| In this study,a bilayer film was prepared based on a polylactic acid film and a Pickering emulsion film,and a complementary bilayered polylactic acid film was combined with a Pickering emulsion film to prepare a bilayer film with excellent mechanical properties and barrier properties.It was found that Pickering emulsion can be loaded with cinnamon essential oil and slowly released into the food packaging environment,giving the film antioxidant and antibacterial properties.In the experiment,the bilayer film was prepared by a hot-pressing method that was conducive to industrial production.The effects of hot-pressing temperature and hot-pressing time on the mechanical properties and barrier properties of the bilayer film,as well as the effects of different hot-pressing temperatures on the antibacterial and anti-oxidation properties.?1?OSA starch was used as the raw material,and the best process conditions for the preparation of Pickering emulsion films were obtained through single factor test and response surface method optimization test.Response surface method optimization test obtained the best process conditions for the preparation of Pickering emulsion film:OSA starch particle concentration is 3.93 g/100 ml,glycerin addition amount is38.50%,Pickering emulsion addition amount is 11.11%,OSA/PIC is predicted The comprehensive membrane performance score is 0.769764.SEM images show that Pickering emulsion and OSA starch film matrix have good bio-compatibility,the emulsion droplets are evenly distributed in the film matrix,and the optimized Pickering emulsion film has good mechanical properties and barrier properties.?2?Preparation antibacterial and antioxidant Pickering emulsion films loading mixed oil?corn oil and CEO?.The research results show that the prepared Pickering emulsions have good emulsion stability and are applied to the film,and have good compatibility with the film.The Pickering emulsions embedded with mixed oil were incorporated into the OSA membrane liquid.The results showed that when the optimal ratio of mixed oil CEO4?equivalent concentration of cinnamon essential oil is 40%?,the tensile strength was 8.77 MPa and the elongation at break was 45.22%,the water vapor permeability is as low as 2.07×10-13g/?cm·s·Pa?,and the oxygen permeability is 1.54×10-5g/?m2·d·Pa?.FT-IR and SEM results showed that the OSA membrane matrix was compatible with Pickering emulsions containing mixed oil.The antibacterial circles were obvious in the antibacterial diagram.The test data showed that the antibacterial diameter of the film to B.subtilis can reach 24.60±1.38mm,the antibacterial diameter to S.aureus can reach 25.60±1.82mm,and the antibacterial diameter to E.coli can be up to 24.46±0.15mm.This indicates that the encapsulation strategy can effectively prevent the loss of essential oils of cinnamon essential oil during drying and storage.?3?The changes of the mechanical properties and barrier properties of the plasticized polylactic acid films with different proportions of the composite plasticizer at different storage times were studied.The binary composite plasticizer ATBC/PEG4000 can effectively improve the performance of polylactic acid film.For the composite plasticized film,when ATBC:PEG=1.5:0.5,the tensile strength of the polylactic acid film is 30.21MPa,and the elongation at break is 230%.The crystallization aging speed of the film plasticized by the composite plasticizer slowed down.With the extension of storage time,the performance of the polylactic acid film plasticized by the composite plasticizer decreased more slowly,and the crystallization aging speed slowed down.The SEM shows that the films structure is more compact when a certain proportion of composite plasticizer were added.However,with the addition of PEG in the composite plasticizer,there were many micropores in the cross section of the film,which may be due to crystallization Formation.?4?The hot-pressing method was used to prepare polylactic acid-pickling emulsion double-layer antibacterial and anti-oxidation film.When the hot pressing temperature was 110?and the hot pressing time was 120s,the mechanical properties and barrier properties of the bi-layer film are high.When the hot pressing temperature was110?,the tensile strength of the bi-layer film was 81.11MPa,and the elongation at break was 45%;when the hot pressing time is 120s,the tensile strength of the double-layer film was 76.5MPa,the elongation at break 55%.Tests have found that a certain hot pressing temperature will improve the antioxidant and bacteriostatic properties of the film,but excessively high temperature will destroy the film structure,thereby accelerating the release of active ingredients.When the hot pressing temperature was 110?,the diameter of the bacteriostatic circle of the bi-layer film is measured.The bacteriostatic diameter of the film against B.subtilis was 25.30±0.21mm,and the bacteriostatic diameter of S.aureus was 17.20±0.55mm,which inhibits E.coli.The diameter of the bacteria was 2.50±0.58mm.In short,the research shows that the bilayer films with antibacterial and antioxidative properties have good mechanical properties and barrier properties. |
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