How to Do the Egg Float Test, According to a Chicken Farmer

My family raises chickens and I love having eggs readily available. But egg management is a big deal, even farm-fresh eggs can go bad. As a chicken farmer, I’ve learned the hard way. If you’ve ever cracked a bad egg, you know that the smell is horrific. Nothing brings on a spell of gagging quite like a rotten egg.

How do you avoid this brutal nasal assault? A quick Internet search suggests an egg float test. But is the egg float legit? We turned the “eggs-perts” to tell us if the test is valid. Plus, they provide tips on how to keep eggs fresh longer.

What is the egg float test?

One method we’ve used to test the freshness of our eggs is the egg float test. My kids (the egg overseers) will fill up a big bowl of water and test away. Bart Slaugh, PhD, director of quality assurance at Eggland’s Best, says it works, and explains how to do it:

“To test your egg, gently rest it in a cup of water. If the egg is fresh, it will sink to the bottom of the cup. Additionally, its length will remain flat against the bottom. If your egg does not remain flat against the bottom of the cup but rather rears up at one of its ends, it is only semi-fresh. The less fresh your egg is, the more it will float. If the entire egg floats to the top quickly, that is a very bad sign as far as quality goes.”

How in the world does putting an egg in water determine its freshness? “Since eggshells are porous, eggs lose moisture from inside during storage. The interior contents shrink and create an air cell in the large end of the egg. This makes an egg increasingly more buoyant the longer it is stored. Buoyancy can, therefore, give a general indication of how old an egg is,” Slaugh says.

But you don’t have to dump all those floating eggs in the trash. A floating egg may still be safe to eat. “It is important to note that this is a test of freshness and not a safety test. As long as eggs are kept properly refrigerated, eggs will simply dry up during extended storage, rather than spoil or become unsafe,” Slaugh adds.

What are other ways to tell if eggs are fresh?

Aside from the egg float test, there are some other easy ways for you to evaluate the quality of your eggs.

“To determine if an egg has gone bad, you can crack it open and smell it, and check for visible signs of contamination. A spoiled egg will give off a foul odor when cracked open and will be present even after cooking the egg. You should discard eggs with any visible signs of contamination, which include cracks in the shell, a powdery substance on the shell, or a shell that looks or feels slimy,” says Shelley Balls, RDN, a registered dietitian and nutritionist for Consumer Health Digest.

Slaugh says when you crack a good egg, the yolk should be perfectly distinct from the white so much that if you use your hands to separate the two components, you will find that no yolk invades the white.

How long do unwashed eggs last?

Store-bought eggs have been washed and sanitized, but farm-fresh eggs may be unwashed. When eggs are laid, they have a protective coating—the bloom or cuticle—that seals the egg and prevents penetration of bacteria.

Whether or not you wash the bloom off is up for debate. Those who prefer farm-fresh eggs like the fact that the eggs have a natural seal—no sanitizing solution required. Additionally, proponents of keeping the bloom intact say that the eggs last longer. But research doesn’t seem to support this particular notion.

“Unwashed eggs stored at room temperature can last over two weeks, but the main concern is how rapidly the egg quality degrades each day. One study¹ found that unwashed eggs stored at room temperature degraded from Grade AA (freshest and highest quality eggs) to Grade B (used for liquid egg products) in just one week. This study also revealed that refrigerated eggs, regardless of whether they were washed or oiled (mineral oil application after washing), were still Grade A quality after 15 weeks,” Balls explains.

For large egg producers, it makes sense that washing would be the norm. Retaining top quality is important for overall consumer satisfaction and safety.  “In the U.S., it is considered safest to clean and sanitize eggs, even though the natural cuticle covering is partially removed in the process. Washing eggs helps to reduce the risk of cross-contamination when eggs are handled during meal preparation,” Slaugh says.

How to keep eggs fresh as long as possible

If you’re anything like me, you’ll use a ton of eggs one week, but then the next, your eggs get tucked into the back of the fridge, untouched. How do I get my eggs to last longer? Proper refrigeration is the answer.

According to the USDA, raw eggs in the shell last in the fridge for three to five weeks. “After eggs are refrigerated, they need to stay that way, so you wouldn’t want to buy eggs from the refrigerated section of the store and bring them home to be stored at room temperature. A cold egg left out at room temperature can sweat, facilitating the movement of bacteria into the egg and increasing the growth of harmful bacteria,” Balls says.

The same goes for farm-fresh eggs. If they were refrigerated, they must stay that way. So get those eggs into the refrigerator ASAP. In addition, you may also want to store your eggs near the bottom of the fridge. “Lower shelves are generally cooler than the door, which can experience more refrigerator temperature changes and jostling,” Slaugh suggests.

Finally, Slaugh gives one last pro-tip for better-tasting eggs: “Keep your eggs away from strong-smelling foods.” Because of their porous shells, eggs can pick up the flavors of the things around them. So separate them from your fish, garlic, or onions to prevent flavor changes.