Expired eggs: toss them only if they don’t pass these tests

“Can you eat expired eggs?” is a very common question on every search engine and in every language in the world.
I appreciate very much that more and more people are concerned about not wasting such a precious and unique food as the egg; after all, there are few foods that contain so much protein, minerals, fatty acids, antioxidants and vitamins in such a small space.
However, there is little to cheer about, as the “many” people fighting food waste are still a distinct minority compared to the masses: the number of eggs destined for landfills is staggering.
The saddest thing about all this, is that with basic consumer knowledge we could have avoided much of the said plague.
That’s why I think it’s essential to teach these concepts in schools, to finally raise a waste-conscious generation, without risking intoxication.

Waiting for the “evolutionary miracle”, here’s the dry answer: expired eggs can be eaten even after the expiration date; certainly after cooking and provided that they have been stored in the refrigerator according to certain criteria: however, if you smell a particularly strong odor (typical smell of rotten eggs), you must throw them away, regardless of the date written on the package.

However, there are times when determining whether an egg has expired or not can be a real headache, especially if, like me, you never buy eggs at the supermarket but directly from the farmer (hoping they come from happy hens).
In a moment, you will find all the necessary information for all eggs, even those without a date printed on the shell.
But first, a necessary parenthesis about egg waste.

How egg waste happens and why it must be stopped

We throw away a huge amount of eggs every year: about 165 million in Canada, 200 million in the United States, and about 720 million in the United Kingdom.
Unlike other foods such as fish or fresh produce such as fruits and vegetables, most egg waste does not occur during processing, but mainly after purchase. This makes us consumers primarily responsible for the shameful 30 percent waste of this miracle called the egg[1].
The implications of all this are even more serious when it comes to food of animal origin: not only are we throwing away a nutrient-rich food, when malnutrition is unfortunately still a tangible problem (2 billion people are affected!), but we are also needlessly wasting a product whose production processes very often cause serious complications for the environment and cruelty to the animals involved.

To return to the causes of waste, nothing new under the sun:

– we buy more than we can consume because eggs from intensive egg-producing farms are too cheap, and wasting them confirms the infamous “easy come, easy go” philosophy;
– we do not know how to store them properly;
– we blindly trust the sell-by date;
– we ignore foolproof tests that can determine whether or not expired eggs are safe to eat.

When safety is mentioned in connection with eggs, Salmonella undoubtedly comes to mind.

What is Salmonella and how to avoid Salmonellosis (Salmonella infection)?

Salmonella is the most commonly reported bacterium responsible for food poisoning worldwide, and it is usually associated with eggs and egg products: although we speak in the singular, we are actually referring to a large group of bacteria with different names and characteristics.

Salmonella strains can contaminate eggs in 2 ways:

– The 1st is the best known, which is fecal contamination. Since it is commonly found in the intestines and therefore in the feces of chickens, the egg can be contaminated either by the feces on the shell or by entering the shell through the pores of the egg;

– The 2nd route is caused by the presence of a specific strain of Salmonella, Salmonella Enteritidis (SE). If the hen is infected with SE, the bacteria will be present in her ovaries, and thus in the eggs, long before they pass through the gut.
By knowing the risk, we can protect ourselves from poisoning, regardless of whether the eggs are expired or not, since SE can be present in very fresh eggs or even eggs that have not yet been laid!
Laboratory studies on Salmonella Enteritidis show that the bacterial load on the shell surface is inversely affected by storage time, while an increase in relative humidity favors bacterial survival[2].
Another strain of the Salmonella group, S. Typhimurium, has shown increased survival on the shell at 22°C, while analysis confirms that the bacterial load decreases with storage temperature at 4°C[3].

From these few lines, it is immediately clear that the best way to avoid salmonellosis is to keep eggs refrigerated.

Where to store eggs and why?

In the refrigerator
The risk of salmonellosis alone, as seen above, is enough to choose the refrigerator as the place of storage. But that is not the only reason.
It is no secret that eggs begin to deteriorate as soon as they are laid, and their overall quality (external and internal) inevitably decreases along with the nutrients; however, the process could always be slowed down thanks to the refrigerator, which remains the most effective way to curb the race to decay: microorganisms are not active at low temperatures.
In addition to providing us with low temperatures, the refrigerator extends the shelf life by another welcome action: thermal stability.
Eggs at room temperature are subject to temperature fluctuations, a condition that can cause condensation to form inside the shell, an excellent habitat for the growth of Salmonella Enteritidis and other microorganisms, pathogenic or otherwise.
If you’re still not completely convinced, let’s look at the results of a study conducted in Brazil: “…At the end of the 9-week storage period, eggs stored in the refrigerator had similar quality parameters to eggs stored at room temperature for only 3 weeks. In contrast, eggs stored at room temperature showed a more rapid deterioration from the first week…”[4].

Additional tips
– To avoid condensation, in addition to keeping them in the refrigerator, do not leave refrigerated eggs out of the refrigerator for more than 2 hours (consume them within 2 hours).
– To do things right, keep them in their carton for extra insulation and to prevent moisture from escaping into the refrigerator.
– And again, on the subject of moisture, keep the carton inside the refrigerator, but not in the door, although it is usually organized with proper egg cups!

Curiosity

But if refrigeration is the best way to preserve eggs, why do supermarkets sell them at room temperature?
Simply because it would be very expensive to keep eggs refrigerated, given the space it would take up in refrigerated counters; and then because they are not legally required to do so

Freezer
If you need much more time to use the eggs, you can store them in the freezer: break them into a small bowl, beat them lightly with a fork (just to mix the white with the yolk) and put them in the appropriate containers for freezing (remember to write the date and the number of eggs on them). In this way you will be able to keep them for a whole year.
To defrost, place the container in the refrigerator 12 hours before eating.

How to store eggs: washed or dirty?

Contrary to what you may think, it is not necessary to wash eggs; in fact, you should not wash them at all to avoid facilitating the possible passage of pathogenic bacteria (such as salmonella) inside the shell.
If you really cannot give up this habit, apply it only to eggs that you are going to consume immediately and strictly after cooking.
And it goes without saying that if you do wash them, you will be on the hook for sanitizing half the kitchen to avoid cross-contamination; as well as the entire sink, the faucet, the adjacent wall, and anywhere the water might splash – which is another reason to never wash them.
In any case, whether you wash them or not, you should wash your hands well with soap and warm water before touching anything else.
Similarly, it is advisable to regularly wash the refrigerator egg rack (if you use it) with soap and warm water.
Dirty farmer’s eggs can be wiped dry with a simple kitchen sponge, taking care not to apply too much pressure.

But do eggs expire?

Yes, of course, but almost never the same day as the date on the package. Let’s start by saying that the date on the package is not the day the egg becomes surely fatal or dangerous to your health.
Normally, if kept in the refrigerator at all times, we will still have excellent eggs even several days after expiration: to be used in preparations (I strongly recommend not to consume them raw; especially if the meal is intended for a child, pregnant woman or immunocompromised persons).

And if the egg has no date on the shell, because it is not part of the great distribution, how to determine if it is still edible?
Simple, by performing a float test (also valid for supermarket eggs that are certainly past their sell-by date).

What is the water test?

During storage, eggs begin to lose moisture from their shells over time, creating an air chamber.

The buoyancy test is used to determine the size of this air pocket:

– if the egg sinks, it means that the air pocket is still small; in other words, the egg is very fresh and its initial moisture is still intact;
– if the egg remains suspended, it is fine until it touches the surface of the water, it means that the eggs are fresh: the air chamber is forming, which indicates that they have been laid for a few weeks at most;
– if, on the other hand, it floats, the moisture has disappeared and the inner tube has reached a considerable size: the egg can no longer be called fresh; but… it is not necessarily toxic!

Translation: never throw away an egg just because it “floats”!

Let’s do some more tests instead: visual and olfactory checks are easy to perform.

Visual and smell inspections

The shell should be firm, not slimy (an indication of possible bacterial contamination), free of coloration that can be defined as abnormal (blue or green spots) and/or clear signs of mold: remember that the shell is porous and if air and moisture can pass through, bacteria and mold would be no different.
If everything is normal so far, you can proceed with cracking open the shell and looking inside.

It doesn’t need to be written down, but it’s better not to be left in doubt: don’t “crack” suspect eggs into a preparation with good ingredients inside; always use a separate small bowl so that you can discard only the incriminated egg, just in case.

Over the days of storage, certain physical changes occur in both the yolk and the albumen; it is therefore normal for the yolk to become flatter, its membrane weaker and the albumen more liquid and thinner.
Instead, if you notice a green or iridescent (changing colors) albumen, this may indicate the presence of Pseudomonas: discard it without further thought.
Similarly, the presence of Pseudomonas may be warranted by a pink or pearly albumen.
Salmonella, on the other hand, is invisible and odorless; but rest assured, as long as we do not consume raw, expired eggs, we are not at risk of infection.

Having passed the visual test, we move on to the smell test.
In the case of truly expired, i.e., rotten eggs, the olfactory test takes pole position: it is so persistent and unbearable that it renders any other test useless.
Normally, fresh eggs have no particular odor; if you smell something strange, unpleasant, or sweet and fruity, i.e., something that should not belong to an egg, throw it away without a second thought and be more careful next time.
But if you needed the egg to make a cake or meatballs or pancakes, well, I recommend you read the article on egg substitutes.

If your egg passes this test as well, you can move on to tasting; assuming you cooked it properly: Salmonella and many other pathogens die instantly at 74 C degrees. So no runny, sunny side up or soft-boiled eggs; no tiramisu (even if you pasteurize it) and not even soft scrambled eggs.
You must cook them until they are perfectly firm.

One last but valuable tip for you: old eggs are great for hard-boiling, easy to peel; and even for meringues.

In conclusion, expired eggs can be eaten after the expiration date (with proper precautions), but to limit waste and get all the nutrients at the highest level, next time buy only the ones you can consume.

Happy Revolution to you all

Bibliography
1) Carla Caldeira, Valeria De Laurentiis, Sara Corrado, Freija van Holsteijn, Serenella Sala,
Quantification of food waste per product group along the food supply chain in the European Union: a mass flow analysis, Resources, Conservation and Recycling, Volume 149, 2019, Pages 479-488,
2) Messens, W et al. “Eggshell penetration of hen’s eggs by Salmonella enterica serovar Enteritidis upon various storage conditions.” British poultry science vol. 47,5 (2006): 554-60
3) McAuley CM, et al. Salmonella Typhimurium and Salmonella Sofia: Growth in and persistence on eggs under production and retail conditions. Biomed. Res. Int. 2015;2015:914987
4) Feddern, Vivian, et al. “Egg quality assessment at different storage conditions, seasons and laying hen strains.” Ciência e Agrotecnologia 41 (2017): 322-333

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