Have you ever noticed a grayish-green ring around the yolk of a hard-boiled egg? While it may look unappetizing, it’s harmless and caused by a simple chemical reaction.
The Science Behind It:
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The yolk contains iron; the egg white contains hydrogen sulfide.
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When eggs are overcooked, these compounds react at the yolk’s surface, forming ferrous sulfide, which gives the gray-green color.
How to Prevent It:
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Place eggs in a single layer in a pot and cover with at least 1 inch of cold water.
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Bring water to a full boil.
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Turn off the heat, cover the pot, and let eggs sit for 12–15 minutes.
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Transfer eggs to ice water or run under cold water to stop cooking.
This method cooks eggs fully without forming the green ring and makes peeling easier.
Is It Safe to Eat?
Yes. The green ring is purely cosmetic and does not affect the egg’s safety or nutritional value. Overcooked yolks may be slightly drier and have a sulfur smell, but the egg is still fine to eat.
A helpful visual cue to perfect your hard-boiled eggs next time!
