On food and cooking the science and lore of the kitchen ( PDFDrive ) 209

Interpreting the Foam’sAppearance There
arevariouswaystojudgewhenthefoamisat
its optimum, from seeing whether the foam
willsupporttheweightofacoinoranegg,to
seeing how it supports itself, in soft mounds
orsharplydefinedpeaks,toseeingwhetherit
clings to the bowl or slips along its surface,
whether its surface looks glossy or dry. All
theseteststellushowcrowdedtheairbubbles
are, and how much lubrication they have
between them in the way of liquid from the
eggwhite.Anddifferentdisheswilldefinean
optimum foam differently. The lightening
powerofaneggfoamdependsnotjustonthe
foam’svolume,butalsoonhoweasilyitcan
bemixedwithotheringredients,andhowwell
it can accommodate bubble expansion in the
oven. Soufflés and cakes require the
lubrication and expansion tolerance of a
somewhat underbeaten foam, while in
meringuesandrelatedpastriesvolumeisless
importantthanshape-holdingstiffness.


Glossy Soft Peaks and Stiff Peaks At the
“soft peak” stage, when glossy foam edges
retain some shape but droop, and when the
foam doesn’t yet cling to the bowl, the
somewhat coarse bubbles are still lubricated
byplentyofliquid,whichwouldquicklydrain
tothebottomofthebowl.Atthe“stiffpeak”

stage, where the foam is still glossy but now
retains a well-defined edge and clings to the
bowl, the foam is approaching 90% air, and
theeggliquidhasbeenspreadsothinthatthe
proteinwebsinadjacentbubblewallsbeginto
catch on each other and on the bowl surface.
There’s just enough lubrication left for the
foam to be creamy and easily mixed with
other ingredients. This stage, or perhaps just
beforeit,istheoptimumformakingmousses,
soufflés,spongecakes,andsimilardishesthat
involvemixingandfurtherrisingintheoven.
Furtherbeatinggainslittleadditionalvolume.
Dry Peaks and Beyond Just past the stiff-