Why does a green ring appear around hard-boiled eggs?

Why Does a Green Ring Appear Around Hard-Boiled Eggs?

Hard-boiled eggs are a simple, nutritious snack and a staple ingredient in many recipes. But if you’ve ever peeled a hard-boiled egg only to find a gray-green ring around the yolk, you might have wondered — what causes this discoloration, and is it safe to eat?

What Causes the Green Ring?

The green or grayish ring that sometimes forms around the yolk of a hard-boiled egg is caused by a chemical reaction between sulfur and iron. Here’s how it happens:

When eggs are boiled, the heat causes the iron in the yolk and the sulfur in the egg white to react.

This reaction produces iron sulfide, which has that distinctive greenish-gray color.

The ring usually forms when eggs are overcooked or cooked at too high a temperature, which encourages this reaction.

Is It Safe to Eat?

Absolutely! The green ring is harmless and does not affect the safety or nutritional value of the egg. It’s simply an aesthetic change caused by chemistry.

How to Prevent the Green Ring from Forming

If you prefer your hard-boiled eggs without the green ring, try these tips:

Don’t overcook: Boil eggs just long enough — about 9-12 minutes depending on size.