What's Up with that Gray Ring Around My Hard Boiled Egg Yolk?

Let's talk about hard boiled eggs for a minute.

Hard boiled egg pros:

1. They're an excellent source of protein that will actually keep me full all morning.
2. They're a great make-ahead option to guarantee I have breakfast on lock all week--and they even come in their own protective travel case (i.e. the shell)!
3. They're the perfect topping for an Instagram-worthy toast with all that golden yolk glory.

1. Some of my colleagues would argue they're not exactly the most "office-friendly" breakfast selection in terms of aroma.
2. Sometimes I lose half of my breakfast when attempting to separate it from the protective travel case.
3. And sometimes... the whole Instagram-worthy golden yolk glory doesn't happen. And I end up with a dull yellow yolk surrounded by a questionable ring of greenish gray. It's incredibly disappointing.

Ew. It fell so short of the perfect egg yolk porn I was hoping for. So, what's up with that icky discoloration?

It turns out that hard boiled eggs can take on that greenish gray color around the outside of the yolk because of a chemical reaction between the iron in the yolk and sulfur, which is present in the white. The reaction occurs when the egg is exposed to temperatures that are too high, or if the egg is exposed to high heat for too long. Basically, I overcooked them. Awesome.

That said, besides being a bit on the rubbery side, an over-boiled hard boiled egg is still fine to eat. Despite the less-than-appetizing color that results, the reaction between iron and sulfur that occurs when you boil your eggs for too long does not make them unsafe for consumption. To avoid the dreaded gray ring in the future, I would suggest following one simple, yet foolproof, technique: Set a timer.

In order to get the just-firm, perfectly golden yolks of my hard boiled dreams, this is the method I've found to be most reliable:

1. Bring a pot of water to a boil first (yes, before your eggs go in).
2. Gently place the eggs into the pot of boiling water using a slotted spoon.
3. Cover the pot and turn off the heat.
4. Let stand for 8 minutes (set a timer!).
5. Using the slotted spoon, remove your eggs and immediately plunge them into an ice bath until cool (I've also found that my egg shells generally slip off easily using this method).
6. Remove shells and enjoy glorious hard boiled eggs.