Preparation Of Hydrolyzed Artificial Collagen Casings Using Defective Natural Casing

Natural casing is a kind of film that use pig, cattle or sheep's gut which has been cleaning, removing residual tissue and deeping processing. This is a flexible, mechanical strength, translucent film. In the long development course, natural casing plays important role in the enema foods. It has advantages of safety and environmenta, green and tough. As people's tastes demand is higher and higher, natural casing has shortage, low efficiency and high defective rate, etc. Natural casing already can't satisfy people's requirements. But using the pigs and cattle leather as raw material,taste is not the same as natural casing.So recycling this part of defective natural casing to produce edible casing film has important practical significance and commercial value.This article studied the possibility and mechanism to use the homemade single screw extruder to produce tubular films through defective natural casing. Through natural casing pretreatment, grinding, extrusion, film forming, finalize the design, crosslinking, drying and other steps prepare into artificial casing film. Through the research we found that the choice of the acid and alkali, the processing time in the natural casing pretreatment process and mechanical processing, heat, acid, enzyme in the process of the preparation of collagen regiment have great influence in the properties of the film. At the same time with different molecular weight range of protein film-forming effect. Investigated by defect casing as the raw material preparation of collagen, gelatin and collagen and the feasibility of hydrolyzed collagen film. Also during the preparation of gelatin film was investigated by adding different content of plasticizer,crosslinking agent and different membrane liquid pH and change the influence of different crosslinking temperature on membrane mechanical properties to further explore the mechanism of film forming. At the same time by scanning electron microscope(SEM), infrared spectrum(FT-IR)on collagen casing and crosslinked under the surface of membrane and gelatin film. The results show, collagen of preparation process, the molecular weight, the greater the various properties of film forming about close to natural casing. Plasticizer mainly fill in membrane pore have the effect of increased membrane tenacity, crosslinking agent and protein chain on tintramolecular or intermolecular reaction, and transform the machinery and mechanical properties of the membrane, pH and crosslinking temperature casting solution is also affect membrane internal crosslinking reaction, in turn, affects the performance of the membrane.For preparation of artificial collagen casing in the process of solidification of plasticizer, cross-linking agent, solution pH, and the processing temperature conditions on the casing in the process of crosslinking film mechanical properties after the film, film WVP,swelling properties, shrinkage performance. The results showed that with the increasing of the plasticizer glycerin, the tensile strength of membrane TS and swelling rate were decreased, and the breaking elongation E and WVP is higher.Glutaraldehyde as crosslinking agent, membrane permeability and swelling performance decrease rapidly, while mechanical properties change much. Through the optimization of preparation conditions: in the coagulation bath, plasticizer glycerin is 6wt%, crosslinking agent glutaraldehyde is 0.5wt%, pH is 10,crosslinking temperature 50? .Processed casing tensile strength up to 1500 MPa·m-1, breaking elongation rate was 15%, the moisture permeability (WVP) 0.053((g m)/(m2·h· kPa)), swelling degree 107.4%.