There are two main ways to tell if an egg is still good:
Check the Expiration Date: In most countries, eggs come with a “sell-by” date printed on the carton. This date indicates the last day the store should sell the eggs for the best quality. The USDA (United States Department of Agriculture) considers eggs safe to eat for 45 days after the date they are processed (which is usually a few days after being laid). So, the sell-by date gives you a good idea of when the eggs are likely to be freshest.
The Water Test: This is a simple at-home method to assess an egg’s freshness. Fill a bowl or glass with cold water and gently place your egg(s) inside. Here’s what the results mean:
- Sinks flat on its side: The egg is fresh.
- Sinks on its end: The egg is not as fresh but still edible.
- Floats: The egg is likely not fresh and should be discarded.
The science behind this involves the air sac that forms inside an egg as it ages. A fresher egg has a smaller air sac, making it denser and sink flat. As the egg ages, the air sac gets bigger, causing it to float.