Old eggs float in fresh cold water because of a large air cell that forms as the egg cools after being laid. As the egg ages, air enters the egg and the air cell becomes larger and this acts as a buoyancy aid. Here is a test for eggs:
Carefully lower your eggs into fresh cold water (do not use salted water) using a spoon:
- If the egg stay at the bottom - it is fresh.
- If the egg is at an angle on the bottom - it is still fresh and good to eat.
- If the egg stands on its pointed end at the bottom - it is still safe to eat but best used for baking and making hard-cooked eggs.
- If the egg float - they're stale and best discarded.
The final test: To make sure the egg is not spoiled, break it into a clean bowl and check to make sure it doesn't have a bad odor or appearance.