When I was little, my parents hid my Easter basket before they went to bed so I could hunt for it Easter morning. The basket always contained at least one hard-boiled egg. Now we’re told we shouldn’t leave hard-boiled eggs out overnight. There was never a problem before. Why the change?
First, let’s be clear: It’s never been a good idea to keep any perishable food out at room temperature for more than two hours. You can count yourself lucky that you never got sick eating those eggs.
Or, it’s possible you did get sick and never associated the illness with Easter eggs. Some types of foodborne illness take days to develop. You might have mistakenly associated an illness with something you had eaten more recently, or even to a flu bug.
In any case, please set your skepticism aside and pay attention to the experts. Why? Foodborne pathogens thrive in protein-rich foods (like eggs) and can multiply rapidly between 40 degrees and 140 degrees Fahrenheit. Just a few cells can proliferate enough to cause illness.
It’s true that when eggs are properly cooked, any bacteria on the shell or lurking inside the egg are killed. But boiling the egg also removes a natural protective coating on the outside of the shell provided by the hen when she lays the egg. When that coating is lost, the shell is more porous, and it’s easier for bacteria to enter the egg simply through regular handling.
The U.S. Department of Agriculture’s Food Safety and Inspection Service has a detailed FAQ about egg safety available at http://bit.ly/FSISeggs. It includes information such as:
- Hard-boiled eggs spoil faster than raw eggs because of the loss of the outer protective coating during cooking. They should be consumed within a week, while properly refrigerated raw eggs are good for three to five weeks.
- Fresher eggs are harder to peel when hard-cooked than older eggs. The reason is that an air cell in the large end of the egg between the shell and the membrane grows larger the longer the raw egg is stored. Older eggs float in water because the air cell is bigger.
- Don’t worry if a green ring forms on a hard-cooked yolk. It’s caused by sulfur and iron compounds in the egg reacting on the yolk’s surface, often because of overcooking. It could also be caused by high iron in the cooking water. It’s perfectly safe to consume.
Chow Line is a service of Ohio State University Extension and the Ohio Agricultural Research and Development Center. Send questions to Chow Line, c/o Martha Filipic, 2021 Coffey Road, Columbus, OH, 43210-1044, or firstname.lastname@example.org.
Editor: This column was reviewed by Linnette Goard, field specialist in food safety and management for Ohio State University Extension.
For a PDF of this column, click here.
OSU Extension, Food Safety and Management