Preparation And Characterisation Of Rabbit Skin Gelatin Films

Based on the problems such as gelatin from bovine and porcine is restricted and the characteristics of the fish gelatin film is relatively bad,this study adopt rabbit skin as raw material to preparation gelatin films.The effect of gelatin additions and glycerol concentrations on the properties and structure of rabbit skin gelatin films was studied.Then a comparative study was made on the functional characteristic and microstructure based on rabbit skin and porcine skin gelatin films.Finally explored the application of rabbit skin gelatin films in order to provide a theoretical basis for the industrial production and practical application of rabbit skin films.As the gelatin additions be the evaluation indexes,the paper had a series of performance tests found that the thickness and water vapor permeability increased with increasing the gelatin additions.Mechanical property results showed that rabbit skin gelatin films possessed the highest tensile strength value as the gelatin additions was 4g/100 m L,and possessed the highest elongation at break value as the gelatin additions was 3 g/100 m L.The subunit components results showed the band intensity of rabbit skin gelatin films was weak as the gelatin additions was 3 and 4 g/100 m L respectively which indicating that the two ? chains of the gelatin membrane could be partially degraded under this condition.However,the band intensity of rabbit skin gelatin films was strongest as the gelatin additions was 5 g/100 m L which indicating that the gelatin films system may produce more protein cross-link.FT-IR results showed that amide A band moved to higher wavenumber,which indicated that the gelatin films matrix was more of the reaction between gelatin molecules and formed unique network structure,and the stability of gelatin film was better.As the glycerol concentrations be the evaluation indexes,the paper had a series of performance tests found that the thickness and water vapor permeability increased with increasing the glycerol concentrations.Mechanical property results showed that the glycerol concentrations of 0% and 15% had no significant effect on the mechanical properties of gelatin membrane(P> 0.05).However,the tensile strength and elongation at break values increased significantly(P <0.05)with increasing the glycerolconcentration,and reached the maximum as the glycerol concentration was 30%.The subunit components results showed that there were no significant difference in the band strength of rabbit skin gelatin films with the glycerol concentration increased,indicating that the structure of gelatin films network were stable and the glycerol concentrations did not lead the gelatin protein degradation and aggregation.FT-IR results showed that amide A band and amide I band moved to lower and higher wavenumber respectively as increasing glycerol concentrations,which indicated that the glycerol molecules in gelatin matrix react with the N-H groups of the gelatin chain to form hydrogen bonds and the conformation of gelatin film network transformed from a stretched ?-sheet structure to the ordered ?-helix structure.The basic functional characteristics of rabbit skin and porcine skin gelatin films were compared by measuring the water vapor permeability,color,light transmission and mechanical properties,at the same time,the subunit components were studied to compared the microstructure of rabbit skin and porcine skin gelatin films.Results showed that the higher content of very hydrophobic amino acids in rabbit skin gelatin resulted in lower water vapor permeability,which indicated that rabbit skin gelatin based films possessed superior barrier properties than porcine skin gelatin films.The rabbit skin and porcine skin gelatin films were almost transparent and it will not affect the food appearance as food packaging films,and they both have excellent barrier properties against UV light which could prevent lipid oxidation reaction in the food system induced by UV light.Mechanical property results showed that the flexibility improved however the tensile strength reduced of the rabbit skin and porcine skin gelatin films with increasing the glycerol concentrations,while increasing the gelatin additions and glycerol concentrations simultaneously the tensile strength and the Young's modulus of rabbit skin and porcine skin gelatin films increased significantly.FT-IR spectra results showed that the main reaction in the rabbit skin gelatin films between rabbit gelatin molecules and glycerol molecules that led the gelatin network structure more stable and denser,which contribute to bounding glycerol and water molecules.However,the main reaction in the porcine skin gelatin films between porcine gelatin molecules themselves so that the porcine skin gelatin films possessed better rigidity.Moreover,the subunit components of the rabbit skin and porcine skin gelatin films would affect the mechanical properties,so the targeted gelatin films could be prepared according to the characteristics of the food in the application study.The results of surfaces and cross-sections microstructure showed that the surface of the two gelatinfilms was smooth and uniform,and the internal network structure was homogeneous.Rabbit skin gelatin films were used evaluate the freshness of grass carp and observed the quality changes of bacon in order to explored the application of the gelatin films.Evaluating the freshness of grass carp: The results showed that the total bacterial counts and total volatile basic nitrogen(TVB-N)values with prolonged storage,and the total bacterial counts and TVB-N values of PVC films and rabbit skin gelatin films were lower than those of control group,which may be related to the grass crap of control group contact with oxygen and moisture sufficiently in the environment.On the fourth day,the TVB-N values of PVC films,4g + 22% and 5g + 30% gelatin films group were23.86,21.83 and 22.44 mg/100 g respectively which exceeding the human body limit of20 mg/100 g.It is speculated that the shelf life of the fresh grass carp was three days by using the rabbit skin gelatin films and PVC films,which indicated that the rabbit skin gelatin films could delay the spoilage of the fish meat to some extent,and could carry short-term refrigerated preservation of grass carp.By measuring the change of color and texture properties found that the appearance of grass carp with rabbit skin gelatin films was similar to those with PVC films which indicated that the rabbit skin gelatin films may could replace the PVC films in the short-term refrigerated preservation.Observing the quality changes of bacon: By analyzing the changes of water content,peroxide value(POV)and thiobarbituric acid value(TBARS)had found that the water content of the control and rabbit skin gelatin films group decreased with prolonged storage and the water content were lower than others and the trend of decreasing was relatively stable of4 g + 22% gelatin films group.The POV values of control and rabbit skin gelatin films group were increased gradually in the storage process,and the POV values of gelatin films group were slightly than control group.In the storage process,the TBA values of rabbit skin gelatin films group showed an increasing trend,and the TBA values of gelatin films group were lower than control group which might be related to the insufficient contact between the bacon and the oxygen.Furthermore,the TBA values of4 g + 22 % gelatin films group were significantly lower than 4g + 30% and 5g + 30%gelatin films group,which might be related to low oxygen permeation rate of 4g + 22%gelatin films and the low moisture content of bacon in the 4g + 22% gelatin films.It was suggested that the rabbit skin gelatin films might can inhibit the oxidation of bacon to some extent in the storage process compared with the control group.In the three types of rabbit skin gelatin films,4g + 22% gelatin films could keep bacon lower water content and ensure the stability of bacon to a certain extent,so it might possess betterantioxidant properties.