By Hannah Haas Burkhalter and Hannah Haas Burkhalter Updated October 17, 2016
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Let's talk about hard boiled eggs for a minute.
Hard boiled egg pros:
- They're an excellent source of protein that will actually keep me full all morning.
- 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)!
- They're the perfect topping for an Instagram-worthy toast with all that golden yolk glory.
- Some of my colleagues would argue they're not exactly the most "office-friendly" breakfast selection in terms of aroma.
- Sometimes I lose half of my breakfast when attempting to separate it from the protective travel case.
- 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 p*rn 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:
- Bring a pot of water to a boil first (yes, before your eggs go in).
- Gently place the eggs into the pot of boiling water using a slotted spoon.
- Cover the pot and turn off the heat.
- Let stand for 8 minutes (set a timer!).
- 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).
- Remove shells and enjoy glorious hard boiled eggs.
By Hannah Haas Burkhalter and Hannah Haas Burkhalter
FAQs
That iron sulphide is what creates the odd color around the yolk. So, if you see these little rings in your hard-boiled eggs, it simply means the eggs may be slightly overcooked.
Is it safe to eat a boiled egg with a GREY ring around the yolk? ›
The dreaded grey ring on boiled eggs, explained
Although it may look unappealing, the USDA assures us that the green colour is safe to consume!
Why is there a GREY ring around my hard-boiled egg? ›
A greenish-gray ring may appear around a hard-cooked egg yolk. It's unattractive, but not harmful. The ring is caused by a chemical reaction involving sulfur (from the egg white) and iron (from the egg yolk), which naturally react to form ferrous sulfide at the surface of the yolk.
What causes the GREY green ring around the yolk in boiled eggs? ›
A: The green ring around the yolk of a hard cooked egg happens because hydrogen in the egg white combines with sulfur in the yolk. The cause is most often related to boiling the eggs too hard for too long.
Is it normal for boiled egg yolk to be GREY? ›
This process happens at 77°C for ovalbumin. But above 70°C, the sulphur also forms hydrogen sulphide that reacts with iron in the egg yolk to form iron sulphide, and this gives it a greenish grey colour. You can prevent this by running the eggs under the cold tap to lower their temperature as soon as they are cooked.
How to boil eggs without a grey ring? ›
The American Egg Board suggests that you cook eggs in hot, not boiling, water, and then cool immediately to minimize the green ring.
How to tell if a hard-boiled egg is bad? ›
“If the egg is discolored or has a greenish ring around the yolk, it's likely gone bad.” A bad hard-boiled egg may also have a sulfuric smell, adds Marcus. The bottom line on hard-boiled eggs: “If the egg is slimy, mushy or smells bad, toss it,” says Steele.
What happens when you overcook hard-boiled eggs? ›
Overcooking can result in a rubbery texture and a dry taste. Some people may find this unappetizing and choose not to eat them. Nonetheless, overcooked hard boiled eggs are safe to eat as long as they have been properly stored and are not past their expiration date.
How long do boiled eggs last in the fridge? ›
A quick beginner's tip is that hard-boiled eggs can be preserved up to 7 days in the refrigerator. If you are thinking about using your hard-boiled eggs in a recipe, the trick is to use old eggs. When they get older, they tend to lose moisture through their shell.
How long do you hard boil an egg for? ›
Hard boiled eggs should be cooked for about 10-12 minutes. This timing avoids a powdery, dry yolk that comes from overcooking while keeping it solid enough for applications like devilled eggs or egg salad.
“When an egg is cooked for too long and/or at too high a temperature, the sulfur in the egg white combines with the iron in the yolk and creates ferrous sulfide, which has a green tint,” she explains. Unfortunately, this chemical reaction—which scientists call denaturation—isn't limited to hard-boiled eggs.
Why do egg yolks develop a GREY ring when cooked? ›
That iron sulphide is what creates the odd color around the yolk. So, if you see these little rings in your hard-boiled eggs, it simply means the eggs may be slightly overcooked.
Why is there a black ring around the yolk of a boiled egg? ›
That iron sulphide is what creates the odd color around the yolk. So, if you see these little rings in your hard-boiled eggs, it simply means the eggs may be slightly overcooked.
Is it safe to eat hard-boiled eggs with grey yolk? ›
When eggs are boiled for long, the yolk becomes paler in color and eventually turns a greenish-gray. This color occurs when you overcook the egg, as this makes the iron from the yolk react with the hydrogen sulfide from the white ( 9 ). While this might affect the texture and mouthfeel, it's safe to eat.
What is the GREY ring around the hard boiled egg? ›
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.
What happens if you boil an egg for too long? ›
The longer you cook the egg, the more likely you are to end up with a rubbery white and a green yolk. Why does the yolk turn green? The green-gray color (and the whiff of sulfur smell that often accompanies it) comes from the reaction of iron in the egg yolk and sulfur in the egg white.
What color indicates a spoiled egg? ›
If your egg white has a green or iridescent look, it may have harmful bacteria. It may not be safe for consumption. If you notice that the color is off, smell your egg. It's always good to err on the side of caution and throw out eggs that may be bad.
What are the GREY marks on eggs? ›
Eggs in General
These grayish lines are referred to as "cage marks," not cracks. Sometimes when eggs are freshly laid, contact with the cage wire will draw moisture toward that part of the shell. The moisture is retained in that part of the shell and results in a grayish appearance.
Can you tell if an egg is bad by the color of the yolk? ›
The most accurate way of testing whether your eggs have gone bad is to crack them open. If the yolk or white has any discoloration, the egg is no good. Discoloration is an indication of bacterial growth. If your eggs look good but have an off or sulfuric smell to them, they are bad.
Is it safe to eat an egg with a dark spot on the yolk? ›
Absolutely – eating an egg that has a blood spot won't hurt you. While you may wish to remove the spot with the tip of a knife and dispose of it, there is nothing in it that's harmful for human consumption.
