Isolation Of Collagen And Prepration Of Edible Film From Skin Of Channel Catfish

In China aquatic resources are rich, these resources have been utilized for machining processing. A huge amount of fish skin and tissues is discarded. However, abundant collagen contained in fisheries waste has varied application areas, including food, pharmaceutical, cosmetic and biomedical materials. Gelatin as a kind of collagen modified product, is a thermally reversible mixture, it has good film-forming performance. Edible film is composed of natural edible substance(such as proteins, polysaccharides, lipids, etc.) and supplemented by edible plasticizer, cross-linking agent.Through intermolecular interactions the film is formed. More and more researchers pay attention to edible film. Edible film has the function that prevent gas and solute migration, it guarantee the quality of the food and prolong the shelf life. Compared with gelatin of mammals, gelatin of aquatic animal has low thermal stability, weak mechanical strength and the water vapor barrier effect, which limits the application of aquatic animal gelatin edible film. Through a lot of research by scholars, adding natural compounds in the aquatic animal gelatin can improve the mechanical strength and water resistance of the film. Chitosan is a rich source of shellfish shell extract. Amino and carboxyl in the chitosan molecules with carboxyl and hydroxyl in gelatin molecules is easy to produce hydrogen bond, ionic bond and so on. Chitosan- Gelatin edible film can effectively improve its mechanical properties and thermal stability and chitosan itself is also a good antibacterial material.This paper with channel catfish as the materials, studied the preparation, formulation and performance factors of single gelatin film and chitosan-gelatin film. Through measuring the indicators, using the orthogonal and the response surface method to get the best preparation. Finally making preservation experiment of Swimming crab and strawberry. The results as following:1. This study in Chapter 3 has applied orthogonal method to optimize the condition for single gelatin film preparation craft. With gelatin as the membrane material, glycerol as plasticizer, transglutaminase as a cross-linking agent. The optimumm preparation condition was that the gelatin concentration was 6%, the glycerol concentration was 3%, adding 0.3% transglutaminase and dring at the temperature 70℃. And through the analysis of the influence factors, glycerin and enzyme content has the greatest influence on the performance of film, relatively gelatin concentration and heat treatment temperature on the film performance impact is small.2. This study in Chapter 4 has applied model to optimize the condition for gelatinchitosan film preparation craft to get the maximum stretch strength. The result of variance analysis indicated the goodness of fit index is fairly good. The optimum condition was gelatin/chitosan ratio of 6:4, heating temperature reached 70℃,glyceol 10%.To get the maximum tensile stiength 24.2Mpa. Response surface methodology was effective to optimize the gelatin/chitosan ratio, heating temperature and glyceol concetration. The study provided a theoretical foundation of large-scale preparation of geletin-chitosan film.It not only improved the existing edible film that has poor mechanical strength, but also enhanced the preservation of properities due to the adding of chitosan.3. This study in Chapter 5, using the geltin-chitosan edible film to carry out preservation experiment of swimming crab and strawberry. The results shown that,edible film on swimming crab and strawberry have better effect than the blank group. The TVB-N of swimming crab with gelatin-chitosan film was in a fresh range within a week. The sensory quality of swimming crab was also well kept. The strawberry with gelatin-chitosan can reduce water loss rate and corruption index, maintain its overall sensory quality and extend the shelf life of strawberries.