Oil Foams - Definition, Formation and Stabilization Mechanisms, Applications

Liquid foams are systems composed of gas bubbles dispersed in a liquid phase. They can be used in many industries, including the food, cosmetics, and pharmaceutical industries  . There are two main categories: aqueous foams, in which water is the continuous phase, and non-aqueous foams, in which the liquid phase can be any solvent other than water  . For example, the solvent may be an oil, in which case it is referred to as an “oil foam.” Aqueous foams are used in a variety of fields, ranging from cosmetics to food products, as well as in other industrial applications such as mineral flotation, firefighting, and even separation processes in chemical engineering. Liquid foams are thermodynamically unstable systems that tend to separate over time into their individual components: gas and water. The production and stabilization of aqueous foams require the use of foaming and stabilizing agents dispersed in the aqueous phase. Surfactants, polymers, proteins, or particles can be used alone or mixed together to ensure both good foamability and long-term stability. Their role is to extend the foam’s lifespan by slowing down the foam’s aging mechanisms. A major challenge in foam science is indeed controlling the foam’s lifespan (more precisely, optimizing this lifespan for any required application). To achieve this, stabilizing agents must be carefully selected and formulated according to the specific requirements of the intended application. For example, in firefighting foams, the stability and longevity of the foam are crucial for effectively extinguishing fires. In contrast, in food and beverage applications, the foam must not only be stable but also meet sensory standards.

Cosmetic foams are formulations specifically designed to deliver an optimal consumer experience, meeting several key requirements to ensure their effectiveness and appeal. For example, cosmetic foams must feel pleasant to the touch. This quality...