On food and cooking the science and lore of the kitchen ( PDFDrive ) 1500

LipidsDon’tMixwithWater

Fatsandoilsaremembersofalargechemical
familycalledthelipids,atermthatcomes
fromtheGreekfor“fat.”Fatsandoilsare
invaluableinthekitchen:theyprovideflavor
andapleasurableandpersistentsmoothness;
theytenderizemanyfoodsbypermeatingand
weakeningtheirstructure;they’reacooking
mediumthatallowsustoheatfoodswell
abovetheboilingpointofwater,thusdrying
outthefoodsurfacetoproduceacrisptexture
andrichflavor.Manyofthesequalitiesreflect
abasicpropertyofthelipids:theyare
chemicallyunlikewater,andlargely
incompatiblewithit.Andthankstothis
quality,theyhaveplayedanessentialrolein
thefunctionofalllivingcellsfromthevery
beginningsoflife.Becausetheydon’tmix
withwater,lipidsarewellsuitedtothejobof
formingboundaries—membranes—
betweenwaterycells.Thisfunctionis


performedmainlybyphospholipidssimilarto
lecithin(p.802),moleculesthatcooksalso
usetoformmembranesaroundtinyoil
droplets.Fatsandoilsthemselvesarecreated
andstoredbyanimalsandplantsasa
concentrated,compactformofchemical
energy,packingtwicethecaloriesasthesame

weightofeithersugarorstarch.
Inadditiontofats,oils,andphospholipids,
thelipidfamilyincludesbetacaroteneand
similarplantpigments,vitaminE,cholesterol,
andwaxes.Theseareallmoleculesmadeby
livingthingsthatconsistmainlyofchainsof
carbonatoms,withhydrogenatomsprojecting
fromthechain.Eachcarbonatomcanform
fourbondswithotheratoms,soagiven
carbonatominthechainisusuallybondedto
twocarbonatoms,oneoneachside,andtwo
hydrogens.
Thiscarbon-chainstructurehasone
overridingconsequence:lipidscan’tdissolve
inwater.Theyare“hydrophobic”or“water-