Foam (culinary) - Creating Culinary Foam

Creating Culinary Foam

To form a stable foam and emulsion, a surfactant, such as lecithin, monoglycerides or proteins, must be present to reduce the interfacial tension 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.

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: whipped cream, ice cream, cakes, meringue, bread, soufflés, mousse and marshmallow. It has a unique light texture because of the tiny air bubbles and/or a different mouth feel. 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.

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 over come, such as gravitational and mechanical, it’s the proteins ability to stabilize foam against these stresses that determines the foams stability. The foams stability is usually expressed as the time required for 50% of the liquid to drain from foam (a 50% reduction in foam volume).