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On food and cooking the science and lore of the kitchen ( PDFDrive ) 1535

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withcan’tsimplychangefromonephaseto
anotherwhenheated.Instead,theyreactto
formentirelydifferentkindsofmolecules.
Thisisbecausefoodmoleculesarelarge,and
formsomanyweakbondsbetweenmolecules
thatthey’reinfactheldverystrongly
together.Ittakesasmuchenergytobreak
themapartfromeachotherasitdoestobreak
themoleculesthemselvesapart:andsorather
thanmeltingorevaporating,themolecules
becometransformed.Forexample,sugarwill
meltfromasolidintoaliquid,butratherthan
thenvaporizeintoagasaswaterdoes,it
breaksapartandformshundredsofnew
compounds:aprocesswecallcaramelization.
Fatsandoilsmelt,butbreakdownandsmoke
beforetheybegintoboil.Starch,whichisa
longchainofsugarmoleculesjoinedtogether,
won’tevenmelt:itandproteins,alsovery
largemolecules,begintobreakdownas
solids.
MixturesofPhases:Solutions,Suspensions,Emulsions,


MixturesofPhases:Solutions,Suspensions,Emulsions,
Gels,Foams

Cooksseldomdealwithpurechemical
compoundsorevensinglephases.Foodsare
mixturesofdifferentmolecules,different
phases,andevendifferentkindsofmixtures!


Herearebriefdefinitionsofmixturesthatare
importantinthekitchen.
Asolutionisamaterialinwhich
individualionsormoleculesare
dispersedinaliquid.Saltbrinesand
sugarsyrupsaresimpleculinary
examples.
Asuspensionisamaterialinwhicha
substanceisdispersedinaliquidin
clustersorparticlesconsistingofmany
molecules.Nonfatmilkisasuspension
ofmilk-proteinparticlesinwater.
Suspensionsareusuallycloudybecause
theclustersarelargeenoughtodeflect
lightrays(individualdissolved



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