Effect Of Antibacterial Agent Size On The Performance Of Active Packaging Materials

With the rapid development of the economic and society,the lifestyle in a fast and convenient mode has become a worthy goal.The plastic products emerge at the historic moment.Plastic products have been widely used in the world and are increasing year by year,with the advantages of light in weight,waterproof,durable,mature of production technology and low in production cost.However,the plastic is not easy to degrade and some plastic components are potential hazards.Consequently,it is becoming an environmental source.Typically,the "white pollution" has become the focus of public concern.Food is the first thing for people,so we are meeting the higher challenges at the food packaging materials due to the consumers’ demand for food safety and quality.It drives the technical innovation of food packaging and development of environmentally-friendly packaging materials.Because of the biodegradability and non-toxicity of the natural polymer materials,the active food packaging made of natural polymer materials is becoming one of major research directions.In particular,the packaging with antibacterial function will have a significantly positive impact on food safety and shelf life extension.This study is aiming to assess the feasibility of constructing antibacterial packaging made of Zein and zinc oxide and to study the size effect of zinc oxide on the functions of active packaging.Here,Zein,as a natural edible polymer compound,has high yield,good film-forming property,caking,gel type,etc.It could form a film with the mesh structure by the molecule interaction with each other.Moreover,the forming Zein films have the strong oil absorption and keeping performances,excellent moisture resistance and oxygen barrier performance.In addition,zinc oxide,as a new kind of multifunctional inorganic materials,has a broad applications,especially as antibacterial agent.However,the activity of zinc oxide depends largely on its morphology and size.This paper firstly constructed the different routes to prepare zinc oxide crystals with different morphologies and sizes.Then the zinc oxide crystals were individually mixed with Zein to fabricate antibacterial packaging.The physical and chemical properties and antibacterial activity of Zein/ZnO films were compared.The results showed that the XRD test confirmed the inorganic composition of the synthetic materials.The ultraviolet and fluorescence tests verified that the as-prepared ZnO crystals have good optical properties.The bacteriostatic experiment results showed that the as-prepared ZnO crystals could effectively inhibit the growth of gram negative bacteria and gram positive bacteria.Additionally,the solvent evaporation had been documented to be an effective method to fabricate Zein/ZnO films.The SEM and EDX Mapping test results showed that the three kinds of Zein/ZnO film is uniform and transparent.The ratio of N and Zn got to 3:4,7:9 and 8:9,respectively.The ZnO content in Zein/ZnO films was 0.05 g/m~2,0.0176 g/m~2,0.02 g/m~2,respectively.The UV test results indicated that the store temperature at 37 ℃has a significant effect on the transparency of films,especially for that containing zinc oxide with the smallest size(long axis: 265.86 nm and short axis: 93.55 nm).The mechanical properties analysis indicated that Zein/ZnO films had good flexibility,tensile strength and breaking strength.The antibacterial tests proved that Zein/ZnO films had the excellent and long-term inhibition activities on gram negative bacteria and gram positive.Based on the abovementioned data,it could be concluded that Zein/ZnO films had the feasibility as food packaging and the size effect of zinc oxide was a key factor affecting the properties of Zein/ZnO films.