The Science Behind Egg White Cocktails
Raw egg whites have long been an integral part of cocktails, responsible for the prized frothy head on drinks like the tart Pisco Sour and the fruity Clover Club. While we’ve previously explained why you shouldn’t be afraid of raw egg whites, understanding why bartenders use egg whites in the first place requires a bit of chemistry. (Don’t worry if you snoozed through high school science. It’s all easy-to-understand metaphors from here on out.) We talked to our favorite egg scientist, Dr. Deana R. Jones, research food technologist with the Egg Safety and Quality Research Unit at the USDA Agricultural Research Service, to get a look inside the shaker tin at the science of egg whites in cocktails.
Why Egg Whites Go From Clear to WhiteThere’s a lot more than mixing going on in the shaker when you add egg white to the mix. The texture and volume of the mixture are changing, and it’s all thanks to the proteins inside the egg white. “Even though albumen [aka egg white] is a clear, viscous fluid, it’s actually made up of a whole lot of proteins,” Jones explains. “The whole reason it’s clear is that the [proteins] are tightly wound—they’re bound on top of each other.” But smacking them around in the shaker causes them to unwind and reconfigure. “The reason the albumen turns from a clear fluid into a white substance—whether it be when you’re cooking it, or when you’re beating it and it becomes a fluffy white foam—is because the proteins begin to unwind and stretch,” Jones says, comparing shaking to waking up the proteins in the morning, causing them to yawn and stretch out. “As they start stretching, they start holding onto each other’s hands, in a way. They start forming a network, and that’s when it starts to turn white.”
Why Egg Whites Get Fluffy“We’re talking about aeration,” Jones says, pointing out that the same chemical change happens when you whip egg whites with a whisk. “As the proteins unfold and hold each other, they’re hugging an air bubble. They’ve made this air bubble that they’re all wrapping their arms around. As long as they keep holding hands, they’ll keep that air bubble stable.”
When you have enough proteins making rings around air bubbles, the proteins form a network, changing the composition of the liquid and increasing the volume, which is why you’ll see that sizeable foamy head on top of a drink. While the exact amount of expansion varies based on a lot of factors, Jones says, “in a perfect scenario, it can easily grow over 10 times in volume.”