Protein‐stabilized foams and emulsions

Abstract

This review is a survey of studies on protein-stabilized foams and emulsions in relatively simple, well-defined systems (rather than in food products per se). The emphasis is on the extent of basic understanding developed, particularly in terms of the physicochemical properties involved. The stability of the system, its formation, and its rheology are covered. Unfortunately, much work is of limited fundamental value because of poorly designed experimental approaches and the failure to measure key parameters. Reasonable generalization can be made concerning the effects of a number of variables, particularly protein solubility, pH, protein structure and the presence of small molecule surfactants. However, several possible explanations of these effects in terms of surface properties remain tenable. A number of observations can fairly confidently be ascribed to the influence of rheology on flow processes within foams and emulsions.

Chemical composition, molecular weight distribution, secondary structure and effect of NaCl on functional properties of walnut (Juglans regia L) protein isolates and concentrates

“…Meanwhile, this may be attributed to the fact that addition of sodium chloride, at a concentration up to 0.6 M, enhances the protein solubility by weakening the hydrophobic interaction of the protein while high salt concentration had an adverse effect on FC due to the salting effect of sodium chloride. To exhibit good foaming, a protein must be capable of migrating at the airwater interface, unfolding and rearranging at the interface (Hailing and Walstra 1981). The foam capacity and stability were enhanced by greater protein concentration, because this increases the viscosity and facilitates the formation of a multilayer, cohesive protein film at the interface (Damodaran 1997).…”

Albumen protein and functional properties of gelation and foaming

“…The strength magnitude, which keeps the native protein structure either in solution or at the interface, is important in the foaming properties (Adamson, 1982). Barmore (1934) apud Halling (1981), showed the stability decrease of foam in the super-beating of the eggwhite, and the drainage increase correlated to the decrease of viscosity of the liquid drained off.…”

“…The viscosity decrease does not sufficiently explain the increase in the drainage rate in long periods of eggwhite beating. Conceivably a specific protein component also performs an important role in the eggwhite super-beating (Halling, 1981).…”

Application Potential of Food Protein Modification

“…The stability of the air bubbles in a foam is determined by the foaming agent which forms a layer of adsorbed molecules separating the air bubbles from the continuous liquid phase, similar to the emulsifying activity described in paragraph 2.1.1 (reviewed in Halling, 1981;Wilde, 2000). Adsorption of a protein to the air-water interface induces partial dehydration of the molecule promoting protein-protein interactions.…”