A carton of eggs can sit in your fridge for a long time, even going beyond the projected expiration date. While expiration dates provide a ballpark estimate of when the product will go bad, it's not a guarantee. The Food and Drug Administration reports that eggs stored at 40 degrees or cooler typically are the best quality within three weeks of the purchase. Yet even that rule is vague because it doesn't necessarily mean the eggs have gone bad after three weeks -- it simply states that the quality has begun to reduce over time.
Eggs that have truly gone bad will start to decompose due to mold or bacteria. While this is the most obvious sign that an egg's lifespan is up, there are signs that an egg is going bad long before it's blatantly visual -- the amount of air in an egg increases as it begins to go bad, as well as a nasty stench that comes from the egg. Of course, this can be hard to spot just by looking at its shell, so how do you know for sure if an egg has gone bad? Check out these four methods to tell if your eggs are still good to eat.
Something rotten is often said to "smell like a rotten egg." and that simile didn't come from nowhere. Rotten eggs have a notoriously putrid smell, denoting that bacteria has taken over inside the egg. The easiest and least time-consuming method of finding out if your eggs are still edible is by smelling them. Along with being simple, the smell test is also the most reliable method of checking your eggs. If everything smells fine through the shell, generally the eggs should still be usable. If smelling through the shell still leaves you unsure, crack the egg into a bowl first and then smell it. If it smells off in any way, usually with a sour or sulphuric scent, that's an indication that you need to throw the eggs away.
Sometimes you can tell that an egg has gone bad just by looking at it. If the egg has any cracks, slime or a powdery substance on its shell, this is an indicator that bacteria has penetrated the shell and the egg is no longer safe to eat. If you're still worried your eggs might be bad after looking at them and seeing nothing worrisome, crack the egg into a bowl. Discoloration in the yolk or the whites, including black, pink, blue or green coloring, means it's time to throw the eggs away.
Eggshells have pores, meaning that even if the egg isn't cracked, there is room for the liquid inside the egg to evaporate through its shell and for air to enter as a replacement. The more liquid that has evaporated and allowed for air to replace it, the lighter the egg becomes. This means that eggs that float have likely spoiled, while eggs that sink are likely still good to eat.
Check if your egg floats by filling a bowl with clean, cold water and placing an egg in the bowl. If it sinks, that means it is still fresh and you can eat it. If it sinks, but it is standing up on its point, this means the egg needs to be eaten soon. If the egg floats, toss it because it has gone bad.
You should do this individually with each egg in the carton if you're not sure if they're safe to eat. Just because one egg is bad does not mean they all are.
However, if the eggs pass the float test, but then you crack them and notice an odd coloration or smell, that means the egg is probably rotten and should be thrown away.
This is a test that was initially used to check an egg's fertility, but it also works for checking its freshness. To perform this test, you will need a very dark room and a candle or flashlight. Shine the light directly next to the long side of the egg so you can see what lies beneath the shell. If an egg is fresh, its contents will fill the shell completely. If you see space within the shell, the egg is not fresh. The less the contents of the egg fill the shell, the worse shape the egg is in. Throw the egg away if it has a large air pocket to avoid eating a rotten egg and getting sick.
If you're not exactly sure if the egg's contents fill its shell, check to see how much the yolk moves around. Fresh eggs will have yolks that remain fairly stationary because it has a small amount of airspace. Old eggs that may have gone bad allow the yolk to move around a bit more.
Some old eggs might have bacteria in them even though they smell and look just fine. Be sure to cook these eggs thoroughly, and try to avoid extra runny or soft-boiled techniques when working with these older ones.
If you have a large number of eggs that you think are about to go bad, cooking them all and using them in later dishes allows you to kill off bacteria and prolong the overall life of the egg. Try hard-boiling the eggs and storing them in the fridge for use in a Cobb salad. Hard-boiling and deep-frying eggs is also a great way to keep them safe to eat while also providing a nice crunch.
Pickling eggs is also a great method for preserving eggs that are about to go bad -- by hard-boiling and then curing eggs in a brine of vinegar and spices, you can prolong their lifespan by months. The flavor also makes them a wonderful choice for hors-d'oeuvres, as well as being a nice addition to meat and cheese boards.
It's important to keep your eggs in a consistently cold environment, so be sure to keep your fridge at the right temperatures. You do not want your eggs to be stored above 45 degrees, as they will go bad at an exponentially quicker rate. It's also important to not keep your eggs on the fridge door -- while a convenient spot, it's also the warmest part of your fridge, meaning your eggs might not be staying at the proper temperatures to ensure their longevity.