Abstract
Today, naturally occurring foam constituents and surface-active proteins with intriguing structures and functions are being identified from a variety of biological and chemical sources. In this paper we studied the colloid chemical properties of high-molecular natural surfactants such as keratin hydrolyzate (1.5–15%), gelatin (0.1–1%), and egg albumin (0.1–1%) in a wide concentration range. The foaming ability and foam-stabilizing properties of mixtures of these proteins were established. The high stability of foams obtained from mixtures of surfactants can be explained by the formation of mixed structured layers from the surface-active associates, promoting the thickening of foam films. The ratio of polymer mixtures was optimized (keratin (15%)-albumin (1%) (1:1)) to produce high-quality foaming agents. The foam parameters such as surface tension, capillary pressure of the Plateau-Gibbs channels, radii of curvature, critical micelle concentration, and relative viscosity were defined. The high surface activity and foam stability corresponds to a pH close to the isoelectric state of the proteins. This occurs due to the conformational changes of macromolecules of the protein at the liquid-gas interface, forming particles of colloidal size.