On food and cooking the science and lore of the kitchen ( PDFDrive ) 1501
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fearing”substances.Thereasonforthisisthat
carbonandhydrogenatomspullwithasimilar
forceontheirsharedelectrons.Sounlikethe
oxygen-hydrogenbond,thecarbon-hydrogen
bondisnotpolar,andthehydrocarbonchain
asawholeisnonpolar.Whenpolarwaterand
nonpolarlipidsaremixedtogether,thepolar
watermoleculesformhydrogenbondswith
eachother,thelonglipidchainsforma
weakerkindofbondwitheachother(vander
Waalsbonds,p.814),andthetwosubstances
segregatethemselves.Oilsminimizethe
surfaceatwhichtheycontactwaterby
coalescingintolargeblobs,andresistbeing
dividedintosmallerdroplets.
Thankstotheirchemicalrelatedness,
differentlipidscandissolveineachother.
Thisiswhythecarotenoidpigments—the
betacaroteneincarrots,thelycopenein
tomatoes—andintactchlorophyll,whose
moleculehasalipidtail,colorcookingfats
muchmoreintenselythantheydocooking
water.
Lipidssharetwoothercharacteristics.One
istheirclingy,viscous,oilyconsistency,
whichresultsfromthemanyweakbonds
formedbetweentheirlongcarbon-hydrogen
molecules.Andthosesamemoleculesareso
bulkythatallnaturalfats,solidorliquid,float
onwater.Waterisadensersubstancedueto
itsextensivehydrogenbonding,whichpacks
itssmallmoleculesmoretightlytogether.
TheStructureofFats
Fatsandoilsaremembersofthesameclassof
chemicalcompounds,thetriglycerides.They
differfromeachotheronlyintheirmelting
points:oilsareliquidatroomtemperature,
fatssolid.Ratherthanusethetechnical
triglyceridetodenotethesecompounds,I’ll
usefatsasthegenericterm.Oilsareliquid
fats.Theseareinvaluableingredientsin
cooking.Theirclingyviscosityprovidesa
