The volume and texture of your egg foam makes a big difference in desserts: over- or under-beating egg whites can leave you with a weepy meringue or an overly dense angel food cake. The good news is that anyone can whip up the perfect fluffy foam with a little science and a few tips.
The Right Equipment and Ingredients
First step: Use the right equipment. Enlist a glass, ceramic, or metal bowl; because the thin, oily residue on plastic could prevent your whites from whipping properly. You also need a stand mixer, hand mixer, or (for those willing to use elbow grease) a large balloon whisk. Make sure they’re perfectly clean and dry before you start because any grease, grime, or food residue can affect the volume of your whites. Next: the eggs. Fresh eggs give you the greatest volume because they’re slightly acidic, which helps stabilize the proteins (and as eggs age, they become more alkaline). Also, room-temperature eggs give you more volume, so take your whites out of the fridge around 30 minutes before using them or, in a pinch, at least let them rest a bowl of warm water for 5 minutes. By room temperature, we mean ideally 70 degrees. Quick tip on egg separating: Though egg whites can incorporate more air at room temp, they’re easier to separate when cold. For the best of both worlds, separate your eggs fresh out of the fridge, and then allow the whites to warm up a bit. Whatever you do, do not let any yolk leach into your whites—this prevents them from whipping properly.
The Method
Simple as this: Start slow, speed up as your whites become foamy and frothy, and then increase the speed to high until they reach the desired stage—peak volume. If you’re using a whisk, beat quickly in a circular motion to incorporate as much air as you can. So what’s happening here? First, eggs whites are about 90 percent water, 10 percent protein. When whipped, tiny air bubbles get distributed throughout this water-protein mixture, which causes the proteins to denature (that is, their amino-acid chains uncoil). The newly unfolded proteins then situate themselves between the air bubbles and water molecules, which helps strengthen the air bubbles’ walls. The longer egg whites are beaten, the tighter the proteins bond. At their peak (See what I did there?), egg whites can balloon up to eight times their original volume.
Stages of Egg-White Whipping
As you whip whites, they reach various stages; and knowing when to stop whipping is key. First, they’re foamy: primarily liquid with some bubbles, and slightly opaque. Then comes the soft-peak stage: They’re white and hold their shape. When you lift your beaters, the whites form soft peaks and their tips curl over to the side. Next come firm or stiff peaks: When you lift your beaters, the tips stand straight up and don’t bend over. This is peak volume—don’t beat past this point! The final, sorry stage is over-whipped whites: grainy, watery, and flat. The matrix of proteins in the whites has broken down, the foam has collapsed, and all that air you just whipped into them has escaped. Don’t let them reach this stage, because over-whipped whites cannot be salvaged.
Using Egg Whites in Angel Food Cake
In our angel food cake recipe, we whip the whites with cream of tartar first. This is because cream of tartar is acidic, which stabilizes the egg whites and helps them hold in water and air, which boosts their ability to reach full volume. If you’re using older eggs, this step is particularly crucial. Remember to wait until your egg whites have already reached the soft peak stage before adding sugar. (Otherwise, it dramatically increases the beating time required to get good volume.) This helps preserve the structure of the egg proteins, making it a lot harder to over-beat them (and adds a glossy appearance). Finding the right balance is key, which explains why we add sugar gradually, and only after we’ve moved past the foamy stage. Once you’ve nailed your stiff peaks, the key component when incorporating them into the rest of your angel food cake batter is to be gentle. This is why we delicately fold in egg whites versus dropping them into our stand mixer and aggressively stirring, which causes them to lose their volume. To preserve their structure, use your egg whites immediately and gently fold them into the flour mixture in four separate batches with a rubber spatula. And yes, sifting the powdered sugar and flour together three times seems excessive, but this step adds to the light-and-airy texture that angel food cake is known for. You’ve already made it this far, so why not aim for perfection?
