Effects of Edible Zein and Chitosan Coating Assimilated by Oregano Essential Oil on the Quality Parameters of Egg

Undesirable changes including the exchange of carbon dioxide and humidity through the shell-pores and cracks, take place immediately following the lying of egg. One of the main strategies to control these defects is coating the egg-shell by oil and polymer materials. In the present study, the effect of chitosan (2%) and zein (10%) biopolymers alone and in combination with oregano-essential oil (EO) on internal changes such as percentage of weight loss, pH, Haugh unit, Yolk index and egg quality, as well as sensory factors including surface smoothness, odor, surface glossiness and overall acceptability of the eggs stored for 5 weeks at 25C, were investigated. The results showed significant differences between all treatments and controls (P < 0.05). Incorporation of EO to the chitosan and zein coating solutions had not significant effects on internal factors of all treatments during the storage period (P > 0.05). In the sensory evaluation of eggs coated with chitosan and EO, the results showed significant differences with chitosan solution alone whereas, such differences could not be observed for zein and zein plus EO samples. Therefore, coating with both the biopolymers had considerable impact on the internal quality of eggs. In addition, the coating extended the shelf-life of eggs to 2-4 times at the room temperature. Moreover, when EO added to the coating solution, enhanced consumer acceptability of all the coated eggs was observed.