contribute much to the raw foam. But it is
sensitive to heat, which causes it to unfold and
coagulate. So when the raw foam is cooked,
ovalbumin more than doubles the amount of
solid protein reinforcement in the bubble
walls. At the same time, much of the free
water in the foam evaporates. Heat thus
allows the cook to transform a transient semi-
liquid foam into a permanent solid one.
How Proteins Destabilize Foams
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