Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 12, 2005
Publication Date: November 1, 2005
Citation: Jones, D.R., Musgrove, M.T. 2005. Effects of extended storage on egg quality factors. Poultry Science.84(11):1774-1777 Interpretive Summary: The length of 'sell-by' dates printed on egg cartons are set by state regulatory officials in the US. Most states base their decisions on quality deterioration during storage. Since product is marketed as graded (i.e. Grade A or Grade B), it must still meet the minimum requirements of this grade classification at the time of retail. Much of the egg quality research used as a basis for today's quality standards was conducted 30-50 years ago. Since that time, hen genetics, flock management practices, hen nutrition, processing parameters, and other factors have changed dramatically. The current study was undertaken to determine how the physical quality of the egg changes during extended cold storage. Egg weight decreased during storage. Albumen height and Haugh unit values (both measures of interior egg quality) decreased. Shell strength did not change during storage. Vitelline membrane (membrane around the yolk) elasticity decreased during extended cold storage. This could lead to a greater decrease of yolk rupture during cracking by the consumer. Even after 10 weeks of storage, interior quality factors still remained in the Grade A range. The results of this study indicate that current 'sell by' guidelines could be extended if based on egg quality factors which would allow the industry a longer period to market their product.
Technical Abstract: Eggs were collected from a single in-line processing facility once a week for three weeks (replicates). All eggs were stored at 4C and 80% RH for the 10 wk study. Analyses began the day after collection and continued each week of storage. Two dozen eggs were examined for egg weight, albumen height, Haugh unit, shell strength, and vitelline membrane strength. Eggs from the second replicate were significantly (P < 0.0001) heavier than the other replicates by an average of 3 g. Egg weight decreased (P < 0.0001) from approximately 61 g to 57 g after 10 wk of storage. Albumen height was approximately 0.2 mm higher for the eggs in replicate two compared to the other replicates (P < 0.01). On average, albumen height decreased with extended storage (P < 0.0001) from 7.05 mm to 4.85 mm. Haugh unit values decreased during cold storage from 82.59 to 67.43 (P < 0.0001). There were no differences between replicates for Haugh unit values. No differences were detected for shell strength between replicates or during extended storage. A significant difference (P < 0.05) was found in detectable force required to break the vitelline membrane between replicates. This difference was less than 0.05 g. The elasticity of the vitelline membrane decreased during storage (P < 0.01) remaining low after 6 wk. Extended cold storage led to decreases in egg weight, albumen height and Haugh units. Average Haugh unit values were still within the range for Grade A. Shell strength was not affected by extended storage. Vitelline membrane elasticity also decreased which could lead to yolks more easily rupturing as consumers crack the eggs.