Study On Preparation And Properties Of Fish Skin Gelatin And Composite Films

In the paper, the processing and properties of channel catfish skin gelatin were researched.The properties and preparation of composite films of fish skin gelatin and modified KGM were studied and analyzed.The research results are as follows:Through dualquadratic rotary regression orthogonal design experiment with four factors,the effects of hydrochloric acid concentration, the ratio of liquid to material, extraction temperature and extraction time on the yield were investigated,and a mathematical model describing the relationship between the yield and parameters was developed.The optimal extraction conditions were as follows: hydrochloric acid concentration 3.20%,the ratio of liquid to material 2.915, extraction temperature 64.5℃and extraction time 3.95h,and the yield was 11.55%.Under the optimal conditions,gelatin was analyzed as the proximate composition of 88.53% protein,10.04% moisture,0.62% lipid and 0.17% ash.The composition,structure and properties of fish skin gelatin were studied.In fish skin gelatin,there were large amount of glycine,proline and alanine,but none tryptophan and cysteine.SDS-PAGE electrophoresis showed that the molecular masses of the fish skin gelatin subunits were about 200kDa forβ,120kDa forα1 and 105kDa forα2,respectively.The gel strength,gelling and melting points of fish skin gelatin which were studied were 223g,15.7℃and 24.4℃respectively.The surface hydrophobicity of shin gelatin was determined by ANS,the results showed that the surface hydrophobicity of shin gelatin was small.The concentration of Cd,Pb,As,and Cr was analyzed by ICP-MS.The results showed that Cd was 0.04 mg/kg,Pb,As,and Cr were not found in the gelatin. Research had been carried out on oxidation modification to konjac glucomannan and the properties of composite films of fish skin gelatin and modified KGM.Through single factor and orthogonal experiments,the effects of reaction conditions on degree of substitution(DS) and viscosity(η) were investigated,and the optimum reaction conditions were obtained as follow:temperature 55℃,pH 11 and reaction time 3 hours.The results showed that the value ofηand DS were 10.13 Pa·s and 0.4926 respectively.The transparency of the ratio of fish skin gelatin and modified KGM 8:2 was very good. With increasing fish skin gelatin ratio in composite films,tensile strength increased and elongation to break decreased.The water vapor barrier properties of fish skin and modified KGM 8:2 was good by water vapor permeability. With the increasing of fish skin gelatin, the water vapor permeability decreased and the water vapor barrier properties increased.