BRIEF: The Science of an Airy Meringue -- With Chickpeas

(Inside Science) -- There’s nothing quite like the sweet, delicate airiness of a meringue. You can make it yourself by whipping together egg whites and sugar, with an optional dash of cream of tartar. When you beat the egg whites, the proteins unfold into a network that holds the newly formed air bubbles. The whites are 90 percent water, which dissolves the sugar and creates a kind of glue that keeps the foam together. Still, the foam might collapse -- which is why many recipes include an acid like cream of tartar. The acid helps the proteins unfold more easily and holds the network structure in place. When you bake the foam, the egg white proteins change irreversibly, becoming solid.

But say you’re vegan, or are simply out of eggs. What to do? Substitute chickpea liquid, it turns out. As vegan chefs have found, you can just use the liquid in a can of chickpeas, which are also called garbanzo beans. The liquid contains starch, proteins, and a type of foaming agent called saponin. One side of the saponin molecule clings to water while the other side doesn’t. Similar to the way soap makes bubbles, the molecule forms a barrier between water and air, reinforcing the bubbles in a foam.

And don’t worry -- your meringue won’t taste like hummus. In a taste test, Minh Vy Tran Nguyen and Eric Stemp of Mount Saint Mary’s University in Los Angeles found that most test subjects couldn’t tell the difference. “That was the real surprise,” Stemp said at a meeting of the American Chemical Society in San Francisco this week. “That’s not always the case when looking at food substitutes.”

Next, the researchers want to probe the properties of the molecules in egg whites and chickpea liquid -- and identify what gives meringue its magic.