Which process can be observed when cooking an egg, showcasing protein denaturation?

When cooking an egg, the process that showcases protein denaturation is when the egg hardens. This occurs because the heat causes the proteins in the egg white and yolk to unfold and reorganize, leading to a solidification of the egg's structure. As the egg is heated, the proteins lose their natural structure, a process known as denaturation, and then begin to coagulate, which is when they form new bonds and create a firmer texture. This is why cooked eggs transform from a liquid state to a solid one, demonstrating the fundamental principles of protein behavior under heat.

In contrast, if the egg remained liquid, it would indicate that denaturation did not occur. Dissolving completely would not happen under typical cooking conditions, as the proteins would need to be denatured to interact with water and form a solution. The darkening of the egg's color can occur during cooking due to Maillard reactions or caramelization but does not specifically illustrate the denaturation of proteins. Thus, the hardening of the egg effectively represents the physical and chemical changes involved in protein denaturation during cooking.