On Food and Cooking

peak stage, the foam is even firmer, takes on a
dull, dry appearance and crumbly consistency,
and begins to leak some liquid, so that it slips
away from the bowl again. At this “slip-and-
streak” stage, as pastry chef Bruce Healy
describes it, the protein webs in adjacent
bubble walls are bonding to each other and
squeezing out what little liquid once separated
them. Pastry makers look for this stage to give
them the firmest foam for a meringue or
cookie batter; they stop the incipient
overcoagulation and weeping by immediately
adding sugar, which separates the proteins and
absorbs the water. They also start the beating
with about half the cream of tartar per egg
that a cake or soufflé maker will, so that the
foam will in fact progress to this somewhat
overwhipped condition. Past the slip-and-
streak stage, the foam begins to lose volume
and get grainy.
Egg foams can be used on their own or as
the aerating ingredient in a variety of