The science of stink
EC: Why Overcooked Eggs Smell So Bad
Credit: Gif by PetroglyphFilms via Getty Images, Illustration by Lauren Kolm

Everyone has smelled rotten eggs at some point in their life. The stench has plagued anyone who has made hard-boiled eggs and forgotten about them on the stove for a few extra minutes. Cracking open an overcooked egg will reveal a green ring around the yolk and a wicked stench. Luckily, there are some easy ways to prevent bad egg smell from being a part of your life.

First, let’s look at what causes eggs to smell so bad. Egg yolks have trace amounts of iron, and egg whites have sulfur compounds. Now, with properly cooked eggs, you won’t get a major stink. But as you heat an egg over 140°F, sulfur atoms become free from the albumen proteins and start looking for trouble. That trouble doesn’t start to really get stinky until you heat your eggs past 180°F. Once they're above 180°F, the hydrogen sulfide aroma compounds begin to form rapidly and produce that distinct smell we all know and despise.

Here’s how to prevent it.


The stinky aroma compounds don’t begin to form until the egg is heated over 180°F. So all you have to do is keep your heat a little lower to slow the rate of those compounds from forming. All the proteins in an egg will coagulate at or below 180°F, so it’s key to cook your scrambled or over-easy eggs lower and slower. It’s a little tricky with hard-boiled eggs because you want the white to be firm. A quick fix is to boil the eggs for just a minute or so at the beginning so you set those outer whites and then reduce to a bare simmer for about ten minutes to cook the eggs through.


Eggs can overcook quickly, so time is an important factor. If you’re scrambling or frying an egg, make sure you have your plate ready to go. An extra 30 seconds in a hot pan can give those nasty sulfur atoms the time they need to stink up the joint. Hydrogen sulfides are quite volatile, so if you happen to overcook a bunch of hard-boiled eggs and let them chill overnight, some of their stench will dissipate into the air.


Stinky hydrogen sulfides are produced as the pH of an egg increases. So decreasing the pH will help to stop those aromas from flourishing. This is really only practical when you’re poaching eggs, though. A little bit of vinegar or lemon juice added to the poaching liquid can help prevent them from stinking. Time and temperature are still paramount to not overcooking your eggs though.

Follow these tips will keep your eggs super-tasty and odor free.