Study On Preparation And Properties Of PVA Antibacterial Preservative Film Of Cinnamon Essential Oil Nanocapsules

As the single structure and function of conventional plastic wrap,they can not meet the modern high-quality fresh fruit and vegetable requirements,new multi-functional plastic wrap is urgently be developed.The rise of nanomaterials offers more possibilities for the development of multifunctional and diversified plastic wrap.The subject adopts the nanocapsule technology,and the natural antibacterial agent（cinnamon essential oil）is adsorbed in the calcium carbonate nanoparticles to prepare a sustained-release essential oil nanocapsule with good biological activity,and then added to the PVA film to prepare an antibacterial activity.On this basis,the preservation effect of the cling film on the cherry tomatoes was verified.The main findings are as follows:（1）CaCO₃-PDA hollow nanoparticles were synthesized by adding calcium ions to polydopamine.At the same time,the effects of different absolute ethanol volumes（100 m L,200 m L,300 m L,500 mL）on the formation of hollow structure of calcium carbonate nanoparticles were investigated.The hollow structure of CaCO₃-PDA under each reaction system was observed by transmission electron microscopy（TEM）.It was found that the hollow structure of CaCO₃-PDA in 300 m L system is the best,which can be used as the wall material for preparing nanocapsules.（2）Cinnamon essential oil was selected as the antibacterial material,and powdered cinnamon essential oil nano-microcapsules were prepared by using the preferred CaCO₃-PDA（under 300 mL system）as the wall material.The loading amount of the microcapsules was tested,and the particle size analysis was carried out to obtain that the loading amount of the microcapsules was up to 51.2 mg/g,and the average particle diameter of the microcapsules was about 111 nm,indicating that the microcapsules reached the nanometer level.（3）Using PVA as substrate and cinnamon essential oil nano-microcapsule as antibacterial agent,combined with other additives to prepare PVA antibacterial plastic wrap containing essential oil nanocapsules.SEM,TEM,GC-MS and other means were used to characterize the performance of antibacterial plastic wrap with diffierent amount of microcapsules（0.5,1 and 2wt%）The thickness of the antibacterial wrap film was measured by mechanical method to be between 0.025±0.009 mm.Through the tensile strength test of the film,it was found that the tensile strength and tensile strain at break increased first and then decreased with the increase of the content of essential oil capsules.When the amount of essential oil capsules increased to 1 wt%,the tensile strength and fracture The tensile strain is basically no longer changed,and the mechanical properties are relatively stable.It was observed by scanning electron microscopy that the surface of the PVA antibacterial wrap film was somewhat uneven and not smooth,but the distribution of the nano microcapsule particles was relatively uniform.Through the GC-MS measurement,the content of free cinnamon essential oil in PVA antibacterial plastic wrap increased with the increase of the amount of essential oil microcapsules.In the 0.5 wt%PVA antibacterial cling film,the loading of cinnamon essential oil is 1.56±0.09μg/mg.When the amount of essential oil microcapsules is increased to 1 wt%,the essential oil loading of the antibacterial film is almost twice that of 0.5 wt%cling film.However,as the amount of microcapsules added continues to increase,the loading efficiency of the film will no longer increase.（4）The cherry tomatoes was selected as the research object.After packaging with the prepared PVA antibacterial plastic wrap,the preservation effect of the cling film on the fruit was verified by measuring the content of some physiological indexes of the fruit.The antibacterial plastic wrap with different microcapsule addition amount（0.5,1 and2 wt%）has certain antibacterial effect,which can reduce the water dispersion of the cherry tomatoes during storage to some extent,after 15 days of storage,the weight loss rate of the1 wt%antibacterial plastic wrap packaging group was only 18.44%;delay the softening of the cherry tomatoes and reduce the reduction of TA、Vc and SSC content.Maintains good morphology and high quality of the cherry tomatoes.At the same time,it can alleviate the decrease of POD,SOD and CAT content of the fruit of the fruit,enhance the antioxidant capacity of the fruit,and delay the aging of the fruit.In particular,when the amount of microcapsules added is 1 wt%,the antibacterial wrap film has the best preservation effect.（4）Selecting the cherry tomatoes as the research object,after packaging with the prepared PVA antibacterial plastic wrap,the preservation effect of the plastic wrap on the cherry tomatoes was verified by measuring some physiological indicators.The results show that the nano-capsule technology is used to adsorb the cinnamon oil and then added to the PVA film.The PVA anti-bacterial wrap film has good performance and has good antibacterial effect when used for fresh-keeping packaging of the cherry tomatoes.