|Photo from American Egg Board|
Q. I was wondering what I am doing wrong. Almost every time I make hard boiled eggs, I get this greenish color covering the yellow yolk. Do you know what causes that? Is it harmful? C.D. Grandville, MI
A. According to the American Egg Board’s “Eggcyclopedia”, you probably cooked your eggs either too long or at too high of a temperature. The greenish-grey ring between the yellow and white of a hard cooked egg results from a reaction between the sulfur in the egg white and the iron in the yolk.
Is the green ring harmful? No, but it does not look very appetizing.
A sure-fire method of cooking hard-cooked eggs, which will avoid the dreaded green ring, is to place the eggs in a saucepan in a single layer. Add cold water to cover the eggs by one inch. Heat on high just to boiling, then remove from the burner and cover the pan. Let the eggs stand in hot water for 12 minutes for large eggs (15 minutes for extra-large, 9 minutes for medium). Drain immediately and serve warm. Or cool under cold running water then refrigerate.
The Eggcyclopedia has lots of info, from egg safety, to recipes, to trivia. I don’t make hard-cooked eggs very often, maybe twice a year, and one thing that I forget is to buy my eggs ahead of time. The Egg Board recommends to buy your eggs for hard cooking and peeling (used for deviled eggs, as an example) at least 7 to 10 days ahead of when you need them. This allows the eggs to develop an air pocket on the larger end, making it easier to peel after cooking and cooling.