The biggest health risk associated with eggs is being exposed to Salmonella bacteria. Most types of Salmonella grow in the intestinal tracts of animals and are passed through their feces. Most humans become infected with Salmonella after eating foods that are directly or indirectly contaminated with animal feces. With chicken eggs, the eggshell is exposed to Salmonella usually after the egg has been laid as a result of poor animal management practices (i.e. the bird is living in a feces infested condition) and not necessarily from backyard chickens.
If eggs can get dirty after being laid, it logically makes sense to wash them, right? Washing fresh eggs will help eliminate the risk of contamination, right? Wrong.
Eggshells are almost entirely composed of tiny calcium carbonate crystals. Though an eggshell appears solid to the naked eye, it has as many as 8,000 microscopic pores between the crystals forming the shell. These tiny pores allow for the transfer of moisture, gases, and bacteria (e.g. Salmonella) between the inner and outer eggshell.
Nature has provided an efficient and effective defense against contamination through the pores in an eggshell. Just prior to laying an egg, a hen’s body deposits a protein-like mucous coating on the outside of an egg. This protective coating is called the “bloom” or “cuticle.” This protective coating seals the pores of the eggshell, thereby prohibiting the transfer of bacteria from the exterior to the interior of the egg.
Here’s the rub. An egg’s bloom remains intact so long as the egg is not washed. No matter if you think you know how to wash fresh eggs, just the act of rinsing or washing an egg removes this protective layer and re-opens the eggshell’s pores.
Interestingly, the United States is one of the only countries in the world that requires the washing of commercially produced eggs, and has spent vast resources in developing methods for how to wash fresh eggs. The vast majority of our European counterparts legally restrict commercially produced eggs from being washed. In Ireland, for example, only unwashed eggs can achieve Grade A or AA. Washed eggs, under Ireland’s Food Safety regulations, receive a B grading and cannot be sold at retail.
Also noteworthy is the fact that an egg with its bloom left on does not need to be refrigerated. This is the reason that most Europeans do not keep their eggs in the fridge but rather on the counter.
How to Wash Chicken Eggs
Even if you feel the need to know how to wash fresh eggs, not washing your eggshells is the simplest and most natural approach to protecting the integrity of your eggs preventing the spread of Salmonella. However, perhaps not washing an egg that has dropped out of the rear end of your beloved bird simply grosses you out. You understand the “no wash” argument, but still you feel an overwhelming need to clean your eggs regardless of logic.
If you are in the “wash-your-eggs” camp, then it is important to discern the best method to do so. One should never use bleach, soap or other chemical cleaners to wash eggs. When the bloom is removed from the eggshell, these unnatural substances can then pass through the shell’s pores and contaminate the interior of the egg which is consumed. Moreover, some chemicals found in detergents and sanitizers may actually increase the porosity of the shell making it even more susceptible to bacteria.
Washing eggs in cold water is also ill-advised. Washing with cool or cold water creates a vacuum effect pulling unwanted bacteria inside the egg even faster. Similarly, soaking dirty eggs in water is unsafe. An egg’s bloom is quickly removed by contact with water, leaving the shell’s pores wide open to absorb the contaminants in the water in which the egg is soaking. The longer an egg is left soaking in water, the more opportunity for Salmonella and other microbial contaminants to penetrate the shell.
The best method for how to wash fresh eggs is by using warm water that is at least 90 degrees Fahrenheit.Washing with warm water causes the egg’s contents to expand and push dirt and contaminants away from the shell’s pores. Never soak eggs, even in warm water. It is unnecessary and encourages the transfer of contaminants to the inside of the eggs. Moreover, washed eggs must be immediately and thoroughly dried before being stored. Putting eggs away wet also encourages the growth and transfer of bacteria on the eggshells to the egg’s interior.