Did you know that eggs are naturally germ-free, due to bacteria-fighting proteins found within the egg white? Bacteria may invade the egg through a crack in the shell, and maybe even make it past the membrane, but when it hits the egg white, three proteins work together to provide effective protection against contamination. The catch? That egg has to come from a healthy chicken. An Aug. 31 National Public Radio (NPR) segment by Anna Vigran presented this interesting look inside the shell:
“One of these [proteins] is called lysozyme. It isn’t just in egg whites — it’s also in tears, saliva and the drippy stuff that comes out of your nose. In fact, that's how it was discovered by Alexander Fleming (who also discovered penicillin) — Fleming happened to notice that when drips from his nose fell onto certain bacteria, they died.”
According to the NPR report, Lysozyme in effect explodes illness-causing bacteria. The other two proteins prevent bacteria from obtaining what they need to grow.
So why are so many people battling the recent salmonella outbreak? Those proteins are no match for the level of contamination that sickened hens at the two Iowa facilities from which millions of tainted eggs were shipped. In the segment, retired microbiologist John Ingraham, author of March of the Microbes (Harvard University Press), says that salmonella-infected hens are likely to lay salmonella-infected eggs:
“Ingraham says if the egg comes from healthy chickens, like his, there’s no problem. But as the current egg recall shows, chickens are notoriously susceptible to infection with salmonella. And if the chicken that's laying the egg is infected with salmonella, it’s likely its eggs will be infected, too. That’s why we’re told to cook eggs and keep them cold — cooking kills the bacteria and cool temperatures slows microbial growth and helps the eggs last longer.”
Ready to enjoy eggs from your own backyard? Visit our Chicken and Egg Page, where you’ll find everything you need to know to get started.