Study On Poly (Butylene Adipateco-Terephthalate)Nanocomposite Food Packaging Films And Its Application Of Cold Fresh Meat Preservation

Serious environmental problem caused by non-biodegradable plastics is a growing global concern.Poly(butylene adipate-co-terephthalate)(PBAT)is a biodegradable plastic material.An active food packaging films can be prepared from PBAT and antibacterial agents for application in food safety materials.In this paper,the nano-antibacterial agents were obtained through surface modified of TiO2 and Ag-TiO2 nano particles by three silane coupling agents.Then,the PBAT and PBAT nanocomposite antibacterial films were developed by incorporation of the nano-antibacterial agents into the PBAT matrix.Moreover,the storage and preservation effects of different nanocomposite antibacterial films on cold meat were investigated.The main findings were as follows:1.The surface of nano TiO2 and Ag-TiO2 was modified with three kinds of silane coupling agents(KH-560,KH-570 and KH-171).The results of infrared spectroscopy indicated that the silane coupling agents were successfully grafted onto nano Ti02 and Ag-TiO2 nanoparticles surface.Transmission electron microscopy(TEM)showed that the particle size remained the same before and after modification.Sedimentation experiment and grafting efficiency with mTiO2 showed that the content of KH-570 was 100%and the reaction time was 24 h,the sedimentation height was the smallest,and the grafting efficiency was largest(20.01%).When the surface of nano-AgTiO2 was modified,sedimentation experiment and grafting efficiency showed that the content of KH-171 was 40%and the reaction time was 24 h,the sedimentation height was the smallest,and the grafting efficiency was relatively high at 2.87%.2.PBAT nanocomposite films with different contents of mTiO2 and mAg-TiO2 were prepared by a solvent casting method.The morphology of PBAT nanocomposite films were studied by FE-SEM.The result showed that mTiO2 and mAg-TiO2 nanoparticles could be uniformly dispersed in PBAT,and the dispersibility of mTiO2 and mAg-TiO2 was significantly better than unmodified nanoparticles.With the increase of antibacterial agent content,the crystallinity of PBAT nanocomposite films increased first and then decreased.When the content of mTi02 was 1 wt%(P/mTl)and mAg-TiO2 was 2 wt%(P/mAT2),the crystallinity of the films were the largest.The addition of mTiO2 and mAg-TiO2 increased the tensile strength and elongation at break of the PBAT films,and enhanced the barrier properties of oxygen and water vapor.Compared with the pure PBAT film,the tensile strength and elongation at break of P/mTl and P/mAT2 films were the largest,and the OTR and WVTR were the smallest.In addition,the antimicrobial activity of PBAT/mTiO2 and PBAT/mAg-TiO2 nanocomposite films was extraordinary for against Gram-negative bacteria(Escherichia coli)and Gram-positive bacteria(Staphylococcus aureus).PBAT/mAg-TiO2 nanocomposite films had stronger antibacterial property than PBAT/mTiO2 films.In conclusion,the performance of the P/mTl and P/mAT2 composite films was relatively excellent.3.Fresh pork was packaged with PE fresh-keeping bags,pure PBAT film,P/mTl and P/mAT2 nanocomposite films and stored at(4±1)°C.During the storage time,the physiological and biochemical indexes of cold fresh meat were tested.At the same storage time,the aerobic plate count(APC)of cold fresh meat with P/mTl and P/mAT2 films was significantly less than PE and PBAT films,and the decrease rate of sensory quality,drip loss and Aw were relatively slower.After 9 days of storage,the pH of cold fresh meat with P/mAT2 and P/mTl was significantly lower than the control group.In addition,the TVB-N value of cold fresh meat with P/mAT2 and P/mTl was significantly lower than PE and PBAT groups.According to the physiological and biochemical indicators of cold meat,The shelf life of cold fresh meat in different groups was about as follows:PE control group(9d)<PBAT(12d)<P/mT1(21d)<P/mAT2(24d).Therefore,P/mAT2 has the best preservation effect on cold fresh meat,followed by P/mTl,both of which could effectively inhibit the growth of bacteria on the surface of cold fresh meat.Compared with the PE fresh-keeping bag,the shelf life of cold meat was extended by 12 to 15 days.