Study On The Extraction,purifiation And Structure Analysis Of Collagen From Yak Bone

China is an animal husbandry country,livestock-raising industry and animal products processing technology develop rapidly,as a byproduct of meat processing industry,the yearly output of livestock and fowl bones are abundant and exist were not used as effectively as they might have been.High-value utilization of the bone and develop the deep processing of bone products are now an urgent research content.Comprehensive analysis of nutritional composition of four parts of Qinchuang cattle and Haibei yak bones,then extracted the bone collagen and analysis the structure of type I collagen from bone.The purpose of this paper is to offer theoretical basis and technical support in utilizing of the by-products.The results are as follows:1.Comprehensive analysis of nutritional composition of different bone,the results show that the content of moisture in different bone parts from various breeds were ranged from 12.7% to 29.8%,the ash content were 28.2%~47.0%,the protein content were 13.7%~23.2% and the content of fat were 10.7%~32.9%.The top-six abundant amino acids in bones are followed by Gly,Glu,Pro,Ala,Arg and Asp in all breeds.There are without short Chain fatty acids in bones,CLA content was ranged from 0.42 to 2.65 mg/g and the characteristic fatty acid of bovine bone were C18:1n9c,C16:0 and C18:0,and make up more than 80% of TFA,the content of fatty acids in yak bones were higher than Qinchuan cattle bones.The bones are rich in constants and trace elements which necessary for the human body,calcium to phosphorus ratio is ranged from 0.29:1 to 2.54:1.In a word,Haibei yak bones have higher protein,EAA and Hyp and its rib has the character of higher protein and lower fat content.Qinchuang cattle bones have higher ash,TAA and mineral content.2.To improve the extraction yield of collagen,used rib from Haibei yak as raw material,the extraction yield of collagen as an indicator to study the collagen extraction and purification process in two ways,and the condition of degrease,decalcification,salting-out and concentration of pepsin to be optimized at the same time.The optimum extraction process as follow: 0.1 mol/L NaOH is added into the yak bones to dislodge non-collagenous bone proteins.Then the residues were suspended in 10%(v/v)hexane solution to remove fat,used the distilled water to neutral and join 0.25 mol/L EDTA to decalcify.After being fully washed with cold distilled water,the residues were extracted with 0.5 mol/L acetic acid(or added 1.6% pepsin at same time)for extraction.Adjust pH and NaCl at a final concentration of 0.9 mol/L,then centrifuged at 10000 rmp for 30 min at 4?,and the precipitate was collected and redissolved in 0.5 mol/L acetic acid.The resultant solution was dialysed against 0.1 mol/L acetic acid,distilled water and freeze-dried in turn.Ultimately achieved acid-soluble collagen(ASC),pepsin-soluble collagen(PSC)and the extraction yield of collagen were 2.24% and 3.32% respectively.3.To identify collagen type of bovine bones,structure analysis of ASC and PSC was measured after purification.TAA content were 731.8 mg/g and 810.0 mg/g respectively,Gly content is the highest among 17 amino acids.UV spectrum analysis showed that maximum absorptions of ASC and PSC were 234 nm.In the FT-IR spectrum,the content of a-helix in PSC was double of ASC,?-sheet content were 29.5% and 41.2% severally,?-turn content were 3.8% and 25.4% respectively,there are no random coil in ASC and PSC.It was found that heat shrinkage temperature was 40.12 ? and 40.94 ? respectively.In the SDS-PAGE gel electrophoresis of ASC and PSC,there was a band near 200 kDa represents the ? band,and two bands near 110 kDa represents the ?1 and ?2 band respectively.Observed microscopic structure of collagen by scanning electron micrograph,found that a porous network structure and fibrous structure,but ASC is thin and distribute evenly while PSC is pockety.Based on above analysis,we conclude that haibei yak bone has the high content of protein,and the ASC and PSC from haibei yak bone had the complete triple helical structure and they are the typical type I collagen.