Meringue Chemistry: The Secrets of Fluff

Chefs began whipping up meringue sometime in the early 1600s. The light-as-air confection is made by whipping egg whites and is used in a variety of desserts, such as Pavlova, macaroons and baked Alaska. It’s a delicacy that’s delightfully counter-intuitive. While most other foods get smaller and flatter as they’re beaten and smashed, egg whites are comparatively resilient and fluff up and expand under similar duress.

This past weekend I had a few egg whites left over after making another dish and thought I would try my hand at them. If these things were made by Renaissance chefs in the days before electric hand mixers, surely I could manage to whip some up myself. Unfortunately, mine were a flop—literally. The egg whites never puffed and peaked like they were supposed to; they sat in flat, unappetizing pats on my baking sheet. How could something seemingly so simple fail so spectacularly? Turns out there’s a lot of chemistry to consider when making meringue.

Although egg whites are 90 percent water, the relevant molecules are protein. Proteins are made up of amino acids, some that are attracted to water, others that are repelled by water. One you start beating the whites and introducing air, the water-loving bits cling to the water, the water-repelling bits cling to the air. The more you beat, the more bubbles with a protein coating are created and the more the whole shebang fluffs up. However, bubbles and proteins divided against themselves will not stand, and the foam will collapse without a little stabilizer. One way of doing this is to introduce an acid such as vinegar, lemon juice or cream of tartar, which encourages the proteins in the egg white to bond together. Another ingredient that adds structural integrity, in addition to providing flavor, is sugar, which works like a glue that holds the foam together.

But why don’t we want to use the yolk? This part of the egg contains fat, which interferes with how the proteins line up and coat all those bubbles that are supposed to bulk up your meringue. If the bubbles aren’t properly protected, your meringue will never have much body. This is also why chefs are discouraged from using plastic bowls for this purpose as they have a tendency to retain oils. So perhaps I wasn’t as careful as I ought to have been when separating my eggs and a bit of stray yolk made it into my whites. I’m also in the habit of using my hands to separate eggs. And even though I washed my hands beforehand, perhaps residual oils sabotaged my baking venture. So even though my first try didn’t go so well, tell us about your meringue adventures (or misadventures) in the comments section below.

Jesse Rhodes | READ MORE

Jesse Rhodes is a former Smithsonian magazine staffer. Jesse was a contributor to the Library of Congress World War II Companion.