Preparation Of Nano TiO₂-PVA Film And Its Preservation Of Fresh Cut Apples

Fresh-cut fruits and vegetables are becoming popular all over the world because of their convenience,freshness and health benifits.The shelflife of fresh-cut fruits are limited caused by their postharvest breathing and mechanical injury.Active packaging is a potetial solution to extend the shelf-life of the fresh cut fruits and vegetables.In this study,modified PVA-TiO₂ films with bacteriostatic were prepared to preserve the fresh cut apples.The water resistance and mechanical propertities of modified PVA-TiO₂ film was improved by adding crosslinkers such as acetic acid,carbamide and MgCl₂.Nano TiO₂/PVA-PLA bilayer film was devolped and optimized by the response surface methodology.Physicochemical and mechanical properties,thermodynamic properties,microstructure,bacteriostasis of the modified PVA-TiO₂ film were studied,and their preservation of the fresh-cut apple were investigaed as well.It was found that the water resistance of PVA-TiO₂ film was significantly improved by different modifiers.The water resistance of PVA-TiO₂-MgCl₂ film was the best.Compared with PVA film,its solubility decreased by 73.32%,and the contact angle increased by51.49%.Its inhibition rate of E.coli and Staphylococcus aureus at 24 h was 39.90%and 34.98%,respectively.The optimum formulation of the nano TiO₂/PVA-PLA film was PVA 1.18 g,soluble starch content 1.05 g and PLA content 1.03 g.The solubility of the film was 21.38%,the contact angle was 91.83°.The film had good mechanical properties and stable thermodynamic properties,and it showed good inhibition capacity to Escherichia coli and Staphylococcus aureus.PVA-TiO₂-MgCl₂ and TiO₂/PVA-PLA film were then applied for preservation of fresh-cut apples?FCA?at 4?,and the commercial PE film was used as the blank and PVA film as the control.The quality attributes,physiological properties and microbial spoilage of FCA were studied.It can be found that the modified PVA-TiO₂ films could regulate the gas environment in the packaging,inhibit the growth of microorganisms,and thus extend the shelf life of FCA to 12 days.The browning index of the blank sample was 1.31 times higher than that of sample in each modified PVA-TiO₂ film.The pH of FCA in the PE film was significantly higher?P<0.05?than that in the modified PVA-TiO₂ films.The hardness of the FCA in the PE film decreased 55.46%more than that in the PVA-TiO₂-MgCl₂ film.In addition,both the two modified PVA-TiO₂ films could maintain the content of TSS and TA and inhibit the activity of POD and PPO.