So, what's up with that icky discoloration? It turns out that
Those funky, discolored rings in your hard-boiled eggs may make you wonder if they are harmful to eat. Fortunately, the United States Department of Agriculture (USDA) website clearly states the green or gray color in the eggs is “safe to consume.” So, if you happen to see a little ring around your egg, don't worry!
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.
The white of the egg will also turn a tan color as the glucose in the egg undergoes a Maillard reaction, the same process that makes cooked meat and caramelized onion turn brown. Most hard-boiled egg recipes call for heating the egg for a matter of minutes, or, in the case of slow-cooked eggs, a few hours.
How Can You Tell If Hard-Boiled Eggs Are Bad? The best way to test if your eggs are still good after you've boiled them is, again, the smell test. Basically, you'll notice the smell is off if an egg is starting to go bad. This is true for raw eggs and it's true for boiled eggs—the funk doesn't lie.
Hard-cooked eggs can also have black or brown spots on the albumen (egg white) from overcooking or burning. Discoloration due to overcooking does not impact food safety and these eggs are safe to eat.
The American Egg Board suggests that you cook eggs in hot, not boiling, water, and then cool immediately to minimize the green ring.
“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.
They should discard eggs with any unusual discoloration inside, such as a pink, iridescent, or greenish egg white or yolk. However, eggs that develop a green ring on the hard-cooked yolk after cooking are safe to eat, according to the USDA.
In many cases, it's simply a matter of changing the cooking time or temperature. Rapidly cooling hard-boiled eggs can help to minimize the green appearance on the yolks. Whether your egg yolks are a rich golden hue or slightly yellow in appearance, the color of the yolk shouldn't be a huge concern.
If the egg white is pink or iridescent this is an indication of spoilage due to Pseudomonas bacteria. Some of these bacteria can make us sick when eaten and they will produce a greenish, fluorescent, water-soluble color. Also, a spoiled egg (cooked or raw) will have an unpleasant odor once you crack it open.
Hard-boiled eggs, peeled or unpeeled, are safe to eat up to seven days or one full week after they were cooked. To make sure they stay fresh, allow the cooked eggs cool a bit, and then store them in a sealed container in the refrigerator.
Gray eggs are the result of a chemical reaction
It's easy to assume that if your scrambled eggs are gray, it's because they've gone bad, but the truth is the color has nothing to do with the taste. They might look unappetizing, but gray eggs are perfectly safe to eat.
Adding white vinegar or apple cider vinegar to your pot of water allegedly results in softer, easier-to-peel eggshells. That's because the acid in vinegar dissolves some of the calcium carbonate that makes up the egg's hard exterior.
Off-color egg white, green or iridescent – Spoilage due to Pseudomonas bacteria, a very common type of bacteria that healthy people often carry without knowing it. This bacteria produces a greenish, fluorescent, water-soluble pigment in the egg white. If you come across an egg with an off-color egg white, discard it.
Cloudiness of raw white is due to the natural presence of carbon dioxide that has not had time to escape through the shell and is an indication of a very fresh egg. As an egg ages, the carbon dioxide escapes and the egg white becomes more transparent.
Using the wrong pot.
Not only will the eggs cook unevenly, but there's more risk of an egg cracking. Follow this tip: Use an appropriately sized pot for the number of eggs you're cooking.
Some people prefer to peel their hard-boiled eggs before storing – and that's A-OK. You'll just need to take a few extra steps: Transfer hard-boiled eggs to a bowl of cold water immediately after cooking to help them cool down faster. Peel the eggs under running water.
Bring the water to a boil over medium heat and as soon as the water reaches a boil, cover the pot and set a timer for 10 to 12 minutes. Once the eggs are fully cooked, carefully transfer them to an ice bath to instantly stop the cooking process.
Hard-boiled eggs have firm yolks and whites. Avoid cooking them for too long otherwise the protein in the white toughens and becomes rubbery.