Is Refrigeration Necessary for Egg Safety?

It’s common knowledge that eggs can be found right next to cheese, yogurt and other refrigerated dairy products at the supermarket. Well, that’s the case in the United States, anyway. Surprising as it might sound, eggs sold in many European countries are placed on unrefrigerated shelves, and are often located towards the center of the store next to baking supplies. While this might appear to be an unsanitary practice, there is some evidence that indicates that the Europeans have the right idea.

Differing Preparation Methods

To understand why eggs sold in the United States are refrigerated, it’s necessary to review how they are prepared for human consumption. Regulations issued by the US Department of Agriculture (USDA) mandate that eggs must be first be washed in hot water before they can be sold commercially; this water has to be at least 90°F (or 32.2 degrees Celsius).

During this step, egg producers must also apply a detergent to their product; this detergent must not leave behind any unnatural odors on the eggs. The eggs must then be rinsed with even hotter water, which should likewise be mixed with a chemical sanitizer. After being rinsed, the eggs are dried to prevent excess moisture from clinging to their shells. Not surprisingly, the reason for this entire process is to remove bacteria from the eggs.

Across the pond, however, the egg preparation process differs greatly. In fact, the European Union (EU) actually prohibits farmers from washing or cleaning their eggs. The EU’s reasoning for this decision is that such precautions are unnecessary, since eggs have a natural layer of protection that blocks contaminants from getting inside the egg. This layer, known as the cuticle, is applied to eggs immediately before they leave the hen’s body. EU regulators contend that washing and cleaning eggs could erode the cuticle, rendering eggs more vulnerable to contamination.

The Role of Refrigeration

This brings us as to why the eggs you buy at the store are placed in such cold temperatures (assuming your American). Though American eggs must undergo a thorough washing and drying process, they can still be contaminated with harmful bacteria, especially when left in unrefrigerated environments. This can allow moisture to develop on the outside of the eggs, providing a fertile breeding ground for bacteria. In turn, these bacteria can easily get inside the egg through the numerous pores on the shell. Refrigeration keeps eggs dry, thereby preventing bacteria from forming.

While the cleaning process removes harmful contaminants from eggs, it also removes most of the egg’s cuticle. Because of this, eggs produced in the United States must constantly remain at cool temperatures; the USDA mandates that eggs be exposed to temperatures no higher than 45°F.

The EU also has egg regulations pertaining to temperature. Unlike the USDA, however, EU laws dictate that eggs “should in general not be refrigerated before sale to the final consumer.” Instead, the standards created by the EU call for eggs to be kept in environments with “cool” room temperatures. If stored in refrigerated environments, the EU is concerned that condensation will develop on the surface of eggs, fostering the growth of harmful bacteria.

Which Way is Better?

Before comparing US and EU rules regarding egg storage and preparation, it should be noted that European farmers must follow additional regulations related to agricultural safety. For example, farmers in EU countries must regularly check for contaminants by taking boot swabs, a process in which special boots collect samples from the floors of poultry houses. Likewise, nearly all eggs sold in Britain come from hens that have received salmonella vaccinations. Only one-third of American farmers give their flocks this vaccination, as many view the vaccine as too expensive to use.

These additional regulations might explain why reported salmonella cases have steadily decreased in EU countries over the last several years. In 2005, there were over 40 cases of human salmonella poisoning per every 100,000 people in the EU; by 2009, this figure had been reduced to roughly 25 per every 100,000 individuals. Furthermore, the number of reported salmonella cases in Britain declined sharply after the hen vaccination program was introduced, dropping from 14,771 in 1997 to only 581 cases by 2009.

An argument can certainly be made that European standards for egg farming and production are more effective those mandated by the USDA. Since major changes in US regulations don’t appear to be on the horizon, however, American shoppers should still refrigerate eggs in order to prevent contamination.