Why do you have to put salt in meringue?

The addition of salt to the beaten egg-white mixture is primarily for flavor. But it's been found to have two other effects on meringues as well. But it's been found to have two other effects on meringues as well. First, salt promotes the coagulation of proteins, which means you have to beat the egg whites longer to unwind the bunched up (coagulated) protein strands and stretch them into the thin films that encase air bubbles and create foam. Second, if added too early, it decreases the stability of the beaten egg whites, which in turn weakens the protein network that forms the structure of the meringue.