| Collagen and its derivatives are widely used in the fields of food,cosmetics and biomedical materials pharmaceuticals,and have a wide market prospect.In recent years,due to the increasing incidences of classical swine fever,avian flu,bovine spongiform encephalopathy and other infectious diseases,collagen extraction of terrestrial animals has raised concerns about its safety.Therefore,fish collagen and its derivatives have become the hot spots in research and have great market prospects.Acid-soluble collagen?ASC?and enzyme-soluble collagen?PSC?were extracted from the skin of Dasyatis akajei,meanwhile the characteristics of the collagen were studied.On this basis,using the collagen as raw material,the nanofiber membrane was prepared by electrospinning to solve the technical bottleneck of poor thermal stability and poor mechanical.In addition,Dasyatis akajei skin was used as raw materials,which using response surface methodology to prepare collagen peptides,and then identified physicochemical properties in this study.The main results are as follows:The yield of PSC was found to be?37.18±0.71?%,which was higher than ASC?33.95±0.70?%,and the analysis of SDS-PAGE,UV,FTIR,CD,XRD showed that they were typical I collagen with a natural three helix structure.The thermal stability results show that the Td of ASC and PSC were 23.82?and 24.46?,respectively,and the Ts were 85.25?and 95.46?,respectively.The thermal stability of PSC was better than ASC.The rheological properties of collagen showed that the viscosity of ASC and PSC solutions decreased with increasing shear frequency at different temperatures and concentrations,which showed that a non-Newtonian pseudoplastic flow behavior.Functional properties showed that PSC has better foaming,emulsifying and water holding capacity compared with ASC,which showed that PSC is more suitable for food,cosmetics than ASC.The fat absorption capacity of ASC was better than PSC,indicating that the hydrophobic amino acid in ASC was higher than that of PSC,which is more suitable for the processing of candy and meat.The collagen pullulan nanofiber membrane was prepared by electrospinning technique,and the average diameter of the nanofiber membrane samples were less than 350 nm.With the content of pullulan increasing,the diameter of the samples decreased from?292.96±51.38?nm to?242.16±35.65?nm,indicating that the interaction between collagen and pullulan produced hydrogen bonds.FTIR analysis demonstrated that with the increasing of pullulan content,the interaction between collagen molecules and pullulan molecules in sample produces red-shifted hydrogen bonds and blue-shifted hydrogen bonds.The ratio of the amide III of the collagen molecule to the absorption intensity of 1450 cm-1 in sample was above 0.5,indicating that the collagen molecule in sample still maintained the three helix structure.Thermogravimetric analysis showed that with the increasing of pullulan content,the degradation temperature of the sample increased from302.56?to 319.20?.The tensile strength increased from 17.17 MPa to 31.33 MPa,and the Young's modulus increased from 8.15 MPa to 15.02 MPa.Hence,collagen pullulan nanofiber membrane could effectively improve the thermal stability and mechanical properties of collagen.The optimal hydrolysis parameters were determined by enzymolysis technol-ogy which is optimized by response surface methodology,and the best parameters are as follows:pH 5.00;hydrolysis temperature 44.5?;hydrolysis time 3.7 h;enzyme concentration 6.00 g/L.The experimental degree of hydrolysis under optimal conditions were?20.47±0.11?%,which agrees with the predicated value of 21.1793%.Here,180 peptides were identified from the sample by liquid chromatography-tandem mass spectrometry,and their molecular weights ranged from707.40 Da to 2021.04 Da.99.44%of the peptides have a molecular weight of less than 2000 Da which can be absorbed easily into the human.Of these peptides,66.11%were hydrophilic peptides,and 33.89%were hydrophobic.Results indicate that collagen peptides have good solubility.Functional characteristics analysis showed that the peptides have good foaming properties,emulsifying properties,water holding capacity and fat absorption capacity,which can be used in the food and cosmetics industry.This study completed the preparation technology,structure identification,physicochemical properties and functional properties of collagen and its derivatives of Dasyatis akajei skin,Collagen and collagen peptides were developed to turn waste into treasure and realize high-value utilization of low-value marine living resources.With collagen as raw material and without cross-linking agent,collagen pullulan nanofiber membrane with high safety was prepared by electrospinning technology.The nanofiber membrane has good thermal stability and mechanical properties.Expanding the application scope of collagen to provide new ideas for the industrial application of collagen. |
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