What does salt do to egg whites?

Salt is an important ingredient in meringues, angel food cakes, and other egg-white-based desserts because it helps the whites whip up faster, to greater volume, and with greater stability.

Slows Denaturation

Heat coagulates, or denatures, egg white proteins. But adding salt to egg whites delays the denaturation process, allowing the whites to be heated to a higher temperature without becoming rubbery. This is why salt is often added to boiled and fried eggs.

Strengthens Chemical Bonds

Heating egg whites with sugar causes the sugar molecules to bond with amino acid molecules in the egg white proteins, creating a stronger network. Salt reinforces these bonds, resulting in a foam that holds up better.