Egg storage at a refrigerated temperature of 4°C significantly maintains shell egg quality, according to research performed by U.S. Department of Agriculture (USDA) Agricultural Marketing Service (ARM) Research Food Technologist Dr. Deana Jones at PEAK.
Additionally, washing and oiling eggs prevents weight loss at refrigerated temperatures and yolk quality is significantly diminished in the first 24 hours when eggs are stored at room temperature (22°C).
Storage and washing
Storage temperature and washing are two shell egg handling practices viewed differently depending on the country, Jones explained at the 2024 PEAK conference. Regulations in the U.S., such as the Food and Drug Administration’s (FDA) Egg Safety Final Rule, enforce refrigeration and washing, however, other countries do not have the same parameters.
While the two procedures are done in the U.S. to clean the egg surface, enhance quality and food safety and prevent spoilage, some countries refrain from performing them because it is perceived as not natural, can be costly and contradicts certain cultural preferences.
These differences cause issues when considering international shell egg trade, as trade has become more important to feed growing populations, meet customer demands and mitigate supply issues during disease outbreaks or recalls.
To understand how the difference in handling and storage temperature impacts shell egg quality, Jones and her team performed a side-by-side comparison of the practices.
The research
The study involved four treatments, all using commercial white eggs:
- washed and stored at 4°C storage
- washed oiled and stored at 4°C storage
- unwashed and stored at 4°C storage
- unwashed and stored at 22°C storage
Eggs were weighed almost every week for 15 weeks and quality assessments were performed throughout. It is important to note that the unrefrigerated eggs could only be measured through week six due to the significant decline in quality and weight.
The unwashed 22°C eggs were extremely lower in quality after six weeks of storage compared to the 4°C eggs after 15 weeks of storage, regardless of treatment. Eggs that were washed and oiled before 4°C storage consistently showed the lowest amount of weight loss.
Washed and unwashed refrigerated eggs exhibited comparable rates of egg weight loss throughout the 15 weeks of storage.
