The Science of Egg Whites

Egg whites are mostly protein. When whipped, those proteins unwind and thousands of tiny bubbles form, causing the egg whites to increase in volume by as much as six to eight times. As you whip egg whites, they initially become slightly frothy. Whip them longer and they become white and creamy, forming soft peaks and finally, stiff peaks. Whip them too much, though, and the bubbles collapse, the proteins bind together and the mixture becomes a grainy, watery mess, similar to what happens if you curdle milk products.

A Quick Fix

To repair egg whites that have been whipped too much, add another egg white to the bowl and beat gently. The proteins in the fresh egg whites help temper the meringue so it becomes creamy once again.

An Ounce of Prevention

Two simple ingredients can help stabilize egg whites so they whip up quickly and are less likely to break down. Whisk the egg whites for 30 seconds or so until they're frothy and then add a spoonful of cream of tartar. Continue whipping until soft peaks form. Add sugar at a rate of 1/4 cup sugar for each egg white. Super-fine sugar dissolves better than regular granulated sugar, but either variety works. Sugar not only sweetens the meringue and gives it a glossy sheen, but also provides stability.

It's in the Mix

To prevent overmixing, pay careful attention to how you prepare and whip the eggs. First, crack cold, fresh egg whites into a bowl and allow them to come to room temperature. Fresh eggs don't produce as much volume as older eggs, but they're more stable. Room temperature eggs whip up more quickly than cold ones. Use a clean metal or glass bowl -- not plastic -- and ensure that your whisk is clean. Tiny particles of fat can interfere with the whipping process. Watch the eggs closely as you whip them. They'll first form soft peaks, which hold their shape for a few seconds. As you whip them longer, they form stiff peaks. At this point, if you hold the whisk upside down, the peaks remain upright or curl only slightly. Whip the egg whites until they barely hold a stiff peak. Whip them longer and you risk ruining them. It's better to have slightly underwhipped eggs than to whip them too much.