On food and cooking the science and lore of the kitchen ( PDFDrive ) 1289
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temperature.Therapidlymovingwater
moleculesinahotsugarsolutioncankeep
moresugarmoleculesdissolvedthanthe
sluggishwatermoleculesinacoldsolution
can.Themomentthatahotandsaturated
solutionbeginstocool,itbecomessuper
saturated.Thatis,ittemporarilycontains
moredissolvedsugarthanitnormallycouldat
thattemperature.Andoncethesolutionhas
becomesupersaturated,thesmallest
disturbancewillinducesugarcrystalstoform
andgrow.Asthesugarmoleculesgatherinto
solidcrystals,theyleavethesolutionaround
themlessconcentrated.Whenthesolution
reachesthesugarconcentrationappropriate
foritsnewtemperature,thesugarcrystals
stopformingandgrowing.Thesugarisnow
intwodifferentstates:someremains
dissolvedinthesyrup,andsomeispackedin
thesolidcrystalssurroundedbythesyrup.
Therearetwostepsinsugar
crystallization:theformationofcrystal
“seeds,”andthegrowthofthoseseedsinto
mature,full-sizedcrystals.Seedformation
determineshowmanycrystalswillform,and
crystalgrowthdetermineshowlargetheyget.
Bothstepsaffectthefinaltextureofacandy.
The growth of sugar crystals as a hot syrup
cools. Left:Crystals are tightly organized,
solid clusters of molecules. Center:When
conditions favor the formation of crystal
seeds,thedissolvedsugarmoleculescanjoin
many seeds, the resulting crystals are small,
and the candy texture is fine. Right:When
conditionslimittheformationofcrystalseeds,
thedissolvedsugarmoleculescanjoinonlya
fewseeds,theresultingcrystalsarelarge,and
thecandytextureiscoarse.
