On food and cooking the science and lore of the kitchen ( PDFDrive ) 1486

neverfoundinnatureinthepurestate,anda
goodmethodforseparatingthemetalfromits
orewasn’tdevelopeduntil1890.Incookware,
itisusuallyalloyedwithsmallamountsof
manganeseandsometimescopper.
Aluminum’sprimeadvantagesareits
relativelylowcost,aheatconductivitysecond
onlytocopper’s,andalowdensitythatmakes
itlightweightandeasilyhandled.Its
ubiquitouspresenceintheformoffoil
wrappingsandbeerandsoftdrinkcans
testifiestoitsusefulness.Butbecause
unanodizedaluminumdevelopsonlyathin
oxidelayer,reactivefoodmolecules—acids,
alkalis,thehydrogensulfideevolvedby
cookedeggs—willeasilypenetratetothe
metalsurface,andavarietyofaluminum
oxideandhydroxidecomplexes,someofthem
grayorblack,areformed.Thesecanmar
light-coloredfoods.Today,mostaluminum
utensilsareeithergivenanonstickcoatingor
areanodized,aprocessthatinvolvesmaking


themetalthepositivepole(anode)ina
solutionofsulfuricacid,andsoforcingthe
oxidationofitssurfacetomakeathick
protectiveoxidelayer.
NonstickCoatingsandSilicone“Pans”
The materials for nonstick coatings were
developed around the middle of the 20th

century by industrial chemists, and
nonstick utensils were introduced in the
1960s. Teflon and its relatives are long
chainsofcarbonatomswithfluorineatoms
projecting from the backbone. They
produce a plastic-like material with a
smooth, slippery surface, and are as inert
as ceramics at moderate cooking
temperatures. Above about 500ºF/250ºC,
however,theydecomposeintoanumberof
noxious and toxic gases. Nonstick utensils
therefore need to be used with care to
avoid overheating. The coatings have the
additional disadvantage of being easily