In cuisine, foam is a gelled or stabilized liquid in which air is suspended. Foams have been present in many forms over the history of cooking, such as

whipped cream Whipped cream, also known as Chantilly cream or (), is high-fat dairy cream that has been aerated by whisking until it becomes light, fluffy, and capable of holding its shape. This process incorporates air into the cream, creating a semi-soli ...

meringue Meringue ( , ) is a type of dessert or candy, of French cuisine, French origin, traditionally made from Whisk, whipped egg whites and sugar, and occasionally an acid, acidic ingredient such as lemon, vinegar, or potassium bitartrate, cream of t ...

and

mousse A mousse (, ; ) is a soft prepared food that incorporates air bubbles to give it a light and airy texture. Depending on preparation techniques, it can range from light and fluffy to creamy and thick. A mousse may be sweet or savory. as early ...

. In these cases, the incorporation of air, or another gas, creates a lighter texture and a different

mouthfeel Mouthfeel refers to the physical sensations in the mouth caused by food or drink, making it distinct from taste. It is a fundamental sensory attribute which, along with taste and smell, determines the overall flavor of a food item. Mouthfeel i ...

. Foams add flavor without significant substance, and thus allow cooks to integrate new flavors without changing the physical composition of a dish. More recently, foams have become a part of

molecular gastronomy Molecular gastronomy is the Science, scientific approach of cuisine from primarily the perspective of chemistry. The composition (Structural formula, molecular structure), properties (mass, viscosity, etc) and transformations (chemical reaction ...

technique. In these cases, natural flavors (such as fruit juices, infusions of aromatic herbs, etc.) are mixed with a neutrally-flavored gelling or stabilizing agent such as

agar Agar ( or ), or agar-agar, is a jelly-like substance consisting of polysaccharides obtained from the cell walls of some species of red algae, primarily from " ogonori" and " tengusa". As found in nature, agar is a mixture of two components, t ...

lecithin Lecithin ( ; from the Ancient Greek "yolk") is a generic term to designate any group of yellow-brownish fatty substances occurring in animal and plant tissues which are amphiphilic – they attract both water and fatty substances (and so ar ...

, and either whipped with a hand-held immersion blender or extruded through a whipped cream canister equipped with

nitrous oxide Nitrous oxide (dinitrogen oxide or dinitrogen monoxide), commonly known as laughing gas, nitrous, or factitious air, among others, is a chemical compound, an Nitrogen oxide, oxide of nitrogen with the Chemical formula, formula . At room te ...

cartridges. Some famous food-foams are foamed espresso, foamed mushroom, foamed beet and foamed coconut. An espuma or thermo whip is commonly used to make these foams through the making of a stock, creating a gel and extruding through the nitrous oxide canister.

Creating culinary foam

To form a stable foam and

emulsion An emulsion is a mixture of two or more liquids that are normally Miscibility, immiscible (unmixable or unblendable) owing to liquid-liquid phase separation. Emulsions are part of a more general class of two-phase systems of matter called colloi ...

, a

surfactant Surfactants are chemical compounds that decrease the surface tension or interfacial tension between two liquids, a liquid and a gas, or a liquid and a solid. The word ''surfactant'' is a Blend word, blend of "surface-active agent", coined in ...

, such as

monoglyceride Monoglycerides (also: acylglycerols or monoacylglycerols) are a class of glycerides which are composed of a molecule of glycerol linked to a fatty acid via an ester bond. As glycerol contains both primary and secondary alcohol groups two differe ...

s or

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

s, must be present to reduce the

interfacial tension Surface tension is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible. Surface tension is what allows objects with a higher density than water such as razor blades and insects (e.g. water striders) to ...

between the air-oil phase and the aqueous phase. If the surfactants are at equal concentrations at the interface, proteins are generally less effective than small surfactants, such as lecithin or monoglycerides, at decreasing the interfacial tension. Of course, this is not true of heated soybean or whey protein, which readily forms copious foam. Foams consist of two phases, an aqueous phase and a gaseous (air) phase. Foams have been used in many forms in the history of cooking, for example:

ice cream Ice cream is a frozen dessert typically made from milk or cream that has been flavoured with a sweetener, either sugar or an alternative, and a spice, such as Chocolate, cocoa or vanilla, or with fruit, such as strawberries or peaches. Food ...

cake Cake is a flour confection usually made from flour, sugar, and other ingredients and is usually baked. In their oldest forms, cakes were modifications of bread, but cakes now cover a wide range of preparations that can be simple or elabor ...

soufflé A soufflé () is a baked egg dish originating in France in the early 18th century. Combined with various other ingredients, it can be served as a savoury main dish or sweetened as a dessert. The word ''soufflé'' is the past participle of the Fr ...

and

marshmallow Marshmallow (, ) is a confectionery made from sugar, water and gelatin whipped to a solid-but-soft consistency. It is used as a filling in baking or molded into shapes and coated with corn starch. This sugar confection is inspired by a medicina ...

. It has a unique light texture because of the tiny air bubbles and/or a different

. In most of these products, proteins are the main surface active agents that help in the formation and stabilization of the dispersed gas phase. To create a protein-stabilized foam, it usually involves bubbling, whipping or shaking a protein solution and its foaming properties refers to its capacity to form a thin tenacious film at the gas-liquid interface for large amounts of gas bubbles to become incorporated and stabilized.

Microfoam Microfoam is finely textured milk used for making espresso-based coffee drinks, particularly those with latte art. It is typically made with the steam wand of an espresso machine, which pumps steam into a pitcher of milk. The opposite of microfo ...

is a particularly fine type of milk foam used in

latte Latte () or caffè latte (), also known as , or , is a List of coffee drinks, coffee drink of Italian cuisine, Italian origin made with espresso and steamed milk, traditionally served in a glass. Variants include the chocolate-flavored ''caf ...

s and related coffee drinks. When protein concentrations are increased to their maximum value the foaming powers and foam formation are generally increased. Often to compare foaming properties of various proteins, the foaming power at a specific protein concentration is determined. A protein will always have certain stresses that it must overcome, such as gravitational and mechanical; it is the protein's ability to stabilize foam against these stresses that determines the foam's stability. The foam's stability is usually expressed as the time required for 50% of the liquid to drain from foam (a 50% reduction in foam volume).

References

{{reflist Cooking techniques Molecular gastronomy Culinary terminology