| In order to reduce the weight loss and extend shelf life of mangoes, this paper is carried out to the inhibition effects of chemical assistants like chitosan, Zn(NO3)2·6H2O, potassium sorbate and their combined bentonite on botryodiplodia theobromae and colletotrichun gloeosporioides. Using bentonite and chitosan as fillers, and polyvinyl alcohol (PVA) as matrix, fresh-keeping film of PVA blend chitosan and bentonite was prepared. Single factor analysis was applied to study the influence of the concentration of bentonite and chitosan on the properties of the film. These properties include physical and mechanical properties, water absorption, RH transmission, permeability and so on; the morphology characteristics of the film were tested through infrared spectroscopy and scanning electro microscope. Further, the film was applied in preservation of mangoes by packaging, and the change of mangoes quality during storage was studied by tracking a series of quality indexes. The main quality indexes include weight loss, respiration rate, decay index, soluble solid content, solid content, vitamin C content and so on. The results follow as:1. Chitosan, Zn(NO3)2·6H2O, potassium sorbate could effectively inhibit two strains pathogens of mangoes fruit. The inhibition was more stable and durable after the bacteriostatic agent combined bentonite; Amoung three agents, chitosan was most effective in inhibiting the radial mycelial growth of the two strains pathogens.2. The PVA film blend chitosan and bentonite demonstrates the best comprehensive properties when the content of the concentration of PVA solution, with bentonite and chitosan are 8%,15% and10%, respectively. The comprehensive propertyies include physical and mechanical properties, water absorption, RH transmission, permeability and so on.3. Infrared spectrum and SEM results show that bentonite and chitosan can be uniformly dispersed in the film. The three materials have good compatibility, and 1he film of surface was smooth and dense without air bubbles.4. Using the film and commercial PE film to package mangoes, respectively, the result show that they effectively reduce de decay index, the mass loss, inhibit the respiration of and extend the storage period of mango. Moreover prespervation effect of PVA film blend the chitosan and bentonite is better.5. Seal packaging mangoes by wrapping the PVA film blend chitosan and bentonite can form a confined space with a certain atmosphere, inhibit the physiological activity of mango, slow down the loss of nutrients in fruits, fresh mango play a role. In addition, chitosan against pathogens better inhibition mangoes blend films can inhibit the growth of pathogenic bacteria and their resistance to foreign bacteria infection, enhanced preservation effect. |
