Is It Safe to Eat Grey Eggs? Answers and Facts


Fresh eggs should have a beautiful clear egg white and a golden yellow yolk when they’re cracked fresh from their eggshell. But boiled eggs can be a different story. Sometimes boiled eggs appear to be grey inside and have somewhat of a green ring where the white and yolk meet. Is it safe to eat grey eggs?

boiled egg appetizers
boiled egg appetizers

What Causes Eggs to Turn Grey?

A chemical reaction that occurs when hard-boiled eggs are cooked too long or at high heat is what causes a grey color or green ring to appear around the egg yolk, leading into the egg white of some eggs.

You won’t necessarily see the change in color in scrambled eggs, hard-cooked eggs, or poached eggs, depending on your favorite method for cooking eggs. It mainly happens in boiled eggs and presents itself as a greenish gray color.

Next, we’ll explain why this chemical reaction causes a change in color of the egg for this cooking process.

Why Do Overcooked Eggs Have a Grey or Dark Black-Green Layer Between the Yolk and the White?

Why this change occurs is because of the different chemicals that are in the egg yolk as compared to the egg white.

The iron in the yolk mixes with the hydrogen sulfide in the egg white when the egg is boiled too long. It naturally forms ferrous sulfide at the surface of the yolk.

boiled eggs various colors
boiled eggs various colors

After the eggshell is removed and the egg is cut into, the color of the yolk or the surface of the yolk might appear to be a grey egg yolk.

As long as no other key indicators of spoilage are present, the good news is this is a safe egg to eat.

How to Make the Perfect Hard-Boiled Egg

When cooking boiled eggs, it’s important to be sure that they’re cooked long enough, but not too long so as to avoid that grey or green ring from forming around the egg yolk.

Begin by boiling a saucepan with water. Once the water has reached a rolling boil, carefully add your eggs.

Allow the eggs to continue to boil for the specified time.

Small Eggs: 8 minutes for a firmly hard-boiled egg

Medium Eggs: 9 minutes for a firmly hard-boiled egg

Large Eggs:  10 minutes for a firmly hard-boiled egg

Boiled egg in metal stand
Boiled egg in metal stand

Soft-boiled eggs can be cooked for as little as 3 minutes for a really soft boiled yolk and set white.

After the eggs are finished boiling, run them under cold water or place them in a bowl of ice water until they’re completely cooled.

If you want to use them right away, you can remove the egg shells and prepare them to be served.

Or if you want to store them for later, you can leave the egg shells intact and transfer the cooked eggs to the refrigerator for storage.

Is It Safe to Eat an Egg With a Grey or Green Ring Around the Yolk?

Yes, typically the green or grey ring around the yolk in boiled eggs is caused by a chemical reaction and is the result of the egg being overcooked.

If there are no other key indicators of spoilage present, likely the egg is safe to eat.

How Do I Know if My Grey Egg is Too Old to Eat?

If the boiled egg has been stored in the refrigerator for more than 7 days or if it has any of the other key indicators of spoilage, it’s too old to eat.

If you think your eggs have spoiled, don’t risk eating them. Throw them away instead.

close up view of eggs in carton
close up view of eggs in carton

What Does the Color of the Yolk Tell Us?

There are some potential conclusions that can be drawn from the color of the egg yolk. The color of the egg doesn’t usually affect the nutritional value, however.

Deep Yellow Color

A deep or dark yellow color is usually an indication that the hen is healthy and has been fed a varied diet.

Pale Yellow Color

A pale yellow egg yolk color usually shows that the hen as not as varied in her diet. It doesn’t mean that nutritional value has been compromised.

Can I Tell From the Outside of the Egg if It Will Have a Grey Yolk?

No, there’s not really a good way to tell from the outside of the egg if the yolk will be grey. Even if you were to crack the egg open, the egg might appear to be fine.

It’s not until after the egg is boiled that the chemical reaction takes place that makes the egg turn grey.

boiled eggs on toast
boiled eggs on toast

Does the Storage of the Egg Before Cooking Affect the Color of the Egg?

According to the American Egg Board, the storage of the egg before cooking it can affect the color of the egg.

For example, the length of time the egg is stored can affect its color. This means that the longer the egg is stored, the lighter the yolk becomes.

It can also mean that if the egg is stored too long, the egg can spoil. This can also affect the color and compromise quality from what it should be.

Grocery store eggs that are stored at room temperature for too long can become green eggs and can potentially cause e. coli if consumed.

How to Avoid the Eggs Turning Grey?

To keep your boiled eggs from turning grey, it’s best to keep your eggs from overcooking, plus help them to cool quickly.

This can be done by running cold water over them or by placing them in a bowl of ice water until they’ve had a chance to completely cool.

After the eggs have cooled, keep them in their shells and place them in the refrigerator until you’re ready to use them.

brown eggs in a wood bowl
brown eggs in a wood bowl

How Long Can I Keep Boiled Eggs That Are Grey Before Eating Them?

The aspect that they’re grey is probably not harmful if the eggs are boiled, it usually just indicates that they’re overcooked.

Like any other boiled egg, they can be kept in the refrigerator in their shells for up to seven days.

How Long Are Boiled Eggs Good For?

You can keep boiled eggs in the refrigerator for up to 7 days. After the 7 days have passed, if they’ve not been used, they should be thrown away.

How to Correctly Store Boiled Eggs

The best way to store boiled eggs is in their shell in the refrigerator. This will help to keep other flavors and smells as well as bacteria sealed out of them and will ultimately help to lengthen their shelf life.

brown eggs in a wood bowl
brown eggs in a wood bowl

The United States Department of Agriculture recommend taking eggs straight home and putting them in a refrigerator set to 40F degrees or below.

Keep them in the coldest part of the refrigerator and not on the door.  

How to Know if Eggs Go Bad

There are a few ways you can look for key indicators that your eggs have gone bad. You can use your senses such as taste, smell, and appearance. Or you can also use the raw egg test if your egg has not yet been cooked or cracked open.

The Raw Egg Test

You can test whether your eggs are still good by using the raw egg test. To do this you should use a whole egg that’s still in its shell that’s not yet been cooked.

Just fill a bowl with cold tap water and carefully place the eggs in the water.

If the eggs sink to the bottom of the bowl, they’re still good.

If any of the eggs float, those old eggs are bad because they’ve formed an air pocket. They should be thrown away.


If you notice a color change in your eggs, especially a pink color pearly egg white, or one that’s green in color. This indicates spoilage due to pseudomonas bacteria, which is harmful to humans.


If you crack a raw egg open and notice that it smells strange or if you notice that your cooked eggs smell off, you’ll not want to risk eating them.

boiled egg on cutting board
boiled egg on cutting board


The same is true about the flavor of your eggs. If they don’t taste right, then don’t eat them. Flavor can also be a sign of spoilage.

If you suspect that your eggs have gone bad, you should not risk eating them, and you should throw them away instead. Eating food that has gone bad can potentially cause food poisoning from harmful bacteria and make you sick.

Frequently Asked Questions

Following are frequently asked questions that relate to is it safe to eat grey eggs. If you have a question that’s not answered here, feel free to drop it to us in the comments box below and we’ll be happy to answer it.

Why did my eggs turn grey?

Hard-boiled eggs turn grey when they’re overcooked. It causes a chemical reaction which results in a greenish-gray ring around the egg yolk between the egg white.

Why do eggs go grey in the fridge?

Chances are if your eggs go grey in the refrigerator it’s probably because they’ve been boiled and have been cooked for too long and a chemical reaction has taken place.

If raw eggs go grey in the refrigerator, it’s likely they have reached or gone past their expiration date.

boiled eggs in a green bowl
boiled eggs in a green bowl

What color is an unhealthy egg?

A healthy egg white will be clear or a cloudy white when its shell is cracked open. The same is true with a healthy egg yolk. It should be a nice yellow yolk or a yellow orange color.

On the other hand, if the egg is any other color besides what it should be, it’s probably a rotten egg, and should be thrown away. An unhealthy egg can be green, iridescent, pink, or even black. It promotes an unpleasant odor.

Can I eat a grey omelet?

As long as the egg white or egg yolk are not grey when you crack them open, it’s probably okay.

You’ll want to check the appearance, smell, and flavor. And if any of those are off, you’ll want to throw it away.

An egg that has been scrambled, such as is the case with an omelet undergoes a chemical reaction that can cause it to appear grey.

Can I cook eggs in a cast iron pan?

Yes, frying or scrambling eggs in a cast iron skillet is a great way to cook them for delicious flavor.  It shouldn’t discolor your eggs.

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Sarah is known for her extra fancy yeast breads, melt in your mouth pies, and everything salads. She has won awards as a home cook, and is passionate about helping others feel smarter in the kitchen. Sarah is the cooking genius of the sister duo.

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