We swear it’ll seem a lot simpler once you crack into the science behind it.
Though whipping egg whites may look pretty straightforward, learning the proper technique for whipping egg whites and the science behind it is a rite of passage for most cooks, especially those who bake. That’s because egg whites make cakes and other desserts (like pavlova, lemon meringue pie, chocolate mousse, or souffle) rise and keep them light and airy.
The volume and texture of your egg foam makes the biggest difference in desserts: over- or under-beating egg whites can result in weepy meringues, for instance, or an overly dense angel food cake. The good news is that anyone can whip the perfect fluffy foam—with up to eight times the volume—for angel food cake with a little science and a few tips.
Stock Up on the Right Ingredients and Equipment—Then Prep Them
First step is using the right equipment. Enlist a glass, ceramic, or metal bowl—that thin, oily residue that forms on plastic could prevent your whites from whipping properly. You’ll 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 as any grease, grime, or food residue can affect the volume of your whites.
Next up is the eggs themselves. Fresh eggs will 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 will give you more volume, so give your whites around 30 minutes of time out of the fridge before you start. In a pinch, you can let them rest a bowl of warm water for five minutes. The ideal temperature is 70 degrees.
Quick tip on egg separating. Though egg whites are able to incorporate more air at room temp, they’re easiest to separate when they’re cold. So if you want to get the best of both worlds, separate your eggs fresh out of the fridge, then allow the whites to warm up a bit. Whatever you do, do not let any yolk leach into your whites—this will prevent them from whipping properly.
Simple as this: start slow, then speed up as your whites become foamy and frothy. Then increase the speed to high until they reach the desired stage. 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, it’s important to note that eggs whites are made up of about 90 percent water and 10 percent protein. When whites are whipped, tiny air bubbles get distributed throughout their water-protein mixture, which causes the proteins to denature (i.e. their amino-acid chains uncoil). The newly unfolded proteins then situate themselves between the air bubbles and water molecules, which helps to strengthen the air bubbles’ walls. The longer the egg whites are beaten, the tighter the proteins bond together. At their peak (see what I did there?), egg whites can get up to eight times their original volume.
Stages of Whipping Egg Whites
When you choose to stop whipping is KEY. As you whip your whites, they’ll reach various stages.
First they’ll be foamy. You’ll see primarily liquid with some bubbles, and they’ll look just slightly opaque.
Then comes the soft peak stage, when they’re white and hold their shape. When you lift your beaters out of the bowl they’ll form soft peaks and the whites will curl over to the side.
Next, firm or stiff peaks. When you lift your beaters out of the bowl, the tips should stand straight and won’t bend over. This is when they’re at their peak volume—don’t beat past this point!
The final, sorry stage is over-whipped whites, which are grainy, watery, and flat. This is because the matrix of proteins in the whites has begun to break down and the foams are collapsing, and all that air you just whipped into them escapes. 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. 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 their full volume. So 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 to add the sugar, because it dramatically increases the beating time required to get good volume. That being said, it also helps preserve the structure of the egg proteins which makes it a lot harder to over-beat them (and adds a glossy appearance). Finding the right balance between these two is key, and explains why we add it gradually, and only after we’ve already 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 ingredients is to be gentle. This is why we delicately fold in our egg whites versus dropping them into our stand mixer and going to town—aggressive stirring would cause them to lose all 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 feels excessive. But this step adds to the light-and-airy texture that angel food cake is known for—it’s the same reason we use whipped egg whites. You’ve already made it this far, so why not aim for perfection?