Black Yolk in Chicken Eggs – Causes & Facts

Eggs are an excellent and affordable source of protein, which has increased chicken farming. Egg yolks are typically yellow or a shade of orange. So, what do you do when you crack your egg only to find a black yolk inside? Simply put, you can decide whether to eat it if it is a boiled egg.

black yolk chicken eggs

If it is a fresh egg, then the choice becomes simpler, discard it. These two scenarios have different causes. This piece explains these two black yolk phenomena, their reasons, their superstitions, and cases where eating eggs with a black yolk is safe and unsafe.

Causes of Black Yolk in Chicken Eggs

The most common question I get around this issue is, What could have caused my egg to have a black yolk? There are some reasons for this.

– Egg is Rotten

This is one of the most likely causes of a black yolk in your raw egg. Yolks, when fresh and viable, are some shade of yellow or orange. However, as their viability decreases and they begin to rot, this color changes to gray and black.

This results from the exposure of the minerals and the enzymes in the egg to oxygen. An egg with a rotten yolk is also characterized by a pungent odor that is suffocating and nauseating. It is usually compared to the smell of hydrogen sulfide.

– Egg is Contaminated

This factor may cause your raw egg to have a black yolk. If you see black spots or gray spots in the yolk of a fresh egg, then it is contaminated with fungi or bacteria. However, unlike a rotten egg, a contaminated one may not smell as bad. It is good to look carefully at your eggs as you crack them to notice any pigmentation in the yolk and dispose of it accordingly.

Can You Eat Eggs with Black Yolk?

Yes, you can eat an egg with a black yolk. But only under two strict conditions. The first is if the egg has been hard-boiled for longer than intended and the yolk has turned yellow or grey. Smell the egg to ensure it was not rotten before you boiled it. The other scenario is with century eggs. This is a traditional Chinese dish where the egg yolk turns black due to preservation.

Never consume a fresh egg with a black yolk, as this puts you in danger of food poisoning. Some other effects of eating an egg with a black yolk include stomach cramps, stomach pains, headaches, diarrhea, fever, and prolonged vomiting. You can also contract salmonella from eating an egg with a black yolk.

black yolk boiled eggs

Black Egg Yolk in Boiled Chicken Eggs

The yolk may turn grayish or black if an egg is hard-boiled for longer than average. Such an egg is ok to eat but offers little nutritional value. This change in color results from the sulfur in the egg reacting with the iron in the presence of heat and creating iron sulfide.

Iron sulfide is a dark gray compound; hence the yolk color changes after prolonged boiling. To be safe, only consume such a boiled egg if it does not have a foul smell and if there are no darker spots within the back or gray yolk.

Do Chickens Lay Eggs with Black Yolk?

The simple answer is no. No known chicken breed lays eggs with a black yolk. If you encounter an egg with a black yolk, it does not come from the chicken in that state. There was a case in China of a goose that laid black eggs, but scientists attributed this to environmental pollution.

There was not a single case of the same in chickens that that Chinese farmer was keeping. So if you encounter eggs with a black you, they were not laid by your chickens in that state. In some cases, chickens bury their eggs within the bedding, and they are discovered later when changing the bedding. Such eggs have a black yolk as a result of going bad.

Making Black Chicken Eggs – Century Eggs

century eggs

There are several names for century eggs, like millennium eggs or hundred-year eggs. A misconception about their name makes people believe they take a century to complete. Making them takes about a month, and you can do it at home.

The traditional method was to preserve the eggs in a mixture of ash, salt, and lime for several weeks and let chemistry do its thing. Today, you can achieve the same in the comfort of your kitchen using a pickling solution and clay. This is how to go about it.

– Supplies

  • Lye or caustic soda
  • Salt
  • Eggs
  • Plastic wrap
  • Clay
  • A glass jar
  • A scale.

Step 1

Make the pickling solution by mixing one liter of water with 42 grams (1.5 ounces) of lye and 72 grams (2.5 ounces) of salt. Dp this over low heat until the solution has a smooth consistency. Let the solution cool.

Step 2

Put the eggs in the glass jar and add the created solution until all eggs are covered. Label the jar and leave it at room temperature for ten days. Do not disturb the jar during this period.

Step 3

Gently empty the solution and remove the eggs after ten days. Pat them dry with a paper towel. Wrap the eggs with plastic wrap and encase them with clay. Do this gently and with care to avoid breakage. Set this aside at room temperature and leave it undisturbed for three weeks.

Step 4

Remove the clay from the eggs, then the plastic wrap, and gently break open the shells. If the previous steps were successful, your egg whites should be jelly-like, and the yolks should be dark green or black. Serve and enjoy.

Black Egg Yolk Superstition

There are several superstitions surrounding a black yolk in raw eggs. The one commonality among them is that the black yolk is a bad omen.

While eggs are generally considered a symbol of rebirth, the coming of spring, or renewal in some cultures, all of them think of black yolk eggs as a symbol of impending doom, evil and poor crop production.

In fortune telling, eggs are used to foretell a bright or dark future. A black yolk signifies that one’s destiny is dark and marred by calamities.

Many rituals in the East use eggs as a cleansing tool in practices. It is believed that the life within the egg (yolk) absorbs all the negative energy and leaves the person clean. Eggs used in this ritual that reveal a black yolk upon breaking open usually indicate a curse or wrath from one’s ancestors.

Shamans interpret the dream of an egg with a black yolk as an indicator of uncertainty. It is interpreted to mean that a lot is about to unravel in one’s life and that they are ill-prepared for it.


Remember that no breed of chicken will produce eggs with a black yolk. When you crack open your egg and find a color other than yellow or orange, it is always advised to treat the egg as unsafe for consumption. If you encounter a raw egg with a black yolk, discard it immediately.

It is good to properly dispose of such an egg in a sealed container or bag to prevent the pungent smell or the bacteria from spreading in your home or coop. However, if you overestimate the timer and overboil a fresh egg, the black or gray yolk that results from this is safe for consumption.

It is inadvisable to feed such an egg to children, but adults can consume it at their discretion. Eggs are cheap and readily available. Do not risk long-term injury to your health by eating an egg with a black yolk. Always remember that prevention is better than cure.

avatar James
Hey, I'm James, a hardworking homesteader for more than 30 years. I enjoy the feeling of accomplishment that comes from tending my flock. I've raised chickens and ducks for eggs and meat for many years. I also have experience with other poultry too. Learn more

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