two incompatible liquids, with droplets of one
liquid dispersed in a continuous phase of the
other, is called an emulsion. The term comes
from the Latin word for “milk,” which is just
such a mixture (p. 17).
Emulsifiers In addition to the two
incompatible liquids, a successful emulsion
requires a third ingredient: an emulsifier. An
emulsifier is a substance of some kind that
coats the oil droplets and prevents them from
coalescing with each other. Several different
materials can serve this function, including
proteins, cell-wall fragments, and a group of
hybrid molecules (for example, egg-yolk
lecithin) that have an oil-like end and a water-
soluble end (p. 802). To make an emulsified
sauce, we add oil to a mixture of water and
emulsifiers (egg yolk, ground herbs or spices),
and break the oil up into microscopic droplets,
which the emulsifiers immediately coat and
stabilize. Or we can begin with a premade