materials that interfere with the free
movement of water molecules, and thereby
slow the drainage and thinning of the bubble
walls. Foam stabilizers include the
microscopic particles in purees, proteins,
thickening carbohydrates like starch, pectin,
and gums — and even emulsified fat. Free fat
or oil is a foam killer, because the fat spreads
at the interface with the air — it’s chemically
more compatible with air than with water —
and prevents emulsifiers from settling at the
interface and stabilizing it. However, if the fat
is emulsified — for example in an egg yolk or
yolk-based sauce — then it remains dispersed
in the water phase, and its droplets only
interfere with the flow of liquid from the
bubble walls.
Heat-Stabilized Foams: Sabayons Both the
method and the name of the French sabayon
derive from the Italian zabaglione, a sweet,
winy foam of egg yolks (p. 113). Though rich