The next stop on our Big Five Mixing Methods tour will be the Egg Foam Method. Of all the various mixing methods out there, the Egg Foam Method has the virtue of being the most direct, the simplest. For indeed, instead of spending time and effort to create the conditions most likely to produce gas bubbles (as with every other method), with the Egg Foam Method you simply whip them up yourself. The challenge then of course: to keep those bubbles from bursting.
The Egg Foam Method begins, unsurprisingly, with eggs. Usually just the whites, though it is possible to make egg foams using the yolks too (they don’t fluff up as well, but more on the reasons for that later). The eggs are introduced to some sort of whipping device — a stand mixer, hand mixer, or whisk. Air begins to be incorporated and before long, voilà, ze foam. The next step is usually to introduce some form of acid stabilizer (cream of tartar, say) before the foam is folded into the other ingredients in the recipe.
What do those air bubbles do in the, er…whatever-it-is? Just as with all other mixing methods, they leaven (or “push up”) the batter. Once again it’s not expanding air that accomplishes the task. Air only expands by 20% or so in the heat of an oven. Rather it’s the water in the batter that does it. As I mentioned last week, water expands to some 1400 times its original volume when it’s converted to steam. The steam blows up the air bubbles and bingo, you’ve got leavening.
Interestingly it’s the hand mixer, as opposed to one of the stand variety, that’s the best tool for making egg foam, since it allows you to chase down every last little pocket of unwhipped white (my big ol’ Viking mixer is terrible at egg whites). Of course you can do it by hand, but there are very few people out there with the forearm strength to whip up a mass of egg whites into peaks before some of the foam starts to collapse. I once knew a brawny Swede who could do it. That sweet old lady could have pimp-slapped a longshoreman unconscious. The rest of us mortals need machines.