Many Americans are shocked to enter a European supermarket and find that eggs are stored outside of the fridge.
This is because authorities in most European countries say refrigerating eggs isn't necessary. But in the US, it is considered unsafe to store eggs at room temperature.
This leads some people to believe that Americans are overly cautious when it comes to egg storage, while others believe Europeans are too relaxed.
So who is right? As it turns out, both are.
It's All About Salmonella
Salmonella is a type of bacteria that lives in the intestines of many warm-blooded animals. It's perfectly safe when contained within the animal's intestinal tract, but it can cause serious illness if it enters the food supply.
An infection from Salmonella can cause unpleasant symptoms like vomiting and diarrhea and be especially dangerous — even fatal — for the very old, the very young or those with compromised immune systems ().
Common sources of Salmonella outbreaks are alfalfa sprouts, peanut butter, chicken and eggs. In the 1970s and 1980s, eggs were found to be responsible for 77% of Salmonella outbreaks in the US (, ).
This prompted efforts to improve the safety of eggs, and the rates of infections have since decreased, although Salmonella outbreaks from eggs still occur ().
An egg can be contaminated with Salmonella either externally, if bacteria penetrate the eggshell, or internally, if the hen itself carried Salmonella and the bacteria was transferred into the egg before the shell formed ().
How eggs are handled, stored and cooked is essential for preventing Salmonella outbreaks from contaminated eggs.
For example, storing eggs below 40°F (4°C) halts the growth of Salmonella, and cooking eggs to at least 160°F (71°C) kills any bacteria that is present.
While eggs aren't any different in the US and Europe, the way they're treated for Salmonella is. Therefore, whether your eggs need to be kept in the fridge or not really depends on how your country tackles Salmonella.
Bottom Line: Salmonella is a type of bacteria that is a common cause of foodborne illness. How countries treat eggs for Salmonella determines if they need to be refrigerated or not.
Eggs Should Be Refrigerated in the US
In the US, Salmonella is mostly treated externally. Before eggs are sold, they go through a sterilization process.
They are washed in hot, soapy water and sprayed with a disinfectant, killing any bacteria that might be on the shell (, ).
A handful of other countries, including Australia, Japan and Scandinavian countries, treat eggs the same way.
This method is highly effective at killing the bacteria found on egg shells. Unfortunately, it does nothing to kill bacteria that may already be present inside of the egg, which is often what makes people sick (, , ).
The washing process may also remove the cuticle of the egg, which is a thin layer on the eggshell that helps protect it.
If the cuticle is removed, any bacteria that come into contact with the egg after sterilization will more easily be able to penetrate the shell and contaminate the contents of the egg (, ).
While refrigeration does not kill bacteria, it reduces the likelihood of you becoming sick by keeping the number of bacteria limited. Refrigeration also makes it more difficult for bacteria to penetrate the eggshell (, ).
However, there is another important reason that eggs must be kept in the refrigerator in the US. To keep bacteria to a minimum, the FDA requires commercially sold eggs to be stored and transported below 45°F (7°C).
And once eggs have been refrigerated, they must always be kept refrigerated to prevent them from forming condensation if they warm up. The moisture makes it easier for bacteria to penetrate the eggshell.
So whether you are willing to take the risk of coming across a contaminated egg or not, the fact that eggs in the US are washed and refrigerated before purchase means they really should be kept that way.
Bottom Line: In the US and a few other countries, eggs are washed, sanitized and refrigerated quickly after being laid in order to minimize bacteria. Therefore, eggs must remain refrigerated.
Eggs Don't Have to Be Refrigerated in Europe
Many European countries do not refrigerate their eggs, even though they experienced the same epidemic of Salmonella cases in the 1980s.
While the US chose to control Salmonella contamination through egg washing and refrigeration, many countries in Europe have chosen to improve sanitation and vaccinate hens against Salmonella, preventing infection in the first place (, ).
The UK is a shining example of this. After a mandatory campaign to vaccinate all egg-laying hens against the most common strain of Salmonella, the number of Salmonella cases in the country dropped to the lowest level in decades ().
Contrary to the US, washing and disinfecting eggs is illegal in the EU (Sweden and the Netherlands are exceptions) ().
While this may seem unsanitary to Americans, the logic is that the egg cuticle and shell are left undamaged, functioning as a layer of defense against bacteria ().
In addition to the cuticle, egg whites also have natural defenses against bacteria, which can help protect the egg for up to three weeks (, ).
Therefore, it is considered unnecessary to refrigerate eggs.
In fact, the EU recommends that eggs be kept cool, but not refrigerated, in supermarkets in order to prevent eggs from warming up and forming that unwanted condensation during the trip home.
Because eggs in the EU are treated differently than in the US, it's fine to keep eggs out of the refrigerator as long as you plan to use them soon.
Bottom Line: In most European countries, Salmonella is kept under control with preventative measures like vaccination. It is usually illegal to wash eggs, so an egg's cuticle remains intact and they don't have to be refrigerated.
Other Pros and Cons of Refrigeration
Even though you may not need to refrigerate your eggs, depending on where you live, you might want to.
This is because refrigeration can provide some benefits. However, it can also have drawbacks. Below are the pros and cons of egg refrigeration.
Pro: Refrigeration Can Double an Egg's Shelf Life
Storing your eggs in the refrigerator is the best way to keep bacteria under control.
As an added bonus, it also keeps eggs fresher for much longer than storing them at room temperature.
While a fresh egg stored at room temperature will start to decline in quality after a few days and need to be used within 1–3 weeks, eggs kept in the refrigerator will maintain quality and freshness for at least twice as long (, , ).
Con: Eggs Can Absorb Flavors in the Fridge
Eggs can absorb odors and flavors from other foods in your fridge, such as freshly cut onions.
However, storing eggs in their carton and sealing foods with strong odors in airtight containers can prevent this from being a problem.
Con: Eggs Shouldn't Be Stored in the Fridge Door
Surprisingly, where you store your eggs in the refrigerator can make a difference too.
Many people keep their eggs in the door of the refrigerator. However, this can subject them fluctuations in temperature every time you open the fridge, which could encourage bacterial growth and impair the egg's protective membrane ().
Therefore, keeping eggs on a shelf near the back of the refrigerator is best.
Con: Cold Eggs May Not Be Best for Baking
Lastly, some chefs claim that room-temperature eggs are the best for baking. Because of this, some suggest letting refrigerated eggs come to room temperature before using them.
If this is important to you, it is considered safe for eggs to be left at room temperature for up to two hours. However, you should be sure to cook them to a safe temperature afterward ().
Bottom Line: Refrigeration keeps eggs fresh for more than twice as long as eggs kept at room temperature. But they must be stored properly to prevent taste and temperature changes.
Do Eggs Need to Be Refrigerated?
It depends on where you live, since the way your country treats Salmonella determines whether eggs really need to be stored in the refrigerator or not.
In the US, fresh eggs need to be refrigerated. However, in many countries in Europe and around the world, it's fine to keep eggs at room temperature for a few weeks.
If you don't know whether the eggs you buy should be kept in the fridge or not, check with your local food safety authority to see what's recommended.
If you're still unsure, refrigeration is always the safest way to go.