Answer: Egg White

They create the distinctive white ring around fried eggs, they’re whipped into meringues, patients worried about cholesterol intake are advised to eat them alone sans the yolk, and they’ve even been used in bookbinding and printmaking over the years. Egg whites are a protein rich and surprisingly diverse component of bird eggs.

Although we simply call the substance “egg white”, its technical name is albumen. The name is derived from the term “albumin”, the class of water-soluble and sulfur-containing proteins found in abundance within the white of the egg as well as in other organic tissues like muscle and blood.

When nature takes its course and the egg is fertilized, the albumen serves as a protective cushion for the yolk and the growing bird attached to it as well as providing nutrients to said bird. When we encounter the albumen in unfertilized eggs used for cooking, we get to experience a fun little science experiment in every meal. When you cook an egg, be it by boiling it, frying it, or otherwise preparing it with heat, you witness the denaturation and unfolding of the albumin proteins. As the proteins unfold and the albumen solidifies, it turns white and becomes denser. If you’ve ever overcooked your fried eggs and noted their rubbery texture, that texture is a result of fully denaturing the proteins found therein.