| Recent years, edible film have already replaced or reduced some of the use of plastic film,reduced or eliminated environmental pollution. It is a great development prospects for the green packaging materials. Now days, people made many kind of compound films that are made by one or more natural edible film-forming materials and have good mechanical intensity and barrier properties. It can be used in food packaging to prevent foods from spoilage.This paper with gelatin and chitosan as film materials, studied the gelatin film and the preparation technology, formulation and performance factors of it's compound film by the numbers, thus prepared the single gelatin film and gelatin-chitosan compound film. Respectively adopt the cup method, tensile tests and colorimetry to test the water vapor permeability (WVP), tensile strength and elongation at break and light transmittance of the compound film. Using the response surface method obtained the optimum technology and formula of the gelatin film and gelatin-chitosan compound film.Firstly, discusses the single film of the preparation process, with gelatin as the membrane material, glycerol as plasticizer, transglutaminase as a cross-linking agent. Through the single-factor and orthogonal test, the edible film ingredients can be optimized. After degassing, drying, softening and uncovering, the edible compound film can be prepared. The results showed that the concentration of gelatin is 6%, the glycerol concentration is 3%, the amount of transglutaminase added 0.3%, pH6.5; the edible film can gain the best performance.Secondly, the subject discussed the preparation of the gelatin-chitosan compound film, studied that make the 6%gelatin,1.5%chitosan according to a certain percentage to prepared the edible compound film. A study on the effects of glycerol doses on film's properties was done. With increased glycerol doses, the tensile strength decreased while the elongation rate increased. And WVP of the film lowered at first and then went up. There was little change on the transparency. So a suitable glycerol addition for making the compound film was determined to be 4%(g/g);the study of cross-linking agent transglutaminase on the compound film, the results showed that when the enzyme dose at 0.3%(total dry gelatin), the film's tensile strength and elongation at break optimal, the other performance is also good; the chapter also examined the pH and other factors on the compound film. This chapter use response surface experimental design analysis, the conclusion is that,6%gelatin (w/w), glycerol 3.26%, transglutaminase 0.40%to obtain the compound film tensile strength 22.8168, elongation at break rate of 167.166. The process not only improved the defects of existing edible film that has poor mechanical strength, having included the chitosan, also enhanced the preservation of properties of edible films.Finally the thesis researched glatin-chitosan edible compound film preservation, with 6%gelatin,1.5%chitosan is made by the best ratio for preservatives on fresh meat and fresh-cut grapes for coating preservation, results shown that, coating on fresh meat and fresh-cut grapes have played a better effect on products, the meat at 4℃deterioration does not occur within 20 days, while the fresh-cut grapes at room temperature (30℃, in summer) is still 10 days maintain fresh state.The results for edible film not only in the field of food and other field provide important reference data applications, but also after with the gelatin and chitosan compound and cross-linked by the transglutaminase modified to enrich the study of compound edible film theory, with more great theoretical significance and high practical value.
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