Question

Egg whites are primarily composed of the protein albumin. one familiar example of the denaturing of proteins is the difference between the albumin structure in a raw egg versus a cooked egg. using what you know about the levels of structure in proteins, propose an explanation of changes in albumin (and other proteins) that occur during cooking

Answer 1

Answer: Egg proteins change when we heat, beat, or mix them with other ingredients. Proteins are made of long chains of amino acids; in an egg white these are globular proteins which means that the long protein molecule is twisted, folded and curled up into a spherical shape. To keep the protein in that shape there is a variety of weak chemical bonds which keep the protein curled up tight as it drifts placidly in the water that surrounds it.

Answer 2

When an egg is heated (without the shell in a pan, the yellowish and translucent liquid becomes white and rubbery, the egg yolk becomes solid.

When we heat the white and yellow of an egg, we can observe that the liquid becomes solid. It is said that the egg has coagulated, or else that it has cooked. The proteins of the egg (yellow and white) are at the origin of this coagulation.

White is made up of 12.5% of a protein of the albumin group: ovalbumin, which represents more than 50% of the total protein of white. It is composed of four acid chains amines, which give it a globular form.

When the temperature approaches 60 ° C, the atomic agitation becomes such that the bonds weaker, like hydrogen bonds, break. The protein runs and becomes a long chain of amino acids: this is the denaturation.  

In this denatured state, some parts of the protein become accessible and can to meet other protein molecules, with which they will associate. This association of proteins by disulfide bridges is responsible for the phenomenon of coagulation. In addition, the binding of the proteins together reveals a network that traps the water molecules, causing the stiffening of the egg after cooking.