Abstract: In this paper, the changes in moisture content, oxidation condition, texture and color of boiled eggs with and without shell were studied during storage at refrigerator (4 ℃) and room temperature (25 ℃), respectively. The moisture distribution, microstructure change and textural properties were determined using low field nuclear magnetic resonance, scanning electron microscopy and texture analyzer. The effects of protein and fat oxidation on the quality change were studied through carbonyl content and thiobarbituric acid reactive substances content. The results indicated that the moisture content in white and yolk of boiled eggs, especially immobile water content, was decreased during storage (P < 0.05), but the degree of protein and fat oxidation was increased, and shelling treatment was an important factor affecting these changes. At the same time, the hardness and chewiness of boiled egg increased gradually as the storage time was prolonged. The microstructure of egg white gel was denser and the sensory quality was lower than that of freshly boiled egg white gel, but the quality of boiled egg white with shell at refrigerator temperature (4 ℃) changed minimally among all experimental groups. Storage temperature had no significant effect on the color of boiled eggs (P > 0.05), but shelling treatment could change the color of boiled eggs significantly (P < 0.05). On the basis of the above results, the moisture loss and oxidization of boiled eggs were the major reasons for egg quality deterioration. In conclusion, storage at 4 ℃ is recommended for boiled eggs with shell.

Key words: boiled egg, storage, moisture distribution, quality