Most of us in the United States do not, and never have, lived on farms, so the only time we see eggs are when they’re cold and delivered to our grocery store. But if your refrigerator dies on you, or you’re at a farm, you may be wondering, how long can eggs stay unrefrigerated before they go bad?
Well, the general rule of thumb for an egg in the fridge is that you probably shouldn’t eat it if it’s been out for more than a day or two. But eggs overall are a little more complicated than that. When they are first laid by the chicken, they come with a natural coating on them, an antibiotic coating that helps keep them safe from disease and actually makes the shell harder for bacteria to get into. This coating washes off when the eggs are cleaned, as they must be to sell in the grocery. So an egg right from the farm can easily last longer than the couple days window that we have to give to an egg out of the refrigerator.
Also, when an egg is put in the fridge and then taken out, as it warms up it absorbs moisture
from the air. If the egg was not properly cleaned before being refrigerated that could lead to the egg absorbing some of the bacteria or dirt on the egg itself. This may not cause a problem if you cook the egg thoroughly, but it will make the egg spoil faster.
There is an easy way to test how healthy an egg is. As eggs age they lose water, and a small air sack starts to enlarge inside the egg. An egg with a large enough air sack will float if put into a bowl of water. So put the egg in some water, and if it floats, toss it.
But thankfully, the protein in raw eggs lasts for quite a while – it is, after all, meant for a chick to live off of in the weeks that the egg matures, so the egg is a pretty resilient thing. Ironically though, the process necessary to approve them to sell in the United States also drastically reduces their lifespan. So the only safe answer for an egg from the grocery store is to give a warm egg no more than two days, and even then, test it in a bucket of water before eating it.