Did you know that not everyone washes and refrigerates their eggs? It’s true! The way eggs are stored depends on where they’re produced.

Prompted by concerns about spoilage and foodborne illnesses, U.S. egg producers and processors began washing and refrigerating their eggs in the early 1970s. Other countries soon followed suit, and eggs are now washed and refrigerated in Canada, Japan and Scandinavia.

But in most of Europe, eggs are neither washed nor refrigerated. They are kept at room temperature, even in stores. This is possible because a chicken’s egg is coated with a thin, protective “cuticle,” or membrane, that may prevent Salmonella and other bacteria from penetrating the shell — making refrigeration less necessary. Washing the egg washes away the cuticle.

“The long-held belief in Europe has been that you don’t want to disturb the cuticle of the egg after it comes out of the reproductive tract because it’s protective,” says Deana Jones, an Agricultural Research Service (ARS) food technologist in Athens, Georgia.

In a study, Jones compared the quality of eggs stored using the European and U.S. approaches, along with two other common storage techniques. The results, published in Poultry Science, show that the U.S. approach is the most effective, ensuring the highest quality eggs after 15 weeks of storage.

The results were not surprising, since refrigeration helps to keep so many foods fresh, Jones says. Also, research has shown that the cuticle degrades after the egg is laid, so it’s not as protective as some may think.

“Basically, the key is that egg quality stays high with refrigeration and degrades rapidly without it,” Jones says.

The study can be found here.