why do some eggs need to be refrigerated and some don’t?

Question

I’ve been curious after seeing non-refrigerated eggs in Japan

In: 2

Answer 1

Eggshells are porous, meaning they have a lot of little holes in them. To seal those little holes a chicken’s body creates a coating we call bloom. In the US eggs are washed to make them look cleaner and more appealing. This washing also removes the bloom with means all those little pores in the egg shell are now open and bacteria can get inside them. So washed eggs need to be refrigerated to keep any bacteria that gets inside from growing too quickly as the coldness of the fridge inhibits bacteria growth. If, however, the bloom is left on eggs then refrigeration is unnecessary because bacteria can’t get inside the egg to grow.