On Food and Cooking

liquid, and give emulsions their
characteristically milky appearance.
The more droplets that are crowded into
the continuous phase, the more they get in the
water’s and each other’s way, and the more
viscous the emulsion is. In light cream, the fat
droplets take up about 20% of the total
volume and water 80%; in heavy cream, the
droplets are about 40% of the volume; and in
stiff, semisolid mayonnaise, oil droplets
occupy nearly 80% of the volume. If the cook
works more of the dispersed liquid into the
emulsion, then it gets thicker; if he adds more
of the continuous liquid, then there’s more
space between droplets, and the emulsion
becomes thinner. Clearly it’s important to
keep in mind which phase is which.
Because nearly all emulsified sauces are
oil-in-water systems, I’ll assume in most of
the following discussion that the continuous
phase is water, the dispersed phase oil.