On Food and Cooking

Some of the most delicious sauces we eat,
including tomato sauces and applesauce, are
made simply by crushing fruits and
vegetables. Crushing, or pureeing, frees the
juices from the cells of the fruit or vegetable,
and breaks the cell walls into fragments that
become suspended in the juices and block
their flow, so giving them some thickness.
Crushed nuts and spices have no juices of
their own, but they thicken a liquid to which
they’re added by absorbing some of its water
and providing dry cell particles that obstruct
the liquid’s flow.
Until recently, most purees of plant tissue
would have been made by cooking the tissue
to soften it, and then either grinding it in a
mortar or forcing it through a fine sieve. Raw
purees could only be made from fruits
softened by ripening, or from brittle nuts.
Today’s cooks can use powerful machines —
blenders, food processors — to puree any fruit
or vegetable or seed with ease, whether