Whip it real good
It may seem like an annoying extra step, but believe me that if a recipe is calling for whipped egg whites, you’re going to want to do as you’re told (that’s sort of the point of following a recipe, you know). Egg whites are little more than puddles of water with tightly coiled balls of protein floating in them. Those proteins are the things that hold your muffins together and make your quiche custards set. They’re also the things that capture air when worked into a frenzy, forming protective little protein balloons that are inflated by the power of your whisk. When you whip eggs into a cloud of foam, you open your world to some serious breakfast magic: extra fluffy pancakes, omelets so light they could float into space, airy Belgian waffles eager to suck up maple syrup.
Here are some egg whipping tips that will help guarantee success:
Mind your yolks
Foams are delicate structures that build one bubble at a time, standing on each other's backs. If even a tiny drop of fat is in the pool, those baby bubbles are just going to slip and slide off of each other; picture a bunch of greased up cheerleaders attempting to form a human pyramid. The number one source of accidental interloping fat: egg yolks. If you accidentally pierce a yolk while separating, you’ll never be able to get a foam to form, no matter how vigorously you whip. Save yourself the pain. Separate your eggs one at a time in two small bowls, then move your clean whites to the big whippin’ bowl.
Your bowl, too
Whites need to be whipped in a very clean glass or metal bowl, never plastic. On a molecular level: picture fat as a plug and plastic as a socket. Those two things can’t help bonding once they’ve touched each other, so no matter how well you wash a plastic container, it will always have a microscopic layer of fat on it and foil your foaming plans.
You may have heard that it’s best to whip egg whites in a copper bowl, which is true: copper contains ions which can help prevent over-whipping. But who has a copper bowl just for egg whites? Please don’t let an overpriced kitchen supply store convince you that you need one when you can achieve the same results with a teeny, tiny pitch of an acid like cream of tartar or a drop of lemon juice. It will lower the pH, reduce the risk of disulfide bonds from forming (They are the enemy! BOO! HISS!), and let you worry a bit less about over-whipping.
When to stop
This step is everything. If you’re whipping by hand it’s going to take some time, but you’re going to want to see this through to the right moment. If you’re using a mixer it’s easy to overshoot, causing those proteins to wring out all their water like a sponge, giving you a dry, grainy foam. So let’s pay attention here: if you're putting in the effort, I don’t want you to be disappointed.
There are three common foam instructions in recipes: frothy, soft peak, and firm peak.
Frothy: You shouldn’t be able to see any “loose” egg white. It should be uniformly white and bubbly, but look so delicate that it could deflate any moment.
Soft peak: The whites will have a good amount of volume, and you’ll begin to see peaks form while moving your whisk through it. Pause a second, lift your whisk straight up and point it to the ceiling: if you have a peak that’s holding its shape but drooping a little bit at the top, you’re good. If it collapses completely, keep going.
Firm peak: Same thing as soft peak, but instead of having a mildly droopy peak, the whole thing will stand straight up at attention. If you accidentally have reached this point when you wanted soft peaks, do not fret. Just add a few more folds when incorporating your whites into your batter and you’ll be fine.