Sometime around 1650, bundled straw began to be used as a stirring utensil, and when applied to eggs, had the effect of getting more air into the matrix of egg white goo than a simple stick that would have been used for stirring. Egg “snow,” so named back then, is a miraculous substance. You start with a single egg white, whip vigorously, and soon you have a big pile of fluffy egg white foam about eight times its original volume that can be cooked and eaten alone in meringue or folded into other ingredients, such as in mousses, soufflés and angel food cake, to give them tremendous lift and a delicate texture. Recipes that rely on egg foams will vary depending on the final result, but the basic job always goes something like this.
1. Separate Eggs. The best way to separate eggs is to start with fresh, cold eggs. They separate more easily than old or warm eggs. The best way to get a clean break when cracking eggs is to smack their sides on a countertop rather than a sharp edge. Then begin to pour the contents from one half of an eggshell into the other, back and forth. A bowl placed beneath your hands will catch the white, and the yolk will stay in the shells until you pour it out.
If, like me, you like to inject a little silliness into your cooking, you might want to get a weird but incredibly handy egg separating tool called the It ‘sNot-a-Mug, in which the egg white comes out of a ceramic face shaped like a mug through its nostrils — like snot. Weird, yes. I received mine as a gift years ago, use it all the time and laugh every time.
When making egg foams, it can sometimes be helpful to whip egg whites at room temperature and to use aged egg whites that have partially dehydrated. To achieve both ends, separate your whites 2 or 3 days before you intend to use them, and store them in the refrigerator in a partially lidded, but vented, container. Then bring the whites to room temperature about an hour before it’s time to use them.
2. Beat Eggs. An egg white foam consists of numerous tiny bubbles of air surrounded by a thin layer of liquid. Egg whites contain water, and water won’t foam unless it meets other particles that interfere with its liquid surface tension. The proteins in egg whites can rise to the occasion, but in order for them to unfold and bond to one another in a network that will hold both water and air in suspension, they must first be interfered with mechanically. A stand mixer will do the job, but not as well as a handheld mixer that will allow you to maneuver it in different directions in order to work more air into the mixture. A big balloon whisk also works well, if your wrists are up to it. You’re trying to encourage protein bonds, but there is one kind of bond that can be too strong to allow a foam to build, and that’s a sulfur bond. The classic tools for making egg foams are a copper bowl and copper whisk, because copper forms bonds with sulfur compounds, eliminating those compounds in eggs from wreaking havoc on your meringue. Fortunately for anyone who can’t afford copper kitchen equipment, an inexpensive acid, such as cream of tartar, can help achieve the same result.
Always use meticulously clean and dry utensils and mixing bowls when whipping up egg foams. Be sure there’s no trace of yolk in your egg whites. Fats and detergents are egg foam enemies. Begin by beating slowly until you start to see foamy bubbles forming.
3. Add Acid. Add about one-eighth of a teaspoon of cream of tartar per egg, as soon as you begin to see foam. Sometimes you’ll also add salt, but it’s best to add salt to the other ingredients of a recipe when possible, such as into the chocolate mixture for a chocolate soufflé, rather than into the egg white foam. Salts can decrease the stability of the foam.
4. Beat to Soft Peaks. Increase the mixing speed until soft peaks remain when you lift the beaters, and then pretty quickly fall over. Some recipes requiring egg foams might stop here at the soft peak stage.
5. Add Sugar. Gradually add granulated sugar or a sugar syrup. Sugar strengthens the networked walls around your bubbles.
6. Beat to Stiff Peaks. Continue beating your mixture, and eventually you’ll have glossy, firm, stiff peaks. I always find it surprisingly delightful to watch gooey egg whites make it this far. The network of liquid and protein is now stretched sufficiently thin to hold a great volume of air. When you take the beater or whisk away, a peak will stand up on its own. The glossy stiff peak stage is gorgeous.
7. Mix and Fold Carefully. If you’re adding your egg white foam to another recipe, as in a soufflé, always fold gently in big swaths to avoid damaging the voluminous mass you’ve just created.
For more egg recipes, check out Egg Recipes: The Incredible Versatility of Pastured Eggs.