It is hard to tell just by looking at an egg whether it is fresh or not, and since the sell-by date stamped on the container is merely a suggestion it still leaves room to question—depending on how the egg was shipped and stored, the sell-by date may hold no bearing on how fresh the egg truly is. But don't toss out those eggs just yet! Here are three methods you can use for testing an egg’s freshness.
See if it Floats
With simply a glass and some water, you can determine the freshness of an egg. Fill a large glass with water and place a raw egg inside. If the egg sits at the bottom on its side, the egg is very fresh. If the egg sits at an angle or stands on one end, the egg is older but still edible. If the egg floats, it should be discarded. This phenomenon is due to the fact that the shell is porous and allows air to flow through, increasing the size of the egg’s air cell as it ages.
Examine the Whites
This method requires cracking open an egg but it is a good way to test the freshness of that carton you may have forgotten about in your refrigerator. Crack one of the eggs onto a flat surface (a plate or fry pan) and examine the consistency of the whites. If they are viscous, don’t spread much, and slightly opaque, the egg is very fresh. If they are clear, watery, and spread out widely, the egg has aged.
As an egg ages, the whites begin to break down and become transparent and liquidy. The yolk will also appear slightly flattened on top instead of round.
Take a Sniff
Another simple way to screen “bad eggs” is to give them a good sniff. A rotten egg has a very distinct and unpleasant sulfurous smell. Sometimes the scent is so strong it can be smelled through the shell.
Otherwise, the smell should be noticeable as soon as the egg is cracked. Any egg with an off-putting smell should not be eaten.
What to Do With Less Than Fresh Eggs
As mentioned above, just because an egg has a larger air cell or has slightly runny whites does not mean that it cannot be eaten. In fact, eggs that are slightly older are great for hard-boiling. The larger air cell and break down of the membrane make for easily peeled hard-boiled eggs. Once the eggs are boiled, store them in the shell until eaten or up to one week.
And don't forget about the shells and carton! The egg shells are great to add to compost and soil for their nutrients, and can also be used to make sidewalk chalk and clean your teapot. The egg cartons can be made into bird feeders, candle molds, and are great fire starters (but not the styrofoam ones!).