Like all fresh foods, eggs don't last forever. But thanks to their shells, they're rather resilient. Even though the mandated USDA washing and processing of eggs actually reduces their oxygen barrier, shortening their freshness cycle, they still come with a relatively robust time allowance: eggs can be consumed 45 days from the time of processing (which is usually just a few days after being laid). But if you're still wondering how to tell if eggs are good or bad, read on.
How to tell if eggs are still good
The best way to know if an egg is still good is to go by the date code on the package that it came in. However, if you have an egg and are unsure about that date, another way to test it is to place it in a bowl or glass filled with cold water.
The water test for egg freshness
First, fill a bowl or glass with about four inches of cold water and gently place your egg(s) inside.
Very fresh eggs will sink to the bottom and lay on their sides. If an egg stays at the bottom but stands on its small end, it's still acceptable to eat; just not quite as fresh. These "more mature" eggs are no less nutritious than a fresher egg, and most people are unlikely to notice a difference in taste. Two bonuses: 1. They'll peel without sticking to the white when hard boiled and 2. The egg whites are easier to whip into meringue when making desserts.
Any eggs that are too old to eat and should be discarded will float to the surface. Once enough oxygen has had time to permeate the shell, it forms an air pocket large enough to keep the egg afloat in water.
How to tell if eggs have gone bad
Along with the water test, there are a few more quick ways to tell if an egg is good or bad.
If you crack open an egg and immediately notice a pungent smell, it's probably safest to toss the egg. When eggs develop cracks during handling and transportation, bacteria has a chance to enter through the shell and can cause some pretty stinky odors to develop inside the egg. On the other hand, fresh eggs tend to have little to no noticeable odor.
After you've cracked open an egg, look at the inside of the shell for black or brown spots, which can indicate mold. On the contrary, dark brown or red specks (blood spots) floating in the egg white or clinging to the yolk are not an indication of spoilage and are completely safe to eat or remove with a spoon.
Egg white consistency
As eggs sit in your fridge, a small amount of air slowly seeps through the shells over time, creating that air pocket you may have noticed when peeling a hard-boiled egg. This can cause the egg white to become watery. Although runny eggs aren't necessarily unsafe to eat, if you're unsure of the expiration date and notice that the egg whites are particularly loose, it's probably best to get a new carton.