The shell complicates things. As long as it’s not cracked, you have no idea what’s going on inside. And when an egg goes bad and is cultivating bacteria, it goes really bad (how ’bout a little salmonella poisoning?). So, whether preparing your protein over-easy, hard-boiled, or scrambled, how can you separate the bad eggs from the good?
First, let’s check the date on the carton. It may be labeled “SELL BY” or “BEST BUY” or “USE BY” or “EXP” (expiration). In any case, in America, it must be no more than 30 days from the “pack date” (the day the eggs were washed, graded, and packed). Check your laws in other countries.
The more-precise pack date is also on the carton (usually to the right of the packing plant number), but it’s a code you need to crack. That’s because it’s a Julian date, meaning it corresponds to a chronological day of the year: 1 (January 1st) to (non-leap year) 365 (December 31). Check a Julian calendar to figure this.
If properly refrigerated (not in the door’s egg compartment, but on a shelf in the colder main part of the fridge), eggs should be good for at least five weeks after their Julian date—and perhaps for even longer. Don’t toss any eggs simply because its expiration date has passed. Conversely, a great way to save on eggs is to buy them at a bargain price at or just after their “SELL BY” date.
THE FLOAT TEST
Because eggshells are porous, the liquid inside evaporates and is replaced by air. So, the older an egg is the more buoyant it is. Place a fresh (heavier) egg in a glass or bowl of cold water and it sinks to the bottom and lies on its side. An older (lighter) egg floats to the top, and should be discarded because the additional air is a bacteria breeding ground. Eggs that stand upright but don’t make it to the top are losing freshness and should be eaten soon.
Check your eggs before purchasing. A crack, because it lets air in, is a “Don’t Buy” sign, and so is any visible sliminess or mold or any sharp odor. And if an egg cracks once it’s bought, use it that day or freeze the contents.
Once you crack the egg into a bowl, look for any unusual discoloration: blue, green, or black. Because this probably indicates bacterial growth, throw that egg out. (A blood spot, on the other hand, is perfectly safe.) A thin and runny white and/or a pale yolk indicate the egg has lost freshness (or was always low grade) and won’t have a premium texture or taste when cooked, but it’s still edible if it doesn’t smell.
Sniff the raw egg. A healthy egg will have virtually no odor. A rotten egg will reek. Any unpleasant smell is a reason to chuck the egg. But don’t chuck the whole dozen yet. Individual eggs can go bad and not contaminate their neighbors.
Assuming it’s cleared the preceding gauntlets, it’s a good egg. And now it’s breakfast time—the taste test.