On food and cooking the science and lore of the kitchen ( PDFDrive ) 323

gently. Water at a 180ºF/80ºC simmer in a
covered pot will keep the pot atmosphere
around 180º as well, and leave the outer
portions of the meat less overdone. In China,
some dishes are steamed in open pots, where
the water vapor mixes with ambient air and
the temperature is well below the boil.
Commercialconvectionsteamerscanproduce
saturated vapor all the way from body
temperaturetotheboil.Theymakeitpossible
for restaurant cooks to prepare moist meats
and fish with very little attention and keep
thematservingtemperatureuntilneeded.
High-Pressure and Low-Pressure Cooking
While conventional cooking is limited to an
effectivemaximumtemperatureoftheboiling
point of water (p. 784), the pressure cooker
allowsustoraisethatmaximumfrom212to
250ºF/100 to 120ºC. It does so by tightly
sealingthemeatandcookingliquidinthepan
andallowingthevaporizingwatertobuildup


the pressure to about double the normal air
pressure at sea level. This increased pressure
increasestheboilingpoint,andhighpressure
and temperature put together produce an
overall doubling or tripling of the heat
transfer rate into the meat, as well as an
extremely efficient conversion of collagen
into gelatin. Pot roasts cook in less than an

hour instead of two or three. Of course the
proteins get very hot and therefore squeeze
outmuchoftheirmoisture;meatmustbewell
endowed with fat and collagen to end up
anythingbutdry.
Attheotherendofthepressurescaleis
cookingathighaltitude,wherethe
atmosphericpressureissignificantlylower
thanitisatsealevel.Theboilingpointof
waterisalsolower(203ºF/95ºCatmile-high
Denver,194ºF/90ºCat10,000feet/3,000
meters),andmeatcookingmoregentle—and
moretime-consuming.
MicrowaveCooking