A green or gray ring around the yolk of a hard-boiled egg may look unusual, but it usually does not mean the egg has spoiled. In most cases, this discoloration is harmless and results from a natural chemical reaction that occurs during cooking.
The ring forms when sulfur compounds released from the egg white react with iron naturally present in the yolk. This reaction produces iron sulfide, creating the familiar greenish or grayish color around the yolk.
A green or gray ring around the yolk of a hard-boiled egg may look unusual, but it usually does not mean the egg has spoiled. In most cases, this discoloration is harmless and results from a natural chemical reaction that occurs during cooking.
The ring forms when sulfur compounds released from the egg white react with iron naturally present in the yolk. This reaction produces iron sulfide, creating the familiar greenish or grayish color around the yolk.
