Why do eggs spoil even though they have a hard shell?
The egg shell is porous so that air, moisture and bacteria can pass through the egg shell. Over time the egg loses moisture and the air cell becomes larger. These eggs are not as fresh and are best used for hard-cooking and baking. If the shell is dirty or cracked then bacteria on the outside of the egg can slowly pass through the egg and cause it to spoil. Eggs should always be kept refrigerated to prevent any bacteria from growing. The “Best Before” date on the carton can help you determine the freshness of your eggs.
