ancient,someaproductoftheindustrialage.
Dryingand
Freeze-Drying

DryingDryingpreservesfoodsbyreducing
thetissue’swatercontentfromaround90%to
between5and35%,arangeinwhichvery
littlecangrowonit.Thisisoneoftheoldest
preservativetechniques;thesun,fire,and
moundsofhotsandhavebeenusedtodry
foodssinceprehistory.Fruitsandvegetables
usuallybenefitfromtreatmentstoinactivate
theenzymesthatcausevitaminandcolor
damage.Commerciallydriedvegetablesare
usuallyblanched;andfruitsaredippedor
sprayedwithanumberofsulfurcompounds
thatpreventoxidationandtherebyenzymatic
browningandthelossofantioxidantphenolic
compounds,vitamins,andflavor.Whilesundryingusedtobethemostcommontreatment
forprunes,raisins,apricots,andfigs,forced


hotair-dryingisnowwidelyusedbecauseitis
morepredictable.Homeandrestaurantcooks
canusetheovenorsmallelectricdriers
whosetemperatureiseasiertocontrol.Fruits
andvegetablesaredriedatrelativelylow
temperatures,130–160ºF/55–70ºC,to
minimizethelossofflavorandcolorand
preventthesurfacefromdryingtoofastand
impedingmoisturelossfromwithin.Pureed

fruitsarespreadoutintothinsheetstomake
“fruitleather.”Relativelymoistdriedfruits
andvegetablesarenicelysoft,butthey’realso
vulnerabletosomehardyyeastsandmolds,
andthereforearebeststoredinthe
refrigerator.
Freeze-Drying Freeze-drying is a controlled
version of freezer burn: it removes moisture
not by evaporation but by sublimation, the
transformation of ice directly into water
vapor.Although we think of freeze-drying as
a recent industrial innovation, the natives of