How Proteins Destabilize Foams

Appears in
On Food and Cooking

By Harold McGee

Published 2004

  • About
The very same forces that make egg foams also break egg foams. Often just as the foam is reaching its optimum texture, it will get grainy, lose volume, and separate into a dry froth and a runny liquid. As the proteins bond to each other to support the foam, they embrace each other too tightly, and squeeze out the water they had held between them. There are several different kinds of bonds by which the long, unfolding egg proteins are joined to each other in a reinforcing network: bonds between positively and negatively charged parts of molecules, between water-like parts, between fat-like parts, and between sulfur groups. The protein network begins to collapse when too many of these bonds accumulate and the proteins cluster together too tightly. Fortunately, there are simple ways for the cook to limit the accumulation of bonds and prevent the collapse of albumen foams.