It’s hard to tell just by looking at an egg whether it is fresh or not and sell-by dates are merely a suggestion. Depending on how the egg was shipped and stored, the sell-by date may hold no bearing on how fresh the egg truly is. Here are a few methods for testing an egg’s freshness.
The Water Method
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 increasing size of the egg’s air cell as it ages.
Examine the Whites
This method requires cracking an egg open but it’s a good way to test a carton of eggs that you may have forgotten about in your refrigerator. Crack an egg 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 clear and watery.
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.