Preparation And Characterization Of Chitosan/flavones Composite Films

In this study,three flavones(apigenin,apigenin and luteolin)were added into the chitosan(CS)film,and D-α-tocopherol polyethylene glycol 1000 succinate(TPGS),which can improve the saturation solubility and stability of flavones,was also added to prepare food packaging film with good barrier,mechanical properties and biological activity.By comparing the structural characteristics,physical and chemical properties and biological activity of the prepared composite film,the composite film with the best performance were screened out.Subsequently,the selected flavones were made into nanoemulsion and added to the CS film to compare the effects of adding free and nano-encapsulated flavones on the performance of the CS film.(1)Chrysin,apigenin,luteolin were added into CS film,following by the addition of TPGS to improve the compatibility with the components.The prepared films were named CS-TPGS-CR,CS-TPGS-AN and CS-TPGS-LL,respectively.The microstructures,physical properties,antioxidant and antibacterial activities of CS-TPGS films containing different flavones were compared.Microstructure observation showed that incorporation of flavones somewhat reduced the homogeneity of the films.Flavones formed hydrogen bonds with other film components and changed the crystallinity of the films.As compared with CS-TPGS film,the films containing different flavones exhibited reduced tensile strength but enhanced UV-vis light barrier property and antibacterial activity.Among the films containing different flavones,the film containing luteolin showed the highest water vapor,oxygen and UV light barrier properties,tensile strength and antioxidant activity.However,the film containing chrysin exhibited the lowest water vapor,oxygen and UV light barrier properties and tensile strength but the highest antibacterial activity against Escherichia coli,Salmonella typhimurium,Staphylococcus aureus and Listeria monocytogenes.Our results suggested CS-TPGS film containing luteolin could be used as antioxidant and antibacterial packaging in food industry.(2)luteolin was further encapsulated in oil-in-water nanoemulsions that were emulsified by glycerol monooleate and Tween 20.Then,active packaging films were developed by incorporating free or nano-encapsulated luteolin into chitosan-based matrix.The microstructure,physical and functional properties of CS film containing free luteolin(CS-LL)or nano-encapsulated luteolin(CS-LLNEs)were compared.Results showed 68 mg luteolin-loaded nanoemulsions had the highest stability(Zeta potential of-39.8 mV)and encapsulation efficiency(89.52%).Different from CS film,CS-LL and CS-LLNEs films had compact inner microstructure and strengthened intermolecular interactions.Moreover,CS-LLNEs film was more homogenous and compact than CS-LL film.As a result,CS-LLNEs film presented higher water vapor and oxygen barrier abilities and mechanical properties in comparison with CS-LL film.In addition,CS-LLNEs film showed slower release rate of luteolin in 95%ethanol(fatty food stimulant)as compared with CS-LL film.Our results suggest CS-LLNEs film can be developed as an emerging active packaging material that has potential applications in food industry.