Have you ever sliced into a hard-boiled egg only to discover a grayish-green ring encircling the yolk? This is a common sight that can cause some confusion about the egg’s freshness or safety. While it might look unappetizing, this ring is a result of a simple, harmless chemical reaction.
The Science Behind the Ring
The distinct color is caused by a compound called ferrous sulfide. The yolk of an egg contains iron, and the egg white (albumen) contains hydrogen sulfide. During the cooking process, these two elements are drawn to each other. When an egg is cooked for an extended period, the intense heat causes these compounds to react at the surface of the yolk, forming the ferrous sulfide that creates the characteristic green ring.
How to Prevent This from Happening
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