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.
Copper bowls and eggs in the 18th century.
This is a detail of “Pâtissier,” or “The Pastry-
cook,” 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.”
The Effects
of Other Ingredients