It is difficult to ascertain the quality of the egg by looking at the outer shell; it doesn’t reveal the quality of the yolk inside.
The longer the storage time, the internal quality of the egg deteriorates, however the chemical composition of the egg (i.e., white and yolk) doesn’t change much.
Here are a few simple methods to test the quality of the egg:
To test the freshness of the egg, place the eggs in a wide open bowl with cold water and check where it stands.
If the egg lies at the bottom of the bowl horizontally then it is very fresh.
If it stands upright but still touches the bottom of the bowl it shows that the egg started aging but still can be consumed.
If the egg floats, its past its prime and not good for eating.
If it is vertical in position it has become stale and cannot be consumed.
If you are having a doubt on the freshness of the egg, do not use it, rather perform the test and decide for yourself to use these or not.