The freshness of an egg can be determined by simple observation and testing. First, check the inside of the egg directly. If the egg is cracked open and the yolk is scattered and mixed with the white, emitting an unpleasant odor, the egg has gone bad and should not be eaten. On the contrary, if the yolk is spherical and slightly raised while the white surrounds it, this indicates that the egg is fresh. A slightly sunken yolk with clear and tightly packed whites may be slightly less fresh, but can still be eaten. If the yolk is spread out and the whites are like water, the egg is completely bad.

Second, you can perform a float test. Place the egg in cold water, which should be higher than twice the height of the egg. A fresh egg will sink to the bottom vertically, possibly in contact with the bottom of the bowl, but will not float. If the egg is tilted or standing upright in the water, it has been stored for a long time, perhaps a week or so. And less fresh eggs (about a week) will sink but will float slightly up and down. But once the egg floats in the water, it's a clear indication that the egg has gone bad and should be avoided.