On food and cooking the science and lore of the kitchen ( PDFDrive ) 1487
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scratched,andfoodstickstothescratches.
Beginninginthe1980s,flexiblenonstick
sheetsandcontainersmadeofsilicone
havebeenusedbybakerstolinemetal
bakingsheetsorreplacemoldedmetal
pans.Siliconeisalsoalong-chain
molecule,withabackboneofalternating
siliconandoxygenatoms,andsmallfatlikecarbonchainsprojectingfromit.The
backbonegivesthematerialitsflexibility,
andthehydrophobicprojectionsmakethe
surfacebehavelikeapermanentlywelloiledpansurface.Food-gradesilicones
decomposeattemperaturesaboveabout
480ºF/240ºC,solikenonstickpans,
siliconebakewaremustbeusedwithsome
caution.
Copper
Copperisuniqueamongthecommonmetals
becauseitcanbefoundnaturallyinthe
metallicstate.Forthisreasonitwasthefirst
metaltobeusedintoolmaking,about10,000
yearsago.Inthekitchen,itisprizedforits
unmatchedconductivity,whichmakesfast
andevenheatingasimplematter.Butcopper
isalsorelativelyexpensive,sinceits
conductivityhasmadeitthepreferred
materialformillionsofmilesofelectrical
circuitry.Itistroublesometokeeppolished,
becauseithasahighaffinityforoxygenand
sulfur,andformsagreenishcoatingwhen
exposedtoair.Mostimportant,copper
cookwarecanbeharmful.Itsoxidecoatingis
sometimesporousandpowdery,andcopper
ionsareeasilyleachedintofoodsolutions.
Copperionscanhaveusefuleffects:they
stabilizefoamedeggwhites(p.102),andthe
greencolorofcookedvegetablesisimproved
bytheirpresence.Butthehumanbodycan
excretecopperinonlylimitedamounts,and
excessiveintakemaycausegastrointestinal
problemsand,inmoreextremecases,liver
