Micelles dressed

Most food products and food preparations are colloids. They are typically multicomponent and multiphase systems consisting of colloidal species of different kinds, shapes, and sizes and different phases. Ice cream, for example, is a combination of emulsions, foams, particles, and gels since it consists of a frozen aqueous phase containing fat droplets, ice crystals, and very small air pockets (microvoids). Salad dressing, special sauce, and the like are complicated emulsions and may contain small surfactant clusters known as micelles (Chapter 8). The dimensions of the particles in these entities usually cover a rather broad spectrum, ranging from nanometers (typical micellar units) to micrometers (emulsion droplets) or millimeters (foams). Food products may also contain macromolecules (such as proteins) and gels formed from other food particles aggregated by adsorbed protein molecules. The texture (how a food feels to touch or in the mouth) depends on the structure of the food. 

Liquid soap helps to reduce surface tension (Box 25.1) and therefore improves the penetration of active agents. It also improves maceration under an occlusive dressing. Anionic and cationic soaps, like alcohol, enhance the action of phe-nol. " Formulation requirements are strict. If there is too much surfactant, the phenol ends up within a micelle and its action is reduced. If there is not enough, the solutions are not stable. 

Hayter, J. B. A self-consistent theory of dressed micelles. Langmuir 1992 8 2873-2876. 

K. Taiwo, H. Karbstein, and H. Schubert [/. Food Process Eng., 20, 1-16 (1997)] studied the influence of temperature on the kinetics of adsorption of a variety of food emulsifiers at oil-water interfaces. They used interfacial tension measurements to monitor the rate at which egg yolk present at 10 times its critical micelle concentration was transferred to a water-soybean oil interface. The rates of these processes are important in assessing the potential stability of oil-in-water emulsions of the type found in salad dressings and mayonnaise. The interfacial tension can be viewed as a property that reflects the contributions of the various species present at the interface, being an additive function of these contributions. Each individual contribution is proportional to the quantity of the material in question located at the interface between the oil and the water. The reaction of interest can be regarded as... 

The first term on the right-hand side of equation (8.7) is the contribution of the head group repulsion, while the second is the interfacial energy contribution where Ahg is the total surface area of the head groups and (Tmic is the interfacial tension. Within the framework of the Gouy-Chapmann theory, the dressed micelle model allows the estimation of values, which are for sodium dodecyl sulfate (SDS), sodium octyl sulfate, and teradecyltrimethylammonium bromide, 15-16, 11 and 11-14 mN m , respectively (15). Note that these values are up to a factor of 3 lower than those of the pure monomers (cf. Table 8.2). A further decrease of or is possible in the case of emulsions of organic liquids where the interface is saturated with stabilizer. For example, a value of about 4 mN m was determined for a toluene emulsion stabilized with potassium lau-rate (16). 

Refinements in considering separately the sub-volumes as the palisade layer and the core have allowed a unique example of predicting solubilization in the case of charged w/o systems when electrostatic effects are explicitly taken into account as the dressed model of micelles (27). This example is the only work to our knowledge for which the whole phase diagram has been explicitly calculated from osmotic pressure and free energy equilibria in co-existing phases. 

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