Prepration Of Nano Oxide/Chitosan Composite Antibacterial Coatings And Its Application In Preservation Of Fish Balls

The nanometer oxide/chitosan composite coatings were prepared by blending method based on chitosan coating matrix after adding the modified nanometer antibacterial material in acidic solution of chitosan.The effects of the nanometer antibacterial material on the properties of the composite coatings were researched using the mechanical properties,gas permeabilities and transparency as physicochemical indexes.Meanwhile,the coatings were characterised by SEM,TEM,XRD,FT-IR,et al.The preservation properties of the ZnO/TiO2/SiOx-chitosan composite coatings to Silver Carp fish balls and the preservation properties of the Ag/ZnO-chitosan composite coatings to Hairtail fish balls were researched.And then,the antibacterial function path and mechanism of the Ag/ZnO-chitosan composite coating to predominance putrefying bacteria of aquatic products were indicated with Shewanella putrefaciens and Pseudomonas aeruginosa as the samples.1.The effects of nanometer magnesium compounds with different morphologies on the properties of the composited chitosan coatings were investigated.The results show that the crystal forms of chitosan are changed due to the active group on the surface of magnesium compounds.Mg2(OH)3Cl nanosheets and nano-MgO particles is dispersed uniformly in the coatings,and are adsorbed and bonded adequately with chitosan.So the microstructures of the coatings are improved and physicochemical properties of the coatings are increased.However,MgO nanorods and nano-MgO pellets are reunited in the coatings,resulting in formation of gap even crack in the chitosan coatings,so the physicochemical properties of the coatings are reduced.2.The in-situ SiOx-chitosan composite coatings were modified by the nanometer ZnO/TiO2 composite powders,which were modified with sodium hexametaphosphate or sodium dodecyl benzene sulfonic acid.And then,the effects of nanomaterials modification on physicochemical properties and microstructures of the coatings were researched.The results show that there are most of ydroxyl groups and hydrophilic on the surface of nanometer ZnO/TiO2 composite powders after modified with sodium hexametaphosphate or sodium dodecyl benzene sulfonic acid.So the nanometer ZnO/TiO2 composite powders will be bonded with hydrogen bonding with chitosan easyly,and then improve the physicochemical properties of the in-situ SiOx-chitosan composite coatings.The results of preservation of chitosan composite coatings to the Silver Carp fish balls at 4? show that the growth of microorganisms and the oxidation decomposition of protein and lipid of the Silver Carp fish balls are inhibited effectively by ZnO/TiO2/SiOx-chitosan composite coatings,And the preservation properties of composited coatings are better than single chitosan coating,and the preservation properties of ZnO/TiO2/SiOx-chitosan composite coating are the optimal,which is modified with sodium hexametaphosphate.3.The effects of ZnO nanometer microspheres modified with different Ag dosage on the properties of chitosan coatings were studied.The results show that after adding ZnO nanometer microspheres in the coatings which is modified by silver,the defect structure of the coating are reduced,mechanical properties and permeability of the coating are improved.Thereinto,the physicochemical properties of 0.5%Ag/ZnO-chitosan composite coating and 3.0%Ag/ZnO-chitosan composite coating are better than the others.The results of preservation properties of the chitosan composite coatings on the Hairtail fish balls at 4? show that the preservation performances of Ag/ZnO-chitosan composite coatings are obviously better than that of ZnO-chitosan composite coating and single chitosan coating.In addition,the 0.5%Ag/ZnO-chitosan composite coating is slightly better than the others.4.The antibacterial properties of the Ag/ZnO-chitosan composite coatings were researched using the dominant spoilage bacteria of aquatic products as the objects,which are Shewanella putrefaciens and Pseudomonas aeruginosa.Meanwhile,the effect of the coatings on the integrity of the cell membrane,permeability of the membrane,ATP and AKP enzymatic activities and protein expression are studied.The results show that the Ag/ZnO-chitosan composite coating can effectively inhibit the growth and reproduction of the target bacteria,change the synthesis and expression of the protein,as well as the increase of the permeability of cell membrane.