Emulsions
We’re going all the way back to middle school science class today.
An emulsion is a stable mixture of two or more things that would not naturally mix or dissolve into one another. Usually those two things are fat and water when it comes to baking. And you might not have realized it, but you form an emulsion every time you mix up cake batter, frosting, or cookie dough.
They’re tricky. I still struggle with them, especially frostings! But the more I understand about emulsions, the easier it is to figure out what went wrong and how to fix it.
And believe me, you’ll know if it goes wrong: the batter or dough will look like it’s separating, beading, or weeping, and instead of looking creamy, it could look like there are little chunks in it. This is called curdling, and you don’t want it to happen.
Why? What’s the big deal with curdling?
The severity of it is what matters. A little bit is fine for cake batter or cookie dough. In fact, if you’re making a butter-based cake, it’s normal for the batter to look a little curdled when it goes into the oven. But a lot of separation will affect the rise and texture on your baked good.
A slightly curdled frosting might be fine, too, as long as you aren’t going to pipe it. If you want to add color and decorate, you don’t want those beads on the top of your cake. A very curdled frosting will be loose and won’t stick to itself. I once had a badly split chocolate frosting slide right off the side of a cake!
So how do I keep my emulsions stable?
All ingredients should be at the same temperature, usually room temperature. The shock of adding cold ingredients can make a batter split. Try to take your everything out of the fridge out ahead of time to warm up on the counter. Or speed things up with the microwave (on low power) and by putting your (uncracked) eggs in a bowl of warm water for a few minutes.
Make sure you whip the butter first when making frosting. The smoother and more pliable it is, the more readily it will take to other ingredients going in. (For butter-based cakes and cookies, read my post on creaming.)
Emulsions break when the fat can’t hold the volume of liquid you’re trying to put into it. The more fat you have, the more water it can hold. Try a quality butter (Kerrygold, Cabot, or a European butter) with a higher fat content if you’re working with a tricky recipe or are a beginning baker.
Add liquid or oil gradually. The slower you go, the more gradually you try to change the composition of your emulsion, and the easier a time you’ll have incorporating that ingredient.
Add an extra egg yolk to a cake batter or cookie dough that tends to split. The yolks contain an ingredient called lecithin which helps stability.
Acidic ingredients like natural cocoa powder, buttermilk, or lemon juice can make emulsions break. Don’t use more than the recipe calls for.
Mixing vigorously can help stabilize frostings. Enough mixing can sometimes bring a curdled frosting back together.
With cake batter, the opposite is true. When you’re making a butter-based cake, over-mixing when the milk and flour go in can cause curdling. Not to mention you’ll make your cake tough and dry.
For frosting, you can try warming it if your butter was cold or popping it in the fridge if your kitchen is hot. Re-whip after 5–10 mins and see if it helps.
SOS!
If you can’t figure out what went wrong, talk to me. I would be delighted to help! Just email me at confessionsofacakesnob@substack.com or comment on this post.
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