Drop the egg in a bowl of cold water. Fresh eggs sink and lay flat. Older eggs stand up. Spoiled eggs float. It works because the air cell inside grows as the egg ages.
Test 1: the float test
Fill a bowl with cold water and add the egg.
Test 2: the crack test
Crack the egg into a small bowl. Fresh: thick white close to the yolk, tall round yolk. Older: white spreads and thins, yolk flattens. Bad: sulfurous smell.
Test 3: the shake test
Hold the egg to your ear and shake it. A fresh egg is silent. An old egg sloshes because the contents have shrunk away from the shell.
When "old" is fine
Two-week-old eggs peel easier when hard boiled. Slightly older whites whip fluffier for meringue. Save the freshest for frying and poaching.
