What Happens If You Don’t Refrigerate Eggs?

Eggs are a simple and healthy food rich in protein, calcium, and vitamin A. Unwashed and unaltered eggs don't need to be refrigerated.

Eggs are a simple and healthy food rich in protein, calcium, and vitamin A, but things get a bit more complicated when it comes to understanding the best methods of manufacturing and storing eggs.

If you’re from the United States, you’re used to refrigerating your eggs. You know where you’ll find them at the grocery store, tucked neatly in cartons and stored safely in refrigerated cases.

Should you travel abroad to some countries, including several in Europe, though, you might be startled to encounter an entirely different sight: eggs piled into stacks, commingling casually, and (gasp!) entirely unrefrigerated. Before you dismiss the eggs as unsanitary, take a deep breath. It’s not because these countries value fresh eggs any less — as it turns out, it’s just due to the different methods they use for treating eggs.

Along with Australians, Scandinavians, and the Japanese, Americans refrigerate eggs because of the way their manufacturers process them. In these countries, manufacturers wash eggs. They do this for two reasons:

• Hygiene. Due to the fact that bacteria and contaminants can exist on the eggshell, manufacturers believe it safer to remove the outer coating altogether.
• Presentation. Washing the egg makes it look prettier and cleaner, which may contribute to an image of freshness and better entice customers.

Once eggs are laid, they’re transferred into a machine for a bath in hot soapy water that kills any harmful bacteria living on the shell.

Unfortunately, this egg-washing method also comes with a downside. It turns out that eggs are coated with a protective barrier (called the "cuticle") that actually protects the integrity of the egg. Washing the egg removes the cuticle and results in a more permeable and porous egg. This allows water and oxygen to escape, makes the egg vulnerable to bacteria, and shortens its shelf life.

To counteract this problem, some U.S. manufacturers coat the egg in mineral oil after washing, which performs a similar function as the natural cuticle and increases the egg’s shelf life.

However, once the egg is washed and its cuticle is compromised, it must remain refrigerated in order to preserve freshness — whether or not it's coated in mineral oil.

In countries like Europe, manufacturers skip the egg washing altogether so that the cuticle remains intact and naturally protects the eggs. Because the eggs are unwashed and unaltered, there’s no need for consumers to refrigerate them at home.

There was a time when most countries washed and refrigerated their eggs, but there was no proven method for the process. When a batch of bad eggs made its way to England and made a bad impression on consumers, many countries blamed egg washing in general (rather than improper egg washing) and gave up on egg refrigeration altogether. Although the U.S. Department of Agriculture (USDA) perfected the process in the 1970s, most countries remained unconvinced and stuck with unwashed, unrefrigerated eggs.

As you’ve probably gathered, the method of cleaning and refrigerating eggs also takes a considerable amount of time, effort, and resources. Arranging for refrigeration (both during shipping from the farm to the store and in the store) can be expensive, and many countries cannot afford this additional cost.

The primary danger posed by raw eggs is Salmonella enteritidis (salmonella). Chicken ovaries can contain Salmonella bacteria that may infect the egg before it has the chance to create a protective cuticle.

While the cuticle does prohibit bacteria from penetrating the eggshell, that’s not the whole story. Biologically speaking, the cuticle is meant to protect the egg until it hatches — not until it’s eaten — and its primary function is promoting healthy incubation, not preventing Salmonella. Once the egg is laid, the cuticle degrades and eventually flakes off.

Symptoms of Salmonella food poisoning include:

• Stomach pain
• Diarrhea
• Vomiting
• Nausea

Symptoms begin 12 to 17 hours after consuming an infected egg and generally clear up on their own within 4 to 7 days. Regardless of washing or refrigeration, Salmonella can still exist in the egg yolk, but thoroughly cooking your eggs often removes even this risk of Salmonella. 

Today, only one out of every 20,000 eggs contains Salmonella, which is usually not life-threatening to begin with — however, it’s unpleasant. A fear of Salmonella is the main reason countries wash and refrigerate eggs.

Some European countries vaccinate hens against Salmonella before they start laying eggs, a move which has contributed to the lowest number of Salmonella cases the United Kingdom has seen since 1987. The U.S. doesn’t vaccinate hens but does require washing, many specific safety measures, and constant refrigeration.

Washed and refrigerated eggs may look more appealing, but the main benefit of refrigerating eggs is a dramatically extended shelf life.

One study of 5,400 eggs used the USDA grading standards (grades AA, A, and B, with grade AA being the best) to analyze the quality of eggs stored in the four most common ways: 

• Washed, refrigerated
• Washed, coated with mineral oil, and refrigerated
• Unwashed, stored at room temperature
• Unwashed, refrigerated

The results determined that the quality of room temperature eggs declined quickly, with unwashed room temperature eggs going from grade AA to grade B in only one week. Refrigerated eggs (whether oiled or unwashed) maintained their grade AA status for longer than 15 weeks.

It’s clear that washing and refrigerating eggs is a good strategy for longer-lasting eggs, but there’s usually no need to fear (quickly) eating unrefrigerated eggs when you are in a country with production protocols that produce unwashed, unrefrigerated eggs.

So, again: Do eggs need to be refrigerated? No — not unless you want them to stay fresher longer. Ultimately, the biggest difference between these two methods is the shelf life of the eggs.

One important thing to remember, though, is that once eggs are refrigerated, they must remain refrigerated. When left out, refrigerated eggs will start to sweat as their temperature increases. While one study found that allowing washed eggs to sweat won’t impact egg freshness, the USDA maintains that sweating can prompt bacteria growth and recommends that eggs shouldn’t be left unrefrigerated for more than 2 hours (1 hour if it’s hotter than 90 degrees Fahrenheit outside).

Whether you purchase unrefrigerated or refrigerated eggs, store them as you found them — and remember to eat those unrefrigerated eggs within a week or so.