Updated: Aug 27, 2019
Scroll to the bottom of this post to see the recipes.
Foams are fun, and they are used more often in cooking than you may realize. A foam is when a gas is dispersed into a liquid. Foams fall under the category of dispersions, or an "evenly-spread mix of one material into another". The main component that makes foams is the interaction between water and air. There are several different types of foams: egg foams, fat foams, gluten foams, gelatin foams, and sugar foams. But they all involve the same important chemical component: proteins.
In most foams, proteins are denatured, or changed from their original state. The building blocks that make them, amino acids, can either be attracted to water, or attracted to oils and fats.
Proteins are large combinations of strands and sheets of amino acids, tangled up in shapes important to their functions. When these proteins are whipped or heated, they unfold, and denature. As the proteins unfold, they interact with oils and fats, as well as the air. The water-loving ends of the proteins stay in the water, and the fat-loving parts stick into the fats or air, avoiding the water. As the proteins are beaten, the bubbles formed get smaller and smaller and are covered by a protein film. The proteins link together and form a tough film, preventing the bubbles from merging together again. These pockets of air are what create the stiff peaks that make whipped cream, marshmallows, and meringues thick and delicious.
Culinary Reactions, which can be purchased here
Cocktail Science from Serious Eats
The Pizza Lab from Serious Eats
Now that you know more about foams, here are some recipes that include them:
Genius Kitchen's Cloud Bread
Alton Brown's Homemade Marshmallows