…they were cooked too long or the water they were cooked in had a very high iron content.

Don’t worry, although it may not look particularly appetizing, it’s completely harmless. You can eat your eggs without any worries!

Why does this happen?

It’s a simple chemical reaction:

When heated, sulfur is released in the egg white (as hydrogen sulfide gas).

This gas migrates into the yolk, which contains iron.

There, sulfur and iron react to form iron sulfide.

This compound is gray-green in color and is deposited exactly at the border between the egg white and the yolk.

How can you avoid the green ring?

Don’t overcook: A large egg is perfectly hard-boiled after about 8 to 10 minutes in boiling water. Anything longer than 11–12 minutes will cause the color to change.

Shocking: Immediately after boiling, plunge the eggs into ice water. This will stop the cooking process abruptly and prevent further reaction of the gas with the iron in the yolk.

Fun fact: The consistency of the yolk often becomes a bit “sandy” or dry when cooked this way. But with a pinch of salt and maybe a little remoulade, it still tastes great!

Have you ever had an egg for breakfast or made it into an egg salad?