Study On Structure Characteristics And Film-forming Properties Of Sheep Bones Collagen

Sheep bones are the main by-products after slaughtering.Sheep bones are rich in collagen,and highly nutritious.However,the structure and properties of sheep bones collagen were not well characterized so far,and the degree of intensive processing of sheep bones was relatively low now,which led to serious wasting of resources.To improve the the added value and comprehensive utilization rate of sheep bones,this study was conducted to extract acid soluble collagen?ASC?and pepsin soluble collagen?PSC?from ovine bones.The characterization of structure and physicochemical properties of sheep bones collagen were analyzed in this study.The responses of collagen to temperature were also analyzed by peak fitting and two-dimensional infrared correlation analysis.Further,the study prepared the collagen/chitosan blend film and characterize its film-forming properties and structures.The applications of collagen/chitosan blend films were studies by packaging the cooking oil,dry meat and seasoner,in order to provide ideas for utilization of sheep bones collagen.Main conclusions are as follows:The structure characteristics,thermal denaturation and electrochemical properties of sheep bones collagen were analyzed.The purities of sheep bones collagens were verified by the content of hydroxyproline,UV spectrum and 1-DE.Ovine bones collagen were type I collagen identified by LC-MS/MS.The results of FTIR spectra and CD spectra analysis testified the existence of triple superhelical structure in both ASC and PSC,showing pepsin did not disrupt the triple helical structure of ovine bones collagen.Higher imino acid contents and level of hydroxylation were responsible for higher thermal denaturation temperatures of ovine bones collagen compared to fish collagens.ASC had a lower isoelectric point than PSC due to the higher content of acidic amino acids.The results of peak fitting of infrared spectrum showed the rules of structure changes of collagen are almost similar during the dehydration and aqueous heating,however,collagen was more sensitive to temperature in water aqueous.With the increase of temperature,the shift of the main absorption bands and the unwinding of triple helix occurred.The content of?-helix gradually reduce,and the content of random coil increased,showing the molecular structure gradually stretch and disorder.Two-dimensional infrared scorrelation spectroscopy indicated the response order of collagen molecules to temperature was different during the dehydration and aqueous heating.When collagen were treated during the dehydration heating,CH₃ of proline responded to temperature first.However,N-H bending vibration responded first in aqueous.The result showed the addition of chitosan could significantly increase the thickness and the tensile strength of pure collagen films,but decreased the elongation at break.The addition of chitosan increased the transparent value,but brought sightly yellowness.Light barrier property of blend films don't increase markly in the ultraviolet region,but decreased significantly in the visible light region.BC-CS films have better light barrier property than SG-CS films.Compared to pure collagen film,blend films exhibited increased water vapor permeability and thermalstability,but decreased water solubility.FTIR results showed intermolecular hydrogen bonds formed between collagen and chitosan.The BC-CS films were more homogeneous and smoother than pure collagen film.The collagen/chitosan blend films were applied to package the cooking oil,dry meat and seasoner.Compared to pure collagen film,the collagen/chitosan blend films could reach better the effect of molding.The addition of chitosan don't change oxygen permeability of pure collagen film,and increased the antimicrobial property,but increased water vapor permeability.Therefore,collagen-chitosan blend film can be used as food packaging,but its application in the dried food and storage condition needs further be studied.