Preparation And Application Of Polysaccharide Active Composite Film Containing Pickering Emulsion Of Clove Essential Oil Stabilized Cinnamon Essential Oil Pickering Emulsions

With the gradual increase in consumer safety awareness,edible packaging that is natural,safe,degradable and has antibacterial activity has become a hot research topic in the field of food packaging.Polysaccharides are widely used as film-forming substrates for edible packaging films because of their low cost,biodegradability and non-toxicity.However,single film-forming materials have certain defects in some properties,so compounding multiple film-forming substrates with antimicrobial active substances can improve the performance of films and impart antimicrobial activity to expand their applications in the packaging field.In this paper,pectin(PEC)and konjac gum(KGM)were used as film-forming substrates,and different concentrations of clove essential oil(CEO)Pickering emulsion were added to prepare active polysaccharide composite films.The problem of poor mechanical,barrier and antimicrobial properties of simple polysaccharide films was solved and the controlled release of essential oils in the film-forming matrix was achieved.Finally,the polysaccharide active composite coating films were applied to Juglans grapes for freshness experiments to explore their application prospects in fruit and vegetable preservation.The main research contents and results of this paper are as follows:(1)Rod-shaped particles CNC with nano-size,high crystallinity,high strength,and stability were obtained from cotton fiber by sulfuric acid hydrolysis and used as solid particle stabilizer for the preparation of Pickering emulsion(PE)of clove essential oil.Based on the single-factor test,the response surface experimental design method was used to examine the effects of different CNC concentrations,sonication power and sonication time on the emulsion properties,and the particle size was analyzed as an index to determine the optimal preparation conditions of Pickering emulsion.The average particle size of the resulting Pickering emulsion was 674.7±0.24 nm with a potential of-65.3±0.48 m V,which had good anti-centrifugal stability and storage stability,and good prevention of droplet coalescence and Ostwald ripening ability.(2)Pickering emulsions at different concentrations were added to PEC and KGM polysaccharide membranes to investigate the effects of Pickering emulsion addition on the functional activities of the composite membranes in terms of optical properties(color and light transmission),microstructure(SEM and FTIR),physicochemical properties(mechanical and barrier properties),antibacterial and slow-release properties.Compared with pure PEC/KGM films,the viscosity and modulus values of the composite film solution were reduced by the addition of Pickering emulsion,but the reduction was not significant for the appropriate Pickering emulsion addition(10% PE).At this time,the mechanical,barrier,and antibacterial properties of the film were significantly improved,and its tensile strength(TS)increased by 8.02 MPa,elongation at break(EAB)increased by 0.85%,water vapor transmission rate(WVP)decreased by 4.1×10-11 g/m.s.Pa,and the diameter of the antibacterial circle for Staphylococcus aureus(S.aureus)and Escherichia coli(E.coli),respectively The slow release experiments demonstrated that the release rate of CEO in food simulating solvent(95% ethanol)was slower in the film with 10% PE added and in the composite film with direct addition of essential oil,and the retention time of essential oil was increased by about 12 days under storage conditions of 25°C and 50%RH.(3)Based on the previous experiments,the polysaccharide-active composite coated films were used for the freshness experiments of Giant Peak grapes to explore the prospects of their application in fruit and vegetable preservation.Changes in appearance,weight loss,hardness,p H,soluble solids,Vc and polyphenol oxidase indicators were compared for uncoated(Control),PEC/KGM coated(PEC/KGM),PEC/KGM composite coated(PEC/KGM/CEO)with clove essential oil(1% vt)and PEC/KGM composite coated(PEC/KGM/PE)grapes with Pickering emulsion(10% vt)stored at 25°C and 55% RH for15 days.The results showed that the freshness preservation effect of PEC/KGM/PE >PEC/KGM/CEO > PEC/KGM > Control during 15 days of storage.polysaccharide-active composite film could effectively reduce the weight loss rate of grapes during storage,maintain fruit hardness,Vc,TSS,effectively inhibit the increase of p H and polyphenol oxidase activity,and extend the post-harvest shelf life of Chironomus grapes for 6 days after harvest.