Food experts and cooks have always taught people the simple way of checking eggs if they are fresh or not. Â By simply putting them in water, a person can easily spot the fresh eggs from the bad ones. Â Fresher eggs are the ones that sink and stay at the bottom while the bad ones float in the water. Â The reason for this is also simple. Â Bad eggs float in water because of the increased air content inside the shells. Â With more air inside the shells, the eggs will become more buoyant and float in the water. Â Eggs that stay in the fridge for several weeks, for example, will have more air in the shells when compared to fresh eggs. Â Because of the longer time spent in the fridge, the eggs will turn bad and float in water.
Eggshells are considered porous enough to allow air molecules to pass through them. Â It is even said that a single egg can actually have thousands of pores in its shell. Â Some chefs and cooks even take advantage of the porous shells by sealing the eggs in a container with a flavoring agent. Â Over a certain period of time, the eggs will develop some of the taste of the flavoring agent. Â If eggs are left uncooked for several days or weeks, there is also a greater tendency for air pockets to build up inside the shells. Â The more air pockets there are, the more buoyant the eggs will become. Â The air inside the egg shells will also result in the decay of the eggs which is why people always consider the eggs that float in water as rotten eggs.
Some people also point out that the air pockets that build up inside the eggshells are caused by bacteria. Â The more bacteria a particular egg contains, the faster will be the air pocket build-up which will make the egg float. Â For health reasons, bad eggs that float should immediately be safely discarded.