Gas Permeability And Permselectivity Of Poly(L-lactic Acid)/SiOx Film And Its Application In Modified Atmosphere Packaging For Chilled Meat

To extend the shelf-life of chilled meat,a layer of SiOx was deposited on the surface of poly(L-Iactic acid)(PLLA)film by plasma enhanced chemical vapor deposition(PECVD)process,to fabricate PLLA/SiOx layered films,which showed higher gas barrier and gas permselectivity,compared with the neat PLLA film.Meanwhile,sterile filter papers were soaked in the tea polyphenol(TP)suspension liquid to prepare the fresh-keeping pad.Then,the PLLA/SiOx films and TP pads were combined and applied to the equilibrium modified atmosphere packaging(EMAP)of chilled meat.The deposition effect of the PLLA/SiOx film was analyzed by the attenuated total reflectance fourier transform infrared spectroscopy(ATR-FTIR).The optical transmittance of the PLLA/SiOx film was measured using a UV-vis spectrophotometer,and the surface topography was analyzed by the scanning electron microscopy(SEM).The tensile test was performed to evaluate the mechanical properties.The oxygen,carbon dioxide,and water vapor permeability were investigated to evaluate the barrier properties of PLLA/SiOx films.The potential benefits of the packaging treatments on headspace gas composition,total viable count(TVC),total volatile basic nitrogen(TVBN),thiobarbituric acid reactive substances(TBARS),and sensorial changes of chilled meats were also evaluated.In summary,the main packaging performance of the PLLA/SiOx films were evaluated by appropriate characterization methods,and the results are as follows:(1)A series of PLLA/SiOx films were prepared by PECVD.and the film with a deposition time of 60 minutes(PLLA/SiOx60)has the optimum comprehensive package performance.PLLA/SiOx60 film showed Young’s modulus and tensile strength increased by 119.2%and 91.6%respectively,over those of neat PLLA film.At 5℃.the oxygen(O2)and carbon dioxide(CO2)permeability of PLLA/SiOx60 film decreased by 78.7%and 71.7%respectively,and the CO2/O2 permselectivity increased by 32.5%,compared to that of the neat PLLA film.(2)When the PLLA/SiOx60 film was applied to the EMAP of chilled meat,the gas composition in packaging reached a dynamic equilibrium with 6～11%CO,and 8～13%O2,which was kept longer than that in neat PLLA packaging.Combined with the TP pads which effectively inhibited the microbial growth,the desirable color of meat was maintained and an extended shelf-life of 52 days was achieved for the chilled meat.The above results proved that there is a synergistic preservation effect between the PLLA/SiOx films and the TP pads,therefore an environmental protection packaging system can be established.