On Food and Cooking

fluids and breaking the cell walls and other
structures into small particles. A puree is a
mixture of plant particles and molecules
floating in water (left). If left to stand, most
purees will separate, with the larger particles
settling to the bottom (center). This separation
can be prevented, and the puree consistency
thickened, by cooking the puree down and
evaporating the excess water (right).
Preventing Separation The consistency of a
puree is also improved by reducing the
amount of water in the continuous phase. The
simplest way to do this is to cook the whole
puree down, simmering gently, until the
separate thin phase disappears. Another way
that better preserves the puree’s fresh flavor is
to drain the thin fluid off the solids and either
discard it, or cook it down separately and then
add it back. Or the cook can remove some of
the fruit’s or vegetable’s water before
crushing it, for example by partly drying
halved tomatoes in the oven.