The Green Ring: A Harmless Chemical Reaction
That unappealing greenish-gray ring around the yolk of a hard-boiled egg is a common sight, but it’s completely harmless and safe to eat.
It’s a simple case of overcooking. When eggs are heated for too long, the sulfur in the egg white and the iron in the yolk react at the interface between the two, forming ferrous sulfide—the compound that creates the green color.
While it doesn’t affect taste or nutrition, avoiding it is easy with the right technique.
How to Boil the Perfect Egg (Every Time)
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