ancient, some a product of the industrial age.
Drying and
Freeze-Drying
Drying Drying preserves foods by reducing
the tissue’s water content from around 90% to
between 5 and 35%, a range in which very
little can grow on it. This is one of the oldest
preservative techniques; the sun, fire, and
mounds of hot sand have been used to dry
foods since prehistory. Fruits and vegetables
usually benefit from treatments to inactivate
the enzymes that cause vitamin and color
damage. Commercially dried vegetables are
usually blanched; and fruits are dipped or
sprayed with a number of sulfur compounds
that prevent oxidation and thereby enzymatic
browning and the loss of antioxidant phenolic
compounds, vitamins, and flavor. While sun-
drying used to be the most common treatment
for prunes, raisins, apricots, and figs, forced