What you see: A black speck in the white of your hard boiled egg
What it is: A naturally occurring “blood spot” or “meat spot” that turned black after exposure to heat
Eat or toss: Eat!
“Blood spots” in raw eggs can lead to black spots in boiled eggs
Sometimes a chicken’s egg-making machinery misfires and a bit of blood or a clump of brown protein winds up inside the egg. These stray bits, known as blood spots or meat spots, can certainly be off putting. But as long as you cook the egg, there are no associated food safety issues.
In my experience, blood and meat spots visible when I first crack open an egg usually disappear or at least go unnoticed once an egg is scrambled. But in this hard boiled egg, cooking seems to have transformed a blood spot from a little bit gory to a little bit ominous.
Why did the egg’s blood spot turn black?
Deana R. Jones, who studies eggs at the USDA’s National Poultry Research Center, said that blackening could be due to the heat of cooking and reactions between the blood or protein in the spot and minerals in the egg.
Jones observed that since the spot was very close to the surface of the egg it would have been exposed to more heat than the yolk and parts of the white that were closer to the egg’s center.
“It’s literally a quality issue not a food safety issue,” she said of the spot.
In terms of food safety, Jones did note that the egg in the image above is not truly hard cooked. That extra moisture you see in the center of the yolk means that heat didn’t penetrate quite enough to guarantee that all potential pathogens were killed.
For healthy adults, this is a still pretty low risk egg. But while Jones said wouldn’t haven’t any concerns about the black spot, she would think twice before serving a not-quite-fully cooked egg like this to a vulnerable person, like a young child or immunocompromised person.
“Cooked” blood or meat spots can show up in different ways
The hard boiled egg featured at the top of this post had a cooked “spot” embedded in the yolk. But the egg below also appears to have evidence of cooked blood or meat spots. In that case they look almost like bits of pepper on the yolk or the white just around the yolk. Still, no food safety concerns with the speckles, just a quirky looking egg.
- Deana R. Jones. Research Food Technologist. Egg Safety and Quality Research Unit. U.S. National Poultry Research Center. USDA Agricultural Research Service.
- Is that blood in my egg? EatOrToss. April 2017.
- What’s up with brownish specks in eggs? EatOrToss. July 2017.