In fact, most eggs will keep well in the refrigerator for weeks after the date stamped on the carton. But you can't always rely on your eyes and the printed date to tell if an egg is spoiled or not, and the nose can't always tell how fresh and edible an egg is.
Because eating a rotten egg can cause severe food poisoning, it's best to be sure of its expiration date before you decide to throw it away just because it's expired.
1- Egg float test
To find out if the eggs are safe, you can put them in a cup of water to test whether they sink. Place the eggs in a bowl and cover them with cold water. If the eggs sink to the bottom and lie flat on their side, they are still fresh and edible.
But if the eggs float to the surface, or part of them is in the water and another is on the surface, then they are not edible. The science behind this is based on the fact that eggshells have semi-permeable properties, which means air can pass through. So the older the egg gets, the more air can penetrate its shell, causing it to float.
2- Shake the eggs test to see if the eggs are spoiled
Another method, but not as reliable as the float trick, is to hold an egg and shake it near your ear. If you hear liquid oozing inside, the yolk is old and watery and the egg is bad.
On the other hand, if there is no sound, that is good news that the egg is healthy and edible!
3- Smell the egg to see how long it lasts
If the egg does not pass the odor test, it is best to discard it. Eggs have a neutral odor, but the smell observed such as the smell of sulfur or acid gases is a sign of spoiled eggs.
4- Use your eyes to see how long the eggs last
Finally, as a last resort, you can use your eyes to examine the crust. If it has cracks or a sticky or powdery exterior, it is likely to be contaminated with bacteria or fungus.
In the event that the egg is boiled, a good and fresh egg is characterized by its yellow or light orange yolk, and the white is bright white and coherent around the yolk to the degree of perfection.
As for the spoiled or inedible, the white is of a fluid consistency and may be more spread out.