Slicing a hard boiled egg at a high angle view
Gray Ring Around Your Hard Boiled Egg? Here's Why
By Nick Johnson
Taking note of the color of your food can be one of the most powerful tools in the kitchen when it comes to determining a quality ingredient. Sometimes boiled eggs can develop an alarming hue while boiling, and it may leave you questioning your breakfast.
Egg whites have many proteins which are connected by sulfur bonds, and when boiled, these bonds break down, which results in hydrogen sulfide production. The hydrogen sulfide is responsible for turning a runny egg into a solid one, but it also interacts with the iron in an egg yolk to release iron sulfide, which causes a gray ring to form between the white and the yolk.
Eating a boiled egg that has a gray ring is perfectly safe, but you can avoid this by beginning the boiling process with cold water and removing the egg shortly after the water has begun to boil. This works to prevent any gray coloring, because iron sulfide is only released around 158 degrees Fahrenheit, so if you can take the egg out before that, you won’t ever have to worry about a gray tint.