On Food and Cooking

the world, is tomato sauce and paste. The
solids in tomatoes are about two-thirds
flavorful sugars and organic acids, and 20%
cell-wall carbohydrates that have some
thickening power (10% cellulose, and 5%
each pectin and hemicelluloses). In the United
States, commercial tomato purees may
include all the water in the original tomatoes,
or just a third. Tomato paste is tomato puree
cooked down so that it contains less than a
fifth of the water of the raw vegetable.
Tomato paste is thus a concentrated source of
flavor, color, and thickening power. (It’s also
an effective emulsion stabilizer; see p. 628.)
There are several variables in the
preparation of purees that can affect their
final texture and flavor. Food scientists have
shown this most clearly for mass-produced
tomato puree. The general lessons are also
relevant to the preparation of purees from
other fruits and vegetables.