On Food and Cooking

the water molecules then heat up the cell wall,
starch, and other plant molecules (p. 786).
Because radiation penetrates into food an
inch/2 cm or so, it can be a fairly rapid
method, and is an excellent one for retaining
vitamins and minerals. However, it has
several quirks that the cook must anticipate
and compensate for. Because the microwaves
penetrate a limited distance into the food, they
will cook evenly only if the food is cut into
similar-sized thin pieces, and the pieces
arranged in a single layer or very loose pile.
Energetic water molecules turn into water
vapor and escape from the food: so
microwaves tend to dry foods out. Vegetables
should be enclosed in an almost steam-tight
container, and often benefit from starting out
with a small amount of added water so that
their surfaces don’t lose too much moisture
and shrivel. And because the foods must be
enclosed, they retain some volatile chemicals
that would otherwise escape — so their flavor