Protein coagulation

Protein coagulation is the change in which heat turns liquid proteins, such as those in eggs, into a solid that cannot go back.

Protein coagulation: A smooth baked custard cut to show a clean, softly set, uniform pale yellow interior
  • Food science and baking chemistry

Also called: egg coagulation, setting

Coagulation is the transformation of proteins from a liquid state to a solid form, and once it happens the proteins cannot return to liquid. It often begins around 100 F (38 C) and is finished between about 160 F and 180 F (71 C to 82 C).

Egg proteins show it clearly. Egg white sets between roughly 140 F and 149 F (60 C to 65 C), while the yolk sets a little higher, between 144 F and 158 F (62 C to 70 C). That is why an egg can have a firm white and a soft yolk.

Mixing eggs into other liquids raises those temperatures. A custard of eggs, milk and sugar thickens at about 176 F to 185 F (80 C to 85 C) and begins to curdle at about 190 F to 194 F (88 C to 90 C), so bakers cook custards gently and stop before they overheat.

Related entries

Sources

Written by VanillaGoods in our own words from these sources. Last reviewed October 15, 2026.

  1. 1.1: Coagulation, LibreTexts Workforce (Modern Pastry and Plated Dessert Techniques)
  2. 1.4: Coagulation, LibreTexts Chemistry (Chemistry of Cooking)