Colloid emulsion stability

The traditional view of emulsion stability (1,2) was concerned with systems of two isotropic, Newtonian Hquids of which one is dispersed in the other in the form of spherical droplets. The stabilization of such a system was achieved by adsorbed amphiphiles, which modify interfacial properties and to some extent the colloidal forces across a thin Hquid film, after the hydrodynamic conditions of the latter had been taken into consideration. However, a large number of emulsions, in fact, contain more than two phases. The importance of the third phase was recognized early (3) and the lUPAC definition of an emulsion included a third phase (4). With this relation in mind, this article deals with two-phase emulsions as an introduction. These systems are useful in discussing the details of formation and destabilization, because of their relative simplicity. The subsequent treatment focuses on three-phase emulsions, outlining three special cases. The presence of the third phase is shown in order to monitor the properties of the emulsion in a significant manner. 

In the pharmaceutical field, agar is commonly the base colloid for stabilizing mineral oil in water emulsions, used for laxative purposes. The concentration of agar is kept below the gel point, so that the emulsion will pour. Other gums, like tragacanth, Irish moss extract, or carboxymethylcellulose, may replace the agar, where desired. Usually, from 0.5 to 0.8% of the gum, based upon the weight of the aqueous phase, suffices to protect this type of emulsion, which is somewhat of a neutral variety. 

N Garti, A Aserin. Double emulsions stabilized by macromolecular surfactants. Advances in colloid and interfaces science 65 37-69, 1996. 

By using MCT, Leal-Calderon et al. [ 10] measured the total repulsive force between tiny colloidal droplets stabilized with sodium dodecyl sulfate (SDS) (Fig. 2.5). The measurements were performed for emulsions with three different concentrations... 

T.D. Dimitrova, F. Leal-Calderon, T.D. Gurkov, and B. Campbell Surface Forces in Model Oil-in-Water Emulsions Stabilized by Proteins. Adv. Colloid Interface Sci. 108-109, 73 (2004). 

R. Aveyard, B.P. Binks, and J.H. Clint Emulsions Stabilized Solely by Colloidal Particles. Adv. CoUoid Interface Sci. 100-102, 503 (2003). 

A.S. Kabalnov, A.V. Pertsov and E.D. Shchukin Ostwald Ripening in Two-Component Disperse Phase Systems Application to Emulsion Stability. Colloid Surfaces 24, 19 (1987). 

Shinoda K, Aral H (1967) The effect of phase voliune on the phase inversion temperature of emulsions stabilized with nonionic simfacatnts. J Colloid Interface Sci... 

Acevedo S, Gutierrez X, Rivas H (2001) Bitumen-in-water emulsion stabilized with natural surfactants. J Colloid Interface Sci 242 230-238... 

Benichou, A., Aserin, A., Garti, N. (2004). Double emulsions stabilized with hybrids of natural polymers for entrapment and slow release of active matters. Ads ances in Colloid... 

Dickinson, E. (2009). Hydrocolloids as emulsifiers and emulsion stabilizers. Food Hydro-colloids, 23, 1473-1482. 

Dickinson, E., Whyman, R.H., Dalgleish, D.G. (1988). Colloidal properties of model oil-in-water food emulsions stabilized separately by oisi-casein, p-casein and K-casein. In Dickinson, E. (Ed.). Food Emulsions and Foams, London Royal Society of Chemistry, pp. 40-51. 

Mun, S., Decker, E.A., McClements, D.J. (2006). Effect of molecular weight and degree of deacetylation of chitosan on the formation of oil-in-water emulsions stabilized by surfactant-chitosan membranes. Journal of Colloid and Interface Science, 296, 581-590. 

Moschakis, T., Murray, B.S., Dickinson, E. (2005). Microstructural evolution of viscoelastic emulsions stabilized by sodium caseinate and xanthan gum. Journal of Colloid and Interface Science, 284, 714-728. 

Wooster, T.J., Augustin, M.A. (2006). p-Factoglobulin-dextran Maillard conjugates their effect on interfacial thickness and emulsion stability. Journal of Colloid and Interface Science, 303, 564-572. 

Dickinson, E. (2001). Milk protein interfacial layers and the relationship to emulsion stability and rheology. Colloids and Surfaces B Biointerfaces, 20, 197-210. 

A.N. Gurov, M.A. Mukhin, N.A. Larichev, N.V. Lozinskaya and V.B. Tolstoguzov, Emulsifying properties of proteins and polysaccharides, I, Methods of determination of emulsifying capacity and emulsion stability, Colloids Surfaces 6 (1983) 35-42. 

M. H. Kabir, M. Ishitobi, and H. Kunieda, Emulsion stability in sucrose monoalkanoate system with addition of cosurfactants, Colloid Polym. Sci., 280 (2002) 841-847. 

Many food colloids are stabilized from proteins from milk or eggs [817]. Milk and cream, for example, are stabilized by milk proteins, such as casein micelles, which form a membrane around the oil (fat) droplets [817]. Mayonnaise, hollandaise, and bearnaise, for example, are O/W emulsions mainly stabilized by egg-yolk protein, which is a mixture of lipids (including lecithin), proteins, and lipoproteins [811,817]. The protein-covered oil (fat) droplets are stabilized by a combination of electrostatic and steric stabilization [817]. Alcohols may also be added, such as glycerol, propylene glycol, sorbitol, or sucrose sometimes these are modified by esterification or by... 

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