Question

Which of the following is/are the functions of an emulsifying agent?

• A. It prevents emulsions from splitting or coagulating
• B. It increases the stability of emulsions
• C. An emulsifying agent forms an interfacial film between the dispersed phase and the dispersion medium
• D. An emulsifying agent is soluble in both the dispersion phase and the dispersion medium

Answer 1

Answer: (A), (B), (C), (D)

An emulsifying agent is soluble in both the dispersion phase and the dispersion medium

In most emulsions, the two liquid phases are oil and water and thus emulsions may be of following two types.
(i) Oil-in-water emulsions: In these emulsions, oil is the dispersed phase and water is the dispersion medium. Milk and vanishing cream are the two important examples of this type of emulsion.
(ii) Water-in -oil emulsions: In these emulsions, water is the dispersed phase and oil is the dispersion medium. Butter and cold cream are the common examples.
Emulsions of the first type – oil-in-water tend to be unstable and sometimes separate into two layers on standing. To stabilize such emulsions, we add a third component called the emulsifying agent. The emulsifying agent forms an interfacial film between suspended particles and the medium. In other words, these are substances, which are soluble in both fat and water and enable fat to be uniformly dispersed in water as an emulsion or vice versa. The principal emulsifying agents for oil-in-water emulsions are proteins, gums, and natural and synthetic soaps. For water-in-oil emulsions, long chain alcohols, lampblack, and heavy-metal salts of fatty acids are suitable emulsifying agents.