The Science Behind Angel Food Cake

Angel food cake. Source: Tim Sackton, flickr.
Angel food cake. Source: Tim Sackton, flickr.
If you’ve ever made an angel food cake, you know how hard it can be to duplicate the chemistry involved in this cake. Since I didn’t understand the science behind the steps, I asked myself for years why my cakes were flat and chewy instead of tall and airy.

Angel food cakes are a balance of the scientific principles behind fluffy egg whites—the albumen of an egg—stabilized by sugar and low-protein flour.

This recipe calls for whipped egg whites because as the baker whips the egg whites together s/he incorporates air into them. Airy eggs are the backbone to a fluffy cake. When air is added to the egg whites, it denatures or relaxes the egg’s proteins. Stiff peaks in the egg whites tell the baker the proteins bonded together and captured the air. When the cake temperature reaches approximately 212 degrees Fahrenheit, the air bubbles grow and the batter cooks around them, according to “The Science of Angel Food Cake.” After the bubbles pop and the cake is done all the air pockets are still visible, but the cake needs to cool upside-down to retain its airy-structure, according to “The Accidental Scientist: Science of Cooking.”

Adding an acid, like lemon juice and cream of tartar, to the eggs makes whipping easier because the acids release hydrogen ions, according to “The Science of Angel Food Cake.”

To keep this cake light, cake flour is the baker’s best choice because it has eight percent protein content, rather than all-purpose flour which has approximately 11 percent. This means it contains less gluten and will be a more tender cake.

Hopefully, understanding the principles of egg whites and cake flour will keep you from creating pancake angel food cakes for your mother’s next birthday.


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