Study On Nanosized ?-Fe₂O₃ Modified PVA-based Packing Material And Its Influence On Fresh Preservation Effect Of Clean Egg

In our market,most available eggs are dirty eggs.There are a lot of contaminants and bacteria adhesion in egg shell,especially some bacterial harm to human health and cause spoilage of eggs.Polyvinyl alcohol?PVA?is easily filming and biodegradable,sanitary and safe,so it shows broad prospect in food coating preservation.Beeswax which is hydrophobic oil substance has good barrier fresh performance in the packaging of food preservation,meanwhile beeswax antibacterial activity could avoid food spoilage which is due to microbial.Nano ?-Fe₂O₃ can improve water resistance of PVA,which also has visible light photocatalytic antibacterial properties,and further prevent microbial contamination.In this subject,composite emulsifier was used to emulsify beeswax and PVA,with nano ?-Fe₂O₃ modifying,optimized and analyzed the preparation conditions of process and performance,studied the nano-composite coating material influence long-term storage preservation effect of egg,the idiographic content and results are as follows:1.Research of nanosized ?-Fe₂O₃ and beeswax modified PVA based composite packaging material:The effluence of vapor permeability and moisture in beeswax and nanosized ?-Fe₂O₃ modified PVA packing material was determined by single factor experiment.With the response surface test method,it studied the modification for PVA with nanosized ?-Fe₂O₃,beeswax and optimized this coating material ratio of raw material;establishing a mathematical model,with vapor permeability rate of packaging film as objective function,the amount of ?-Fe₂O₃ and beeswax as experimental factors;Through researching,it finds that the increasing quantity of beeswax and the nano-?-Fe₂O₃ can lower the water vapor transmission ratio of PVA composite material effectively,therefore,there is a certain interaction between the two materials?P<0.05?.They have different optimal set of regression.The optimization of beeswax dosage is 0739g/100mL,while that of nano?-Fe₂O₃ is 0.04g/100mL,in which the water vapor transmission ratio gets to the lowest point,even lower than the former-PVA film 73.76%?P<0.05?.2.The research of basic properties of composite coating material beeswax:Study on antibacterial properties of composite packaging material in visible light with E.coli and Staphylococcus aureus.In visible light catalytic 180min,composite materials can reduce the total numbers of E.coli colonies an order of magnitude,Staphylococcus aureus colonies almost keep the same.Its abtimicrobial effect is through nanosized a-Fe₂O₃ producing a lot of hydroxyl radicals after light stimulates.These groups destroy cell wall so that the bacteria cells dissolve so as to achieve bacteriostatic effect.SEM measurement indicates that nanomaterial can evenly be distributed in PVA material relatively.XRD and FIRT measured showed that nano-a-Fe₂O₃ and beeswax can change the molecular chain arrangement of PVA,and increase intermolecular crosslinking,so that these two materials could reduce the swelling rate of composite packaging material?P<0.05?.3.The research of the effect of preserve clean eggs in coating composite packaging material:using unclean eggs,cleaning eggs and coating PVA material as control groups,coating composite material eggs as experimental group,stored at room temperature.Through the sensory index,physical and chemical properties,the shelf life of egg was analyzed and determined.The result shows that:composite material could prolong shelf life obviously.The experimental group had scattered yellow after 63 days,weightlessness rate was 8.55%,pH changed slight,the change range of hough unites and egg yolk index is much smaller than control groups,which were 32.51 and 0.092,the total number of colonies is the least.In conclusion,all the indicators of experimental group eggs are better than those of control groups.