What makes hard boiled egg yolks turn grey around the edge. And while we are all here, is it grey, or gray?
I occasionally eat a hard boiled egg as a quick “to go” snack or on a salad. It is really the only time I eat eggs so I boil up a dozen and keep them in the refrigerator for a couple of weeks until they are gone. I notice that some of them, I figure the older ones, turn grey around the edges of the yolk. They must not be rotten, because I eat them and nothing bad happens. But why does that happen. Why do they turn grey? Or do they turn gray?
This question is in the General Section. Responses must be helpful and on-topic.