Albumen is the clear substance that surrounds the yolk of an egg. When it is beaten or cooked, it looks white and may be called an egg white, puggle, or glair. This substance is distinct from albumin, which are proteins that are water soluble and found in a variety of creatures — humans have albumin in their blood plasma for instance. Egg whites, to make matters more confusing, contain certain proteins that are dissolved in water. The typical egg white contains about 15% protein and about 85% water.
In cooking, albumen is an important element. Recipes for cakes, pancakes, and waffles often call for separating the white from the egg yolks, and beating it until it forms soft peaks. It is then folded into the recipe ingredients, creating very fluffy results. Some cakes, like the angel food cake, rely solely on whipped egg whites and don’t use the yolks at all.
Albumen proteins are elastic and tend to bond easily with other proteins. For example, when a chef whips egg whites in a copper bowl, copper atoms bond with the proteins. The whites become frothy meringue because whipping them causes the protein molecules to stretch to accommodate air whipped in.
When whipped to create meringue, this substance is common to mousses and souffles, and it may be used in certain types of frostings. Stiff meringue can be baked into cookies or ladled onto the tops of pies. Albumen that is only slightly beaten is a common alternative to eating whole eggs. Egg white omelets are especially popular and a good way to cut down on saturated fats in the diet, because most of the saturated fat in eggs is in the yolks.
To avoid cholesterol, people may choose to use only egg whites for breakfast foods or baking. There’s actually some debate as to whether a few whole eggs a week, yolk and white, is unhealthy. Recent research suggests that yolks actually lower bad cholesterol and raise good cholesterol, even though early understanding of cholesterol resulted in demonizing many food sources like the egg. Unless a person is dieting or attempting to lower a dramatically raised cholesterol score through diet, eating a few whole eggs a week may be healthy.
When the whites are not whipped into meringue or prepared as breakfast eggs, they can be separated from the egg yolks and used as way to glaze items baking in the oven, often called an egg wash. Manufacturers treat beer and wine with albumen to remove sedimentary deposits. It is also often listed on broth that can be bought at the store, and many recipes call for egg whites to help clarify or make the broth clear.