When I popped open a carton of eggs to make breakfast this morning, I saw that a few of them had wrinkled shells.
I hadn’t seen eggs like these before, and I wasn’t sure if they were safe to eat. So I did what I usually do in cases like these: I went online and did some research.
If you too got wrinkly eggs, no matter if you bought them from the grocery store or you keep chickens in your backyard, you’ve come to the right place. Before you rush to cook them or throw them away, let me share everything I found out (and the things you need to know).
Infectious bronchitis virus, an acute and contagious respiratory disease in hens, can cause them to lay eggs with wrinkled shells. This can sometimes happen years after the hens are infected, as they carry the disease for life.
Chicks infected with bronchitis cough often. When they do, their muscles contract and squeeze the egg’s shell while it’s still forming, which causes it to come out wrinkled.
So how safe to eat are wrinkled eggs, exactly?
Here’s what the general consensus among food scientists and poultry experts says.
Wrinkled eggs—typically a sign of infectious bronchitis—are definitely a problem for farmers. This contagious disease can shorten their chicks’ life expectancy and result in higher flock morbidity as a whole. But if you’re a consumer, the good news is that there’s nothing for you to worry about.
Eggs with wrinkled shells are generally safe to eat. However, if the egg has a cracked or broken shell, it is unsafe and should be discarded immediately (as harmful bacteria can enter from the outside).
There are three reasons why wrinkled eggs are okay.
First and foremost, according to The Pennsylvania State University, the virus is not transmitted through the egg (please note that the link is not for the faint-hearted; it contains graphic images of infected chickens).
Second, according to the Portuguese Poultry Science Association (APCA), the aerial virus that causes infectious bronchitis in poultry belongs to a group of viruses that do not infect humans. As explained by Mayo Clinic, bronchitis in humans is caused by the common cold or a completely different set of viruses.
Last but not least, infectious bronchitis, like the rest of the viruses that belong to its group, is highly susceptible to fluctuations in environmental temperature (Guzmán, Hidalgo).
Just like its peers, it usually is inactivated at temperatures of 132.8 to 149°F, which is well below the heat of your stove or oven when making eggs (OIE Terrestrial Manual 2018).
But there’s another, less concerning reason why the hen could have laid wrinkled eggs, writes chicken keeper, and master gardener, and coop-to-kitchen cook Lisa Steele in her blog, Fresh Eggs Daily.
“If the hen is startled while laying,” Steele says, “such as by a dog barking, predator lurking, thunderstorm or other abnormal stressor, the shell can end up with a ridge in the surface.”
When you come to think of it, that’s normal and kind of expected. If you were a hen, you probably wouldn’t want dogs barking, foxes lurking, and thunder striking anywhere near you either!
Should You Wash Your Hands After Handling Raw Eggs?
Eggs are a staple in every kitchen. But, as it turns out, not every home cook knows how to handle them properly. A 2013 survey found that only 48% of Americans wash their hands after cracking eggs.
Now, this is a problem. One of the top causes of food-borne illness in professional and home kitchens is cross-contamination—or when you unwillingly transfer bacteria from the surface of one food to another, usually with your hands, cutlery, utensils, or cutting board.
According to the USDA, “proper refrigeration, cooking, and handling should prevent most egg-safety problems.” The agency recommends washing your hands before and after handling raw eggs, as well as any equipment or work surfaces that came into contact with them.
Should You Wash Eggs Before Cracking Them?
Some cooks will advise you to wash eggs before cracking them. But many say precisely the opposite—and for a good reason!
Don’t wash raw eggs before cracking them; it can do more harm than good. You can actually increase the risk of contamination by doing so because the water can be sucked into the egg through the shell’s pores.
The USDA requires eggs to be washed with a sanitizing rinse at the processing plant, as bacteria can end up on the shell’s surface from the hen’s reproductive tract. So there’s no need for you to do it at home.
Yes, wrinkled eggs are safe to eat. Wrinkled shells can be a sign that the hen was stressed or that it was infected with avian bronchitis. While this results in the hen laying eggs that are less appealing to the eye, they’re just as safe to eat as their perfectly oval counterparts.
As a general rule of thumb, always remember to wash your hands before and after handling raw eggs. This helps you keep the risk of cross-contamination to a minimum, which is the primary cause of most food-borne illnesses.