Mixing Speed Affects Whipped Egg Whites

Recipes engineered for perfection—what exactly does that mean? We take you inside Cook’s Illustrated’s science experiments.

When whipping egg whites into a foamy meringue, the usual approach is to start slow and build up speed for better volume. But how much of that matters in producing sky-high peaks?

THE BACKSTORY

Most recipes that call for whipped egg whites require that you start with a mixer on low and then slowly ramp up the speed in order to build volume in the egg whites. But we wondered how much of a difference the slow start actually made, so naturally, we took it upon ourselves to find out.

THE EXPERIMENT

We whipped up two batches of egg whites. In the first, we whipped the whites slowly until they were foamy (about one minute) and finished on high. In the second, we beat the whites at high speed the entire time. We then made meringue cookies, meringue frosting, chocolate mousse, and chiffon cakes with the two different batches.

The egg whites with the slow start produced a meringue that was about 10% more voluminous than the high-speed-only whites, resulting in a meringue cookie and frosting that were lighter and airier (the cookies were also larger). Both batches of mousse and chiffon cake, on the other hand, were indistinguishable from one another. Why was this?

It turns out that beating egg whites slowly at the beginning causes their proteins to loosen up. Like stretching a balloon before you try to blow it up, the improved elasticity allows the proteins to take on air more easily and eventually gain more volume. This extra volume makes a difference when meringue is the main element in a recipe, as was the case with our cookies and frosting. But when meringue is just a minor player that gets folded into a heavier batter or mousse, you can save time by whipping full speed ahead—your happy dessert-eaters won’t notice a difference.

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