Cooking an egg changes its texture because heat makes the proteins bond into a firm network.

The longer version

Egg proteins are long chains folded into compact shapes held by weak bonds. Heat makes the chains vibrate enough to break those bonds, so the molecules unfold and then bond to one another, forming a continuous network that traps water. As that mesh tightens, liquid egg turns opaque and firm.

Push the temperature further and the mesh squeezes out enough moisture to feel rubbery. The temperature at which different proteins set varies, which is why the white solidifies before the yolk does. Acid and salt shift the setting point slightly by changing how the exposed chains interact with each other.

Where this entry sits

Everyday ingredients turn out to be full of quiet chemistry and long history. This collection gathers short, plain explanations of how bread rises, why onions sting, where common spices originate, and how coffee, tea, and chocolate reached the modern kitchen. The full list sits on the Food and Drink page, where every entry is listed in order.