Why is My Egg Yolk Black?

Cracking an egg open to find a black egg yolk can be extremely startling. It’s also possible to occasionally find a black spot in egg yolk.

But what exactly causes egg yolks to turn black, and are there any instances where black egg yolks are safe to consume? Let’s delve deeper into this intriguing culinary phenomenon.

When eggs are hard-boiled and overcooked, the yolk may form a greenish or greyish layer around it. This discoloration is primarily due to chemical reactions between the iron in the yolk and sulfur in the egg white, and it’s not harmful to consume.

Overcooking, however, is just one of the factors that can contribute to black egg yolks. A very overcooked hard-boiled egg may even turn black and still be safe to eat.

But a raw egg with a black yolk is a bad egg and should never be eaten. While this may look unappetizing, it generally poses no health risks. However, a raw egg with a black yolk is a bad egg and should never be eaten.

Read on to learn more.

egg yolk black

What Does it Mean When Egg Yolk is Black?

An egg yolk turns black when the egg is rotten.

Therefore, a raw egg with a black yolk, or black specks inside the egg, should never be eaten and should be discarded immediately.

Egg yolk may turn black for several reasons, but none are good.

Here are the leading causes of black egg yolks.

The Egg Is Rotten

Egg yolks turn black when rotten due to the decay of the minerals inside the egg when exposed to oxygen.

An egg with a black yolk will also smell extremely bad.

The Egg Is Contaminated With Bacteria or Fungi

If an egg has grey or black spots and streaks inside the shell, it’s probably due to a fungus or bacteria contamination.

If you have a raw egg with a black yolk, discard the egg and don’t eat it.

An egg that has spoiled or gone bad is easy to detect because it has a strong unpleasant smell.

However, an egg that is contaminated may not always have an equally strong smell; discard an egg with black or grey spots or streaks, even if it does not smell bad.

An egg may have a red spot on the yolk or in the white.

This red spot may appear dark in color, as a rusty or brown color.

It’s called a blood spot or a meat spot and is safe to eat.

The spot may be dark in color but shouldn’t be black. If there’s a black spot in the egg yolk, discard the egg and don’t eat it.

Is Black Egg Yolk Safe to Eat?

There are only two types of black egg yolk that are safe to eat:

Overcooked Hard-Boiled Eggs

If you have severely overcooked a hard-boiled egg, especially if you have hard, mineral-rich water, the yolk will develop a green color, then grey, then black.

On the other hand, if a hard-boiled egg has a black yolk but otherwise smells normal, it’s probably safe to eat.

Century Eggs

Century eggs are a traditional food in China, where raw eggs are preserved in a coating of clay and ash for several weeks or months.

As the century egg ages, the yolks turn dark green, grey, or black, and the white turns a translucent brown.

The clay coating prevents oxygen from entering the eggshell, preventing bacteria and spoilage, while the chemicals in the egg break down, naturally producing salts and other flavors.

These are the only two instances where a black egg yolk is safe to eat.

In all other cases, eggs with black yolks should be discarded, especially if the egg has a strong, unpleasant smell.

What Happens if You Eat Black Egg Yolk?

If your egg yolks have turned black because of over-boiling, nothing will happen when you eat them.

If you have black eggs because the egg is bad, then eating a black egg yolk may cause:

  • Diarrhea
  • Stomach pain
  • Stomach cramps
  • Vomiting
  • Fever
  • Headaches

The primary risk of eating rotten eggs is the risk of contracting salmonella. Salmonella is a potentially severe bacterial infection that can lead to gastrointestinal distress and other health complications.

If you have salmonella, symptoms typically appear within 12 hours and grow worse over the next 48 hours, occasionally causing an itchy rash and other symptoms.

Salmonella is not usually fatal to healthy adults, but about 15% of healthy adults who contract it die from complications.

Salmonella can be extremely dangerous for young children, the elderly, pregnant women, and people with other health conditions.

Black Egg Yolk Superstition

Over the years, many myths and superstitions have grown around black egg yolks and their meanings.

Here are some of the most interesting superstitions about black egg yolks.

Superstition #1

Eggs were once used to tell fortunes, and a black egg yolk was a bad omen or sign of misfortune ahead.

Superstition #2

Eggs are a popular symbol of spring, renewal, and rebirth.

On the other hand, a black egg yolk was interpreted as a sign of impending evil or dark forces about to emerge.

Superstition #3

Eggs have also often been used in spiritual cleansing rituals, which absorb a person’s energy.

If an egg has been used this way and then is cracked to reveal a black yolk, it means that someone has placed an evil eye on you, while black spots inside an egg indicate illness and disease.

Superstition #4

A dream of a black egg yolk indicates that emotions are rising to the surface, that the unknown will soon be revealed, and that you feel unprepared or insecure about the new situation.


Can the breed of the chicken influence the likelihood of red yolks or blood spots?

While the article mentions age, stress, genetics, and nutrition as factors, it doesn’t specify if certain breeds are more prone to this than others.

Do cooking methods affect the visibility or taste of red yolks or blood spots?

The article states that there’s no difference in flavor, but it doesn’t mention if cooking methods (like frying vs. boiling) can change the appearance or taste.

Are there any health benefits or drawbacks to consuming eggs with red yolks compared to regular yellow yolks?

The article mentions safety but doesn’t delve into potential nutritional differences or health implications.

How can consumers reduce the chances of getting eggs with blood spots when purchasing from stores or local farmers?

The article explains the occurrence rate but doesn’t provide tips for consumers to minimize encountering such eggs.

Is there a difference in the shelf life of eggs with red yolks or blood spots compared to those without?

The article mentions that a red spot indicates a very fresh egg, but it doesn’t specify if this affects the overall shelf life.

In Summary

From ancient myths and superstitions to the modern day, a black egg yolk is never a good sign. It is crucial to exercise caution when encountering eggs with black yolks, as they are typically an indicator of spoilage or contamination.

If you crack an egg and find a black yolk or black or grey spots, discard the egg and don’t eat it. Food safety should always be a priority when handling eggs.

However, if you overcook a hard-boiled egg or encase an egg in clay and leave it for several months, turning the yolk black, it’s safe to eat.

When in doubt, always discard a questionable egg.

Eggs are usually quite affordable, and it’s not worth risking your health and safety for the sake of an egg.

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