What is protein coagulation?

• A. A reversible folding of a protein
• B. A change in the structure from a liquid form to a solid or thicker liquid
• C. A reaction that breaks proteins apart
• D. A process of protein synthesis

Answer: (B)

Coagulation is when proteins in a liquid environment unfold and then link together to form a dense network, turning the liquid into a solid or thicker gel-like mass. Heat, acid, or other factors cause the proteins to expose new bonding sites; as these unfolded molecules bind to one another, they trap water and create structure. This is why eggs firm up when baked or custards set, and why milk can curdle or form curds under heat or with acid. It’s different from simply changing shape tentatively (reversible folding) or breaking proteins apart or making new proteins.