Why Do We Refrigerate Eggs in the United States?

If you've ever wandered through a grocery store in another country, you've likely scratched your head over the cartons of eggs sitting unrefrigerated on pallets or shelves. Here in America, we'd never dream of letting eggs sit out for more than a few minutes, in the store or at home -- in fact, some of our refrigerators even come with molded plastic egg trays. So what's the deal? Should you continue to keep your eggs nice and chilled, or could you be saving valuable fridge space by keeping them in the pantry with the dry goods?

Tragically, the answer is no. Turns out American eggs, in spite of their constant refrigeration, are actually more vulnerable to salmonella contamination than the eggs you might see sitting out in, for example, Europe, where a tiny difference in agricultural regulations results in a big change in food storage standards.

Stateside Sanitation

The USDA Egg Grading Manual stipulates that all eggs intended for commercial sale should be washed in water that is at least ninety degrees, using detergent or sanitizer, and should be rinsed at an even higher temperature, also using sanitizer. The reason for this is to remove any fecal matter from the eggs that may contain salmonella or other harmful bacteria. Then the eggs are dried prior to packaging, because, as the manual notes, "Wetting a dirty shell provides moisture in which bacteria may breed and assists their growth and penetration through the shell."

So, per the USDA, salmonella from outside the shell has the potential to penetrate the shell if the egg isn't thoroughly washed and dried. But although that cleaning process can include up to 200 parts per million of chlorine bleach, it's still not enough to safeguard completely against salmonella contamination. That's where refrigeration comes in. Eggs that are unrefrigerated can develop moisture on their shells that encourages the growth of bacteria. Eggs that have been refrigerated in the store, but are then unrefrigerated for any period of time, can start to sweat, creating the same problem.

If only there were some kind of protective coating around the shell that would prohibit bacteria from penetrating into the edible part of the egg!

Oh. Wait. There is.




Story continues below

Natural Approach

Actually, as it turns out, eggs come already coated in a natural, protective cuticle. Hens produce this coating as they are laying, and it hardens within minutes. European Union egg marketing regulations put a lot of faith in the protection afforded by the cuticle, stipulating that eggs "should not be washed because of the potential damage to the physical barriers, such as the cuticle, which can occur during or after washing. Such damage may favour trans-shell contamination with bacteria and moisture loss and thereby increase the risk to consumers."

And that's not all. Because these eggs are reliant on the natural cuticle for protection from salmonella, they, too, are not supposed to experience temperature changes that could make them sweat -- but the EU arrives at the opposite conclusion of the USDA. "Cold eggs left out at room temperature may become covered in condensation, facilitating the growth of bacteria on the shell and probably their ingression into the egg," the EU's marketing standards state. "Therefore, eggs should be stored and transported preferably at a constant temperature, and should in general not be refrigerated before sale to the final consumer."

Comparative Effectiveness

So which approach does a better job of protecting consumers from salmonella? Should we all be storming Congress demanding an immediate change to the USDA manual, for the sake of our health? Well, not so fast. As the example of eggs indicates, here in America we tend to take a different approach to ensuring agricultural safety than our friends across the pond. We are less stringent about what happens on our farms -- which, as documented in a recent Rolling Stone expose, creates plenty of human health issues--and just worry about purifying the end product.

In the EU, on the other hand, regulations require that "appropriate and effective measures are taken to detect and control, amongst others, salmonella at all relevant stages and in particular at the level of primary production [emphasis mine], i.e. in flocks, in order to reduce the prevalence of food-borne zoonotic pathogens and thus the risk they pose to public health."

To check for contamination in the EU, agricultural workers are required to take "boot swabs," which are pretty much what they sound like, by walking around the "poultry house" until at least 50% of the area of the facility has been covered. In the US, by contrast, the USDA inspects eggs but not henhouses, which, per the New York Times, are "largely ignored by government inspectors."

The result is that salmonella contamination in chicken flocks is on the decline in the EU, while in the US contaminated eggs cause an estimated 142,000 cases of salmonella poisoning a year. So, unless our approach to production changes dramatically, it's probably not a good idea to risk leaving your eggs out on the counter.

We are dedicated to providing you with articles like this one. Show your support with a tax-deductible contribution to KCET. After all, public media is meant for the public. It belongs to all of us.

Keep Reading