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What is Solid Foam?
Foam is often associated with a light fluffy substance that is airy and smooth in texture. However, there are times when culinary foam takes on a concrete form.
Gas dispersed in a solid continuous phase produces a preparation known as solid foams. While it may not seem common, solid foams are actually encountered everyday in various forms. The most common types of solid foams to be found around include breads and cakes.
Certain types of cakes such as sponge, chiffon, angel cake and meringue form foam by whipping egg whites and then adding it to the other ingredients. However, the process of trapping a gas within a solid material can also happen with the help of a leavening agent such as yeast, baking powder and baking soda. All of these produce a chemical reaction when mixed with other specific ingredients. As a result carbon dioxide is released within the solids, causing these to foam and rise.
Solid foams such as breads are usually made by diluting yeast in lukewarm water to activate the microorganisms. A live culture may also be used from a previously made sample. These are then mixed with other ingredients and the yeast releases gas throughout the process.