On food and cooking the science and lore of the kitchen ( PDFDrive ) 1508
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moleculesarecapableofformingsomany
bondsalongtheirlengthyhydrocarbonchains,
theindividuallyweakinteractionshavea
largeneteffect:ittakesalotofheatenergyto
knockthemoleculesapartfromeachother.
Omega-3fattyacids.Omega-3fattyacidsare
unsaturated fatty acids whose first double
bondbeginsatthethirdcarbonatomfromthe
end. (The most common unsaturated fatty
acids are omega-6 fatty acids.) They are
essential in our diet for, among other things,
the proper function of the immune and
cardiovascular systems. Linolenic acid has 3
doublebondsamongits18carbonatoms,and
isfoundingreenleavesandinsomeseedoils.
Eicosapentaenoic acid has 20 carbons and 5
doublebonds,andisfoundalmostexclusively
inseafood(p.183).
TheSmokePointMostfatsbeginto
decomposeattemperatureswellbelowtheir
boilingpoints,andmayevenspontaneously
igniteonthestovetopiftheirfumescomeinto
contactwiththegasflame.Thesefactslimit
themaximumusefultemperatureofcooking
fats.Thecharacteristictemperatureatwhicha
fatbreaksdownintovisiblegaseousproducts
iscalledthesmokepoint.Notonlyarethe
smokyfumesobnoxious,buttheother
materialsthatremainintheliquid,including
chemicallyactivefreefattyacids,tendtoruin
theflavorofthefoodbeingcooked.
Thesmokepointdependsontheinitialfree
fattyacidcontentofthefat:thelowerthefree
fattyacidcontent,themorestablethefat,and
thehigherthesmokepoint.Freefattyacid
levelsaregenerallylowerinvegetableoils
thaninanimalfats,lowerinrefinedoilsthan
unrefinedones,andlowerinfreshfatsand
oilsthaninoldones.Freshrefinedvegetable
oilsbegintosmokearound450ºF/230ºC,
