On food and cooking the science and lore of the kitchen ( PDFDrive ) 1515

Ofallthemajorfoodmolecules,proteinsare
themostchallengingandmercurial.The
others,waterandfatsandcarbohydrates,are
prettystableandstaid.Butexposeproteinsto
alittleheat,oracid,orsalt,orair,andtheir
behaviorchangesdrastically.This
changeabilityreflectstheirbiological
mission.Carbohydratesandfatsaremainly
passiveformsofstoredenergy,orstructural
materials.Butproteinsaretheactive
machineryoflife.Theyassembleallthe
moleculesthatmakeacell,themselves
included,andtearthemdownaswell;they
movemoleculesfromoneplaceinthecellto
another;intheformofmusclefibers,they
movewholeanimals.They’reattheheartof
allorganicactivity,growth,andmovement.
Soit’sthenatureofproteinstobeactiveand
sensitive.Whenwecookfoodsthatcontain
them,wetakeadvantageoftheirdynamic
naturetomakenewstructuresand
consistencies.


AminoAcidsandPeptides

Likestarchandcellulose,proteinsarelarge
polymersofsmallermolecularunits.The
smallerunitsarecalledaminoacids.They
consistofbetween10and40atoms,mainly
carbon,hydrogen,andoxygen,withatleast

onenitrogenatominanaminegroup—
NH>2—thatgivestheaminoacidstheir
familyname.Acoupleofaminoacidsinclude
sulfuratoms.Thereareabout20different
kindsofaminoacidsthatoccurinsignificant
quantitiesinfood.Particularprotein
moleculesaredozenstohundredsofamino
acidslong,andoftencontainmanyofthe20
differentkinds.Shortchainsofaminoacids
arecalledpeptides.
Amino Acids and Peptides Contribute
Flavor Three aspects of amino acids are
especiallyimportanttothecook.First,amino
acids participate in the browning reactions