Preparation And Antibacterial Activity Of Chitosan Modified Antibactrrial Packaging Film Based On Ionic Liquid

Food problems are closely related to our lives.In order to ensure the safety and hygiene requirements of foods in transportation and storage,we need to have corresponding food packaging materials.At present,most of the packaging is based on petroleum-based materials.In the face of increasingly serious environmental problems and resource shortages,a series of new packaging materials must be developed to replace synthetic plastics.Natural polysaccharides have attracted more and more researchers'attention as food packaging materials because of their low toxicity and biodegradability.Compared with other polysaccharides,chitosan has been widely selected as a film-forming substrate due to its excellent antibacterial and biocompatibility.In this paper,ternary composite membranes were prepared by chitosan and nano-titanium dioxide and anthocyanin.The main research contents are as follows:First,the chitosan was pretreated with tartaric acid,and the pretreated chitosan was washed with three detergents?ethanol,acetonitrile,acetone?,and then1-ethyl-3-methylimidazolium acetate?[EMIM]AC?solvents were used to dissolve the pretreated chitosan.The effects of pretreatment on dissolution time and film formation properties were investigated.The results showed that the pretreated chitosan had a dissolution time of 15 min in the ionic liquid,the dissolution temperature was reduced from 110°C to 65°C,the mechanical strength reached 24 MPa,the swelling degree was at least 78%,the water vapor transmission rate was at least 272.78 g·m^-2·d^-1,which overcomed the fragility of chitosan film at low concentration.Secondly,organic/inorganic hybrid membranes were prepared by adding titanium dioxide and anthocyanin to chitosan solution to improve the mechanical strength and bacteriostatic effect of the membranes.The results showed that the[EMIM]AC ionic liquid played a significant plasticizing role at a concentration of 2%.After adding 0.3%nano-titanium dioxide and 0.5%anthocyanin,the mechanical strength of the film was increased to 57 MPa.The water vapor permeability was reduced to 366 g·m^-2·d^-1,and the light transmittance was significantly reduced,which was only 0.85%at 350 nm.The film prepared by the solvent evaporation method was flat and dense,and the antibacterial property was remarkably improved to the large intestine.The antibacterial rate of bacillus and Staphylococcus aureus was above 90%,and the diameter of the inhibition zone was 10.4 mm and 11.2 mm,respectively.Thirdly,the preservation performance of chitosan composite membrane was studied to package cold fresh pork.The juice loss rate,pH value and volatile salt base of pork samples packed in the control group,blank group and experimental group were determined within 10 days.Nitrogen,bacterial colony number and sensory indicators were used to evaluate the preservation effect.The results showed that after storage for6 days,the pH of the sample was 5.79,the volatile base nitrogen content was 18.8mg/100 g,and the total number of colonies was 5.88 lg?CFU/g?.Compared with the control PE film,the cold film of the composite film packaging Pork storage can be extended for 3 days.