Fresh-keeping effect of different coating materials on clean egg

Abstract: Nano-α-Fe2O3 and beeswax modified polyvinyl alcohol based composite material which had been researched by our lab team before had good antibacterial properties and water-resisting performance. On the basis, this paper will study whether the nano-α-Fe2O3 and beeswax modified polyvinyl alcohol based composite material could extend shelf life of clean eggs or not.Uncoated clean eggs were chosen as control group. Secondary soaking coating method were adopted to coat eggs and the coating process was putting clean eggs into coating liquid for one minute, and being taken out and then being blowing dried, and did the above-mentioned process again. All eggs were preserved in same preserved condition whose temperature and the relative humidity changed as time went on for 42 days. During storage the physical and chemical indicators include the yolk index, Haugh unit, albumen pH, and the egg weight loss were detected every week to determine the egg freshness. The other materials, polyvinylidene chloride and nano-Fe3+/TiO2 and lac modified polyvinyl alcohol based material, were used as two control groups compared with nano α-Fe2O3 and beeswax modified polyvinyl alcohol based composite material. Their characteristics ,e.g. antibacterial properties and water-resisting performance had been studied before.After storage for 42 days eggs were coated by nano-Fe3+/TiO2 and lac modified polyvinyl alcohol based material (C group) whose egg grade was B, yolk index was 0.29, Haugh unit was 56.95, and albumen pH value was 9.32, and fresh eggs rate was 100% and the weight loss rate was 3.33%. The clean eggs coated by nano α-Fe2O3 and beeswax modified polyvinyl alcohol based composite material (B group) had 100% of fresh eggs rate, 3.05% of the weight loss rate , had A egg grade , 0.32 of Yolk index, 60.788 of Haugh unit, and 9.2 of albumen pH value , 1.9×103CFU/mLof total plate count , and were superior to control group and other treatment groups. However, the yolk of A group ( eggs coated by Poly vinylidene chloride) spreaded out at 35 days and control group (CK group) was at 28 days. The initial values of A group such as the egg weight loss rate and yolk index and albumen pH were better than other groups, and after 21 days storage they were worse than the other coating groups.The results showed that the quality of coating eggs were better than the eggs of control group under the same storage conditions, and the eggs coated by nano-a-Fe2O3 and beeswax modified polyvinyl alcohol based composite material had the best quality. The change of temperature and humidity would influence material barrier performance e.g. the preservation effect of polyvinylidene chloride reduced as humidity changed. In addition, the cost of nano-α-Fe2O3 and beeswax modified polyvinyl alcohol based composite material was lower and its operation process was simple, so that it would have the prospect of industrial application.