Albumin is an umbrella term for a type of protein which is water soluble. Numerous types of albumin can be found all over the natural world, and two of the most familiar examples of albumin can be found in egg whites and in human blood. Albumins are an important class of protein, and they are vitally important to health and well being for many organisms. Many plants and animals contain or secrete albumin.

A protein classified as albumin is globular, meaning that it is soluble in water. Globular proteins also have a roughly spherical structure. When combined with water, albumin and other globular proteins form a colloid, a solution which appears homogeneous although it actually contains multiple substances. The other type of protein, fibrous protein, such as that found in muscles, is not water soluble, and it has a different basic structure.

Within the human body, albumin is an important component of life. Albumin in the human body transports essential fatty acids from adipose tissue, otherwise known as fat, to muscle tissue. It also contributes to the regulation of osmosis, helping to transport hormones, drugs, and other substances through the blood. An albumin deficiency can lead to medical issues. A doctor may request a blood albumin test to learn more about a patient's medical condition.

Technically, the albumin found in egg whites is more formally known as ovalbumin. This should not be confused with albumen, which is another name for egg whites in general. A little more than half of the protein found in egg whites are ovalbumin.

When heated, albumin and other proteins tend to coagulate. This property proves very useful in cooking, and is one of the reasons why eggs are so frequently used in baking. The protein helps baked goods hold their structure. The albumin in egg whites is also used for purification, as it tends to trap and store impurities. Egg whites are used to refine dishes like soup, and to treat people with certain types of poisoning, since the albumin binds to the toxin.

When it is cooked, the proteins begin to unfold, recombining in a new configuration; it also turns white and opaque. When beaten, the ovalbumin unfolds partially, creating a filmy foam which encloses pockets of air. As anyone who has beaten eggs too much is aware, when the proteins are beaten too much, they unfold completely and lose structure. Since albumin is flexible, it expands with the air trapped inside the pockets as it bakes, and it will retain the larger shape and yield a light, fluffy texture.