On food and cooking the science and lore of the kitchen ( PDFDrive ) 556
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medium as water or oil, so air molecules
collide with the food less often, and take
longer to impart energy to it. Second, a cool
object in a hot oven develops a stagnant
“boundary layer” of air molecules and water
vapor that slows the collision rate even
further. (A convection fan speeds cooking by
circulatingtheairmorerapidlyanddisrupting
the boundary layer.) Third, in a dry
atmosphere the food’s moisture evaporates
fromthesurface,andthisevaporationabsorbs
most of the incoming energy, only a fraction
ofwhichgetstothecenter.Sobakingismuch
lessefficientthanboilingorfrying.
Ofcourse,theoven’sthinmediumiswhy
theovenisagoodmeansfordryingfoods,
eitherpartly—forexample,toconcentrate
theflavorofwaterytomatoes—oralmost
fully,topreserveandcreateachewyorcrisp
texture.Andoncethesurfacehasdriedandits
temperaturerisesclosetotheoven’s,then
carbohydratesandproteinscanundergothe
browningreactions,whichgeneratehundreds
ofnewtasteandaromamoleculesandsoa
greaterdepthofflavor.
Oftenvegetablesarecoatedwithoilbefore
baking,andthissimplepretreatmenthastwo
importantconsequences.Thethinsurface
layerofoildoesn’tevaporatethewaythefood
moisturedoes,soalltheheattheoilabsorbs
fromtheovenairgoestoraisingitsandthe
food’stemperature.Thesurfacethereforegets
hotterthanitwouldwithouttheoil,andthe
foodissignificantlyquickerbothtobrown
andtocookthrough.Second,someoftheoil
moleculesparticipateinthesurfacebrowning
reactionsandchangethebalanceofreaction
productsthatareformed;theycreatea
distinctlyricherflavor.
FryingandSautéingBakingoiledvegetables
issometimescalled“ovenfrying,”andindeed
true frying in oil also desiccates the food
surface, browns it, and enriches the flavor
