The Difference Between Washed And Unwashed Eggs Is More Than You Realize

When you buy eggs from the grocery store in the United States, by law they are "washed" eggs, which you would assume makes them safer and less likely to cause disease. While the washing process does protect against one of the most serious egg-related illnesses, salmonella, it also makes the eggs more susceptible to spoilage further down the line.

Washing eggs here in the States requires them to be cleaned with water that is at least 90 degrees Fahrenheit, an odorless detergent, and finally a sanitizing solution to ensure no bacteria remain. While this process does a great job of removing the threat from dirt and bacteria on the egg shell, it also removes an important part of the shell — the bloom. The bloom is a natural coating on the egg which "seals" the pores on the exterior and helps to keep bacteria out. The process of industrially washing eggs removes the bloom, and with it, the natural protection the egg had from the outside world.

The bloom seals the thousands of pores on the egg, which need to be open for gas exchange before the egg is laid. The bloom is then added at the final stage before laying, to protect the egg (particularly the yolk) from any nasty microbes that may be picked up during the laying process.

If you've ever been egg shopping outside the U.S., you may have been surprised to see eggs being sold on shelves, rather than in refrigerators. In many countries, including in the European Union, the laws regarding egg safety are very different from ours, and change the way in which eggs need to be stored. Unwashed eggs still have the protective bloom in place, meaning they can be stored at room temperature for weeks without risk of spoilage. Many customers still choose to refrigerate their eggs however, as it allows them to last even longer than the specified "best by" date.

The difference in refrigeration requirements reflects the contrasting strategies adopted by the countries to keep consumers safe when eating eggs. Industrial washing ensures that feces and other sources of bacteria are removed from the egg shells before they make it to the grocery store, but makes them susceptible to bacteria in the long term. Leaving them out at room temperature would create the perfect conditions for bacteria to grow.

Unwashed eggs, on the other hand, rely on the hygiene standards of the farms and producers to prevent contaminated eggs from reaching the shelves, but the natural protection of the bloom means that the eggs last longer at room temperature without spoiling. If you would prefer to buy unwashed eggs in the U.S., some states allow them to be sold at farmer's markets or direct from the farm. Otherwise, all U.S. eggs are washed, meaning you must keep them in the fridge to ensure they are safe to eat.