An egg can be frozen safely, but because the white and the yolk behave differently, their texture will differ when thawed. The yolk is largely made up of fat, while the white consists mainly of protein. In addition, each will behave differently, depending on whether it is frozen while raw or cooked.
Raw vs. Cooked Eggs
According to the USDA Food Safety and Inspection Service, freezing creates large ice crystals that damage cells during thawing, thereby altering texture. Freezing egg yolks and whites can cause quite dramatic changes, depending on whether they are raw or cooked. A raw egg yolk will gel and become difficult to blend with other ingredients. In contrast, a raw egg white freezes well. A cooked egg yolk will freeze well, unlike a raw one. However, a frozen cooked egg white changes texture so that it becomes rubbery.
It is best to blend an egg yolk with the white before freezing them in a closed container. Separating the egg will also work. A yolk should be broken with a pinch of salt or sugar mixed in before freezing to preserve its texture. An egg white does not require special treatment. Yolks and whites can then be frozen singly in separate compartments of an ice cube tray, then transferred to a container or freezer bag.
Thawing and Using
For larger volumes, break and stir 1/2 cup of yolks with 3/4 tsp. sugar or 1/4 tsp. salt before freezing them in a single container. Putting whites together in one container is fine, too. Once thawed, whole eggs or yolks will typically not provide the same leavening for baked good as fresh eggs and yolks, so they should probably not be used for dishes like souffles, where "lift" is important. On the other hand, frozen egg whites should produce much the same results as fresh ones, once thawed.
It's best to use whole frozen raw eggs, whites or yolks within one year. The temperature of a freezer should be kept at 0 degrees F or lower. Cooked dishes that contain eggs will vary in taste and texture, once thawed. It depends on the ingredients in a dish and the packaging. As a general rule, dishes containing eggs should be eaten within three months. Any thawing is best done in the refrigerator to retard the growth of bacteria.