Aeration of emulsions by whipping

During aeration of food emulsions such as dairy cream and ice cream, small gas bubbles are introduced, which are often stabilized by a layer of adsorbed emulsion droplets. It is shown that the maximum achievable volume of gas bubbles that can be incorporated by whipping depends on the effectiveness of the introduction of gas during the first stage of whipping and is furthermore limited by packing constraints. The main factors relevant for the latter limitation are the thickness of the coating of emulsion droplets at the bubble surface, the ratio between the droplet and bubble radii, and the fat content of the emulsion. It is hypothesized that, during whipping, a dynamic process of bubble break-up and coalescence adjusts the average bubble size and the volume of gas incorporated in the foam to the constraint of close packing of the bubbles. The consequences of this mechanism for whipping of emulsions are discussed.