Why…. Do Eggs Float?

A few of us have been in the situation of coming back from a trip and having no food, but still desperate to salvage something from the fridge and thinking “I’m sure these eggs are still fine to eat”.. But after cracking open what looks like a perfectly normal egg into your pan, your nose is invaded with a cloud of sulphur. From that point, there’s no doubt that you will not be having eggs this morning, even if your appetite somehow endured through the rotten egg stench.

Assuming you are like most people and don’t have “rotten egg” as one of your top favorite smells. One way to avoid this situation from occurring is to place possibly questionable eggs into a clear glass of water and see how well they float.

Egg laying on the bottom = Fresh and good to eat.

Egg that completely floats in the water = Has gone bad and is not worth cracking and risking the sulphur smell.

Why Do Eggs Float?

The reason eggs begin to float when they become older is due to an air pocket inside the shell- which is meant to be an air source for chicks during growth. The air pocket along with thousands of tiny pores on the egg allow the chick to get oxygen, and for carbon dioxide to leave the egg. ****

*******Egg pores also lets food dye into the shell so you can have colorful Easter Eggs!!*******

All eggs, (fertilized and unfertilized) have this air pocket. The longer the egg is around, the more air that enters the eggs air pocket. The more air in the egg, the more the egg will float. This also means that an older egg has had more opportunity for bacteria to enter the egg through the pores, beginning to decay the egg and cause the sulphur smell. So an old egg will float because of the increased size of the air pocket, and it will have a sulphur smell because of bacteria contamination.

A reason you find grocery store eggs in a refegeriated section is to slow this contamination process. However, if you had fertilized eggs, a few weeks is not enough time to have a chick grow and hatch….but a few week old eggs would be bad and be filled with bacteria…

So

Why Do We Refrigerate Eggs?

The reason unfertilized grocery eggs found in the refrigerated section would go bad before a fertilized egg would is because of a protective coating on the egg called a cuticle.

The cuticle is thin protective membrane on the outside of the egg that is meant to slow things getting into and out of the egg. If an egg is fertilized, this cuticle keeps the chick safe from bacteria, but still allows the chick to breathe. However, this cutice can be easily removed in the cleaning process…which all of grocery store eggs go through. Removing the cuticle membrane removes the eggs protection from bacteria and allows the egg to go bad at a quicker rate.