Foam (cooking)

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Foam in cooking is a light, airy mixture where air is trapped inside a gel or liquid. It has water-based liquid with air bubbles and examples like whipped cream, meringue, and mousse. By beating or whisking, air is added, making the food lighter and giving a different mouthfeel. Foams let cooks add flavor without adding much weight.

In modern kitchens, foams are used in molecular gastronomy. Flavors such as fruit juices or herbal infusions are mixed with a neutral stabilizer like lecithin or agar, then aerated with a hand blender or dispensed from a canister with nitrous oxide to create foam. Common examples include foamed espresso, foamed mushroom, foamed beet, and foamed coconut. An espuma or thermo whip is often used to make these foams from a stock or liquid base.

Stability comes from surfactants—substances that sit at the air–liquid surface and lower the surface tension. This helps bubbles form and stay intact. Small surfactants like lecithin or monoglycerides are often very effective; proteins can help too, especially when heated, such as soy or whey proteins.

Foams appear in many foods, including whipped cream, ice cream, cakes, meringue, soufflés, mousse, and marshmallows. They feel light because of the tiny air bubbles. A special, very fine foam called microfoam is common in coffee drinks like lattes.

Foam stability is about how long the foam keeps its structure. A typical measure is the time it takes for half of the liquid to drain away from the foam.