To investigate the effects of irradiation on structural and functional properties of egg white proteins, which enhance foaming ability, egg white was separated and irradiated at doses of 0, 2.5, and 5 kGy. The foaming ability of egg white was increased, whereas foam stability was decreased by irradiation. Turbidity and protein oxidation of egg white was increased by irradiation with an increase of irradiation dose. The content of free sulfhydryl and disulfide was not affected by irradiation. According to 2-dimensional electrophoresis analysis, it was demonstrated that protein scissions are the main changes caused by irradiation and this protein modification may be the main reason for the improvement in foaming ability of egg white.

To develop a method that can maintain egg freshness during practical storage conditions, eggs were coated with chitosan and stored with or without dry ice. The physicochemical and microbiological qualities of eggs were evaluated during 14 d of storage at 4 and 23°C without dry ice and at 23°C with dry ice. The combination of chitosan coating and dry ice significantly inhibited a Haugh unit decrease during storage at 23 °C. No difference in functional properties, such as foaming ability, foam stability, and viscosity, among treatments was observed, but chitosan coating and storage with dry ice decreased the rate of pH increase and moisture loss in albumen at d 7 and 14. The eggs treated with chitosan coating and storage with dry ice had a significantly lower number of Salmonella Typhimurium inoculated on the egg surface than did control eggs during storage at 23°C. Results revealed that the combination of chitosan coating and storage with dry ice limited the moisture loss, CO(2) emission, and pH increase, which helped maintaining the freshness of eggs. Microbial growth was also inhibited during storage at 23°C.