical and chemical properties of extracted collagen were characterized by these methods such as infrared spectrum, ultraviolet spectrum, isoelectric point, denaturation temperature and intinsic viscosity, etc. In the end, collagen porous materials were cross-linked by genipin that was new biological crosslinking agent with different concentrations, and the pore diameter, mechanical strength and water uptaking and water retention capacities of collagen porous materials were characterized by different methods before and after crosslinking, respectively. The main research results are as fellows:1 、 Through the single factor experiment to determine skimmed temperature,skimmed time, solid-liquid ratio and volume ratio of isopropyl alcohol and ethyl acetate on the degreasing rate. And then selected skimmed temperature(A), skimmed time(B) and solid-liquid ratio(C) as the main influencing factors on the basis of single factor experiment result again. Using degreasing rate as an index, orthogonal optimization method L9(34) was applied to optimize degreasing process for pigskin,the best degreasing process as follows: skimmed temperature was 35 ℃, skimmed time was 4h and feed-liquid ratio was 1:4, the degreasing rate can reach 90.32% inthis process conditions.2、Collagen was extracted from porcine skin with the combination method of acetic acid and pepsin. Through the single factor experiment to determine enzyme dosage, enzymolysis temperature and enzymolysis time on collagen extraction yield.And then selected enzyme dosage(A), enzymolysis temperature(B) and enzymolysis time(C) as the main influencing factors on the basis of single factor experiment result again. Using extraction yield of collagen as an index, orthogonal optimization method L9(34) was applied to optimize the optimal extraction process, the best extraction process as follows: the pigskin was enzymolysis 60 h under the condition of enzymatic hydrolysis temperature of 35℃ and the content of pepsin was 15.0mg/g, the yield of collagen can reach 18.87% under the technological conditions of extraction. The thermal denature temperature, intrinsic viscosity, the physical and chemical properties such as isoelectric point of the extract were characterized by ultraviolet spectrum,infrared spectrum and viscosity analysis method. The results indicated that the experiment extractive was type I collagen of pigskin.3、Genipin was used as crosslinking agent in this experiment. Through the single factor experiment to determine genipin concentration, crosslinking time, crosslinking temperature and pH value of the solution on the crosslinking degree. And then selected genipin concentration(A), crosslinking time(B) and crosslinking temperature(C) as the main influencing factors on the basis of single factor experiment result again. Using colour and crosslinking degree of collagen materials as an index, orthogonal optimization method L9(34) was applied to optimize the optimal crosslinking process, the best extraction process as follows: under the condition of crosslinking temperature was 35℃ and genipin concentration was 0.05%, collagen porous materials was crosslinked 24 h, the crosslinking degree was 30.6% under this process.