Science has proven a fact that chefs and
cooks have long known - copper bowls produce a specific reaction with egg
whites, producing a foam with greater volume and stability. In order to
obtain the maximum volume from whipped egg whites, with or without a
copper bowl, all traces of fat must be eliminated. Fat (including that
contained in the yolks and any grease on the bowl or whip) inhibits
foaming. Rinse bowls and whips with white vinegar to remove grease and
then rinse well with hot water.
Egg whites will whip to a greater volume if
they are not very cold. They can either be very gently warmed over
simmering water, or they may be allowed to come to room temperature for
about 30 to 45 minutes before whipping. The method is as follows -
Begin whipping the egg whites by hand or
machine at moderate speed. Tilt the bowl to make whipping by hand easier,
resting the bowl on a folded towel to prevent slipping.
When the whites are quite foamy, increase
Whip to the appropriate stage. Ingredients
like cream of tartar or sugar can be added to the foam as it develops. It
is generally not recommended that they be added before at least the soft
peak stage is reached.
Soft peak - when the whisk or beater is
pulled up through the egg whites, a droopy, rounded peak will foam. At
this stage, the surface of the whites looks moist and glossy.
Medium peak - Whites beaten to the medium
peak stage have a moist surface and form a rounded but fairly stable peak.
At this stage, sugar and other flavorings may be added.
Stiff peak - when the whisk or beater is
lifted out of the egg whites, they will stand up in stiff, stable peaks.
It is crucial to stop beating while the surface is still moist and glossy.
Over-beaten egg whites may still resemble those at the stiff peak stage,
but their surface looks dry and they have lost their elasticity. If the
whites are beaten further, the egg protein will gather into globs and the
moisture will weep out.