Effects of storage time and temperature on egg quality in old laying hens

The aim of the present study was to examine the effects of storage time and temperature and their interaction on the quality parameters of eggs obtained from aged laying hens. Eggs from 50-wk-old Bovans White hens were sampled immediately after being laid and subjected to storage periods of 2, 5, and 10 d at 5, 21, and 29 degrees C. Extension of the storage time up to 10 d and temperature up to 29 degrees C resulted in significant deterioration of egg quality. Albumen height, Haugh unit, pH of albumen and yolk, specific gravity, and air cell size have been found to be the most important parameters and were greatly influenced by storage time and temperature. In a 10-d storage period Haugh units were 76.3, 53.7, and 40.6 when stored at 5, 21, or 29 degrees C, respectively. The size of air cell (distance between eggshell and membrane) exceeded 4 mm when eggs were stored 2 d at greater than 21 degrees C. Rapidly increased pH in albumen with 2 d storage time was observed, regardless of storage temperature. Likewise, pH during a 5-d storage period continued to increase from 7.47 to 9.2 at 29 degrees C. Interaction effects between storage time and temperature were also significant for egg weight loss, specific gravity, air cell size, Haugh unit, albumen height, and pH. The results of the present study suggested that Haugh unit, pH of albumen, and air cell size were the most important parameters influenced by the storage period and storage temperature in laying hens.