The Enemies of Egg Foams

Appears in
On Food and Cooking

By Harold McGee

Published 2004

  • About

Copper bowls and eggs in the 18th century. This is a detail of “Pâtissier,” or “The Pastrycook,” from the Encyclopédie, an engraving first published in 1771. The boy at right wields what the accompanying key calls “a copper bowl for beating egg whites and mixing them with the dough from which biscuits are made.”

There are three enemies to the successful mounting of a foam which the cook should be careful to exclude from the bowl: egg yolk, oil or fat, and detergent. All are chemical relatives, and interfere with foaming in the same ways: by competing with the proteins for a place at the air-water interface without offering any structural reinforcement; and by interfering with the bonding of the protein molecules. Traces of these troublemakers won’t absolutely prevent you from making a foam, but they’ll make you work harder and longer, and the foam won’t be as light or stable. Of course yolk and fat can safely be mixed with a finished foam, as happens in many recipes for soufflés and egg-leavened batters.