Here are the stages of egg whites you’ll find called for in recipes.
Foamy or frothy. This is the first landmark when beating egg whites. Often a recipe will have you beat on low or medium-low until foamy before increasing the speed (more below). Look for the whites to be pretty universally bubbly and not just on top.
Soft to medium peaks. As egg whites transition to soft peaks, they’ll go opaque and turn cloudlike. Look for the whites to start holding the trail of the whisk or beaters. If you tilt the bowl, liquid will flow to the bottom and the foam won’t cling to the sides, McGee says. The lines between soft and medium can be blurry depending on whom you ask, but soft peaks will flop over, either into a mound or a droopy tip, while medium will retain a more curlicue shape, Erin Jeanne McDowell writes in “The Fearless Baker.”
Stiff or firm peaks. At the stiff phase, “the foam is still glossy but now retains a well-defined edge and clings to the bowl,” McGee says. Whites beaten to a stiff peak will stand straight up, whether you’re looking at what’s on the beaters or in the bowl.
Overbeaten. If you’ve gone too far, “the whipped mixture goes from glossy and cloudlike to grainy and matte, liquid seeps out of the whites to the bottom of the bowl, and the whole mess starts to resemble Styrofoam,” Joanne Chang and Christie Matheson say in “Flour.” At this point, it’s time to start over.
And now some best practices to help you get it right every time.
McGee says to keep three things out of your egg whites: yolks, oil/fat and detergent (soap). “Traces of these troublemakers won’t absolutely prevent you from making a foam, but they’ll make you work harder and longer, and the foam won’t be as light or stable,” he says. So wash and rinse your bowls and beaters well, and inspect them before you start cooking.
Carefully separate the yolks from the whites
When warm, egg yolks are more likely to break and contaminate the whites, Shirley O. Corriher says in “CookWise,” so separate them cold out of the fridge. (Colder whites can take longer to foam, but they’ll warm up quickly enough in beating, especially with an electric mixer.) If you’re separating multiple eggs, designate a bowl just for separating and then larger ones to stash the yolks and/or whites you’ve already separated. That way, if you mess up one egg and break the yolk into the white, you only have to toss (or, better, save for scrambled eggs) one rather than the whole batch. More on how to separate in my piece from last year.
Acids prevent proteins in the whites from bonding too much, which can cause the foam to collapse and squeeze out water. Per McGee, before beating, you can add 1/8 teaspoon of cream of tartar or 1/2 teaspoon lemon juice per egg white to ensure stability. In “The Baking Bible,” Rose Levy Beranbaum recommends increasing the cream of tartar to 1/4 teaspoon if you’re using whites from pasteurized whole eggs, and Corriher says 1/8 teaspoon of distilled white vinegar is an alternative to the cream of tartar. Some cooks swear by using copper bowls to achieve the same result — though Corriher notes that in an experiment, copper bowls had more of an impact on the volume of the final baked dish rather than that of the beaten egg whites — but they are somewhat tricky to maintain and expensive to buy.
Start beating the egg whites gradually
Starting your mixer on low and slowly increasing the speed not only is neater, but also has the benefit of improved results. “Beating egg whites slowly at the beginning causes their proteins to loosen up. Like stretching a balloon before trying to inflate it, the improved elasticity allows the proteins to take on air more easily and eventually gain more volume,” according to Cook’s Illustrated. This is most important when a meringue is the star of a dish, such as in cookies or frosting. A meringue started on low was 10 percent more voluminous than one started on high speed.
If you are beating egg whites with sugar to make meringue, don’t add the sugar at the beginning. Including sugar early on can delay foaming, McGee says, which will be especially noticeable when beating by hand. Add the sugar gradually once the whites have reached soft peaks, Corriher says, though it’s okay to err on the side of too early, which will just make the beating process a bit longer, versus too late, when your egg whites may be too dry to incorporate it well. As to type, McGee notes that superfine/caster and confectioners’ sugar (not everyone loves its starch) dissolve most readily, whereas granulated can make a gritty meringue. Make your own superfine sugar by processing granulated in a blender or food processor.
Be mindful of pasteurized eggs and whites
I’m sure I’m not the only one who has thought liquid egg whites would make my life easier only to witness the opposite. As America’s Test Kitchen explains, the heating that takes place in pasteurization causes the egg proteins to start bonding before you’ve even done anything, making unfolding and stretching them even harder. Expect pasteurized egg whites to take much longer to foam (13 minutes versus 2 minutes for a medium-stiff meringue in our Summer Fruit Semifreddo, for example), and be prepared for a less voluminous result, as well.