On food and cooking the science and lore of the kitchen ( PDFDrive ) 1503
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— with hydrogen atoms: there are no double
bonds between carbon atoms, so each carbon
within the chain is bonded to two hydrogen
atoms. Anunsaturated lipid has one or more
doublebondsbetweencarbonatomsalongits
backbone. The double-bonded carbons
therefore have only one bond left for a
hydrogen atom. A fat molecule with more
than one double bond is called
polyunsaturated.
Fats and fatty acids. Fatty acids are mainly
chains of carbon atoms, shown here as black
dots. (Each carbon atom has two hydrogen
atomsprojectingfromit;thehydrogenatoms
are not shown.) A fat molecule is a
triglyceride,which is formed from one
moleculeofglycerolandthreefattyacids.The
acidicheadsofthefattyacidsarecappedand
neutralizedbytheglycerol,sothetriglyceride
as a whole no longer has a polar, watercompatible end. The fatty-acid chains can
rotatearoundtheglycerolheadtoformchairlikearrangements(bottom).
FatSaturationandConsistencySaturation
mattersinthebehavioroffatsbecausedouble
bondssignificantlyalterthegeometryandthe
regularityofthefatty-acidchain,andsoits
chemicalandphysicalproperties.Asaturated
fattyacidisveryregularandcanstretchout
completelystraight.Butbecauseadouble
bondbetweencarbonatomsdistortstheusual
bondingangles,ithastheeffectofaddinga
kinktothechain.Twoormorekinkscan
makeitcurl.
Agroupofidenticalandregularmolecules
fitsmoreneatlyandcloselytogetherthan
differentandirregularmolecules.Fats
