Preparation Of Mussel-inspired MMT-AgNPs/polylactic Acid Composite Antibacterial Film And Its Application In Food Preservation

Inspired by the adhesion of mussels in nature,a new type of PLA-based antimicrobial food packaging film was prepared by solvent evaporation method using polydopamine(PDA)as a secondary reaction platform and nano-silver(AgNPs)loaded Montmorillonite(MMT-AgNPs)composite antimicrobial particles as the main raw material and polylactic acid(PLA)as the filler.The properties of MMT-AgNPs and PLA-based antimicrobial films and their effects in practical storage were systematically studied..Firstly,a simple green method was used to synthesize silver nanoparticles in situ using polydopamine as surface modifier,reductant and stabilizer.MMT-AgNPs composite antibacterial particles were successfully prepared.Infrared spectrum(FTIR),X-ray diffraction(XRD),transmission electron microscopy(TEM)and thermogravimetric analysis(TGA)showed that the modified MMT was successfully modified by PDA.The modified MMT retained its original phase structure.AgNPs were successfully loaded on the surface of MMT with a mass fraction of 3.4%.The results of antibacterial experiment showed that MMT-AgNPs showed strong antibacterial activity against E.coli and S.aureus,and the antibacterial rate reached more than 99.9%.Nextly,PLA/PDA/MMT-AgNPs composite antibacterial film was prepared by solution blending with dichloromethane as solvent.SEM test showed that MMT-AgNPs were uniformly dispersed in PLA matrix,and they had good compatibility.Tensile,vapor permeability and TGA measurements showed that the thermal stability of the composite films remained unchanged,and the tensile strength,hydrophilicity and contact angle increased.Antimicrobial test showed that only a small amount of MMT-AgNPs composite antibacterial film showed excellent antibacterial activity against E.coli and S.aureus,and the antibacterial rate reached more than 95%.When the mass fraction of MMT-AgNPs was 2.0%,the antibacterial rate of composite film against E.coli and S.aureus reached 99.9%.Lastly,The raw meat mince was packaged with commercial PE,pure polylactic acid film and antimicrobial composite film respectively and stored at 4?.The changes of physiological and biochemical indexes of raw meat mince during storage were regularly tested.The results showed that 2%antimicrobial composite film had the best fresh-keeping effect on raw meat mince,and significantly controlled the quality loss and pH change of raw meat mince,effectively inhibited the micro-corruption in raw meat mince.The shelf life of raw meat mince was prolonged by 3-4 days.