Peru have been freeze-drying potatoes in the
Andes for millennia. To make chuño, which
can be stored indefinitely, they trample
potatoes to break down their structure and
expose them constantly to the dry, cold
mountain air, so that they freeze at night and
lose some moisture by sublimation, then thaw
during the day and lose more water by
evaporation. Chuño develops a strong flavor
from the disruption of the potato tissues and
long exposure to the air and sun, and is
reconstituted in water to make stews.
In modern industrial freeze-drying, foods
are quickly chilled to as low as –70ºF/–57ºC,
then slightly warmed and subjected to a
vacuum, which pulls their water molecules
out and dries them. Because the foods aren’t
heated or exposed to oxygen, their flavor and
color remain relatively fresh. Many fruits and
vegetables are freeze-dried today and used as
is for snack foods, or reconstituted with water
in instant soup mixes, emergency rations, and
barry
(Barry)
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