On Food and Cooking

size of its particles. The smaller the particles,
the less noticeable they are to the tongue, and
the smoother the texture. Also, the smaller the
particles are, the more of them there are to do
the obstructing and the more surface area they
have to take up a layer of water molecules:
and so the thicker the consistency they
produce. Suspensions are always opaque,
because the solid particles are large enough to
block the passage of light rays and either
absorb them or bounce them back toward their
source. Because the particles and water are
very different materials, suspensions tend to
settle and separate into thin fluid and
concentrated particles. Cooks work to prevent
separation by reducing the volume of the
continuous phase (draining off or boiling
away excess water), or by augmenting the
dispersed phase (adding starch or other long
molecules or fat droplets).
Nut butters and chocolate are suspensions
of solid seed particles not in water, but in oils