ABSTRACT
Butter, cream, ice cream, milk, mayonnaise, and salad dressing are rep re sentative o f food products that contain both water and fat in the form of emulsions. Some form ulated m eat products have from time to time been re ferred to as emulsions, but are m ore properly excluded for this classification. Some true emulsions tend to be solid or semi-solid and are quite d ifferen t from products that are liquid. Such solid emulsions will not be discussed in this chapter. Fluid emulsions are therm odynamically unstable m ixtures o f immiscible liquids such as vegetable oil and water. T heir form ation requires the application o f energy. W hen energy is applied to a m ixture o f water and oil, the phases may be dispersed, but increased surface energy causes rapid coalescence unless an energy barrier is established. A molecule that contains a moiety that is soluble in water and another that is soluble in nonpolar solvents is term ed am phiphilic. Immiscible liquids may be stabilized against coalescence by the
addition o f these types o f molecules, generally re ferred to as emulsifiers. Proteins are capable o f coating lipid droplets and can provide an energy barrier to both particle association and phase separation. T he num ber o f com ponent interactions possible makes the study o f emulsion systems complex.
