On food and cooking the science and lore of the kitchen ( PDFDrive ) 1179

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%
eachpectinandhemicelluloses).IntheUnited
States, commercial tomato purees may
includeallthewaterintheoriginaltomatoes,
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.
Tomatopasteisthusaconcentratedsourceof
flavor,color,andthickeningpower.(It’salso
aneffectiveemulsionstabilizer;seep.628.)
Thereareseveralvariablesinthe
preparationofpureesthatcanaffecttheir
finaltextureandflavor.Foodscientistshave
shownthismostclearlyformass-produced
tomatopuree.Thegenerallessonsarealso
relevanttothepreparationofpureesfrom
otherfruitsandvegetables.


Tomato Enzymes and Consistency The final
consistency of a tomato puree depends not
just on how much water has been removed,
but also on how long the puree spends at
either moderate or high temperatures. Ripe
tomatoeshaveveryactiveenzymeswhosejob
is to break down pectin and cellulose
molecules in the fruit cell walls, and so give

the fruit its soft, fragile texture. When the
tomatoes are firstcrushed, the enzymes and
their target molecules are thoroughly mixed
together,andtheenzymesstartbreakingdown
the cell-wall structures. If the raw puree is
held at room temperature for a while, or
heated to a temperature below the
denaturation temperature of the pectin
enzymes, around 180ºF/80ºC, then the
enzymeswillbreakdownalotofthecell-wall
reinforcements,andtheseliberatedmolecules
will give a noticeably thicker consistency to
thepuree.
However,whenthepureeisthenheatedto