On food and cooking the science and lore of the kitchen ( PDFDrive ) 1158

(p.583).
SwellingandGelationWhatmakesstarchso
usefulisitsbehaviorinhotwater.Mixsome
flourorcornstarchintocoldwater,and
nothingmuchhappens.Thestarchgranules
slowlyabsorbalimitedamountofwater,
about30%oftheirownweight,andthey
simplysinktothebottomofthepotandsit
there.Butwhenthewatergetshotenough,the
energyofitsmoleculesissufficienttodisrupt
theweakerregionsofthegranule.The
granulesthenabsorbmorewaterandswellup,
therebyputtinggreaterandgreaterstresson
themoreorganized,strongergranuleregions.
Withinacertainrangeoftemperatures
characteristicofeachstarchsourcebut
usuallybeginningaround120–140ºF/50–60ºC,
thegranulessuddenlylosetheirorganized
structure,absorbagreatdealofwater,and
becomeamorphousnetworksofstarchand
waterintermingled.Thistemperatureiscalled
thegelationrange,becausethegranules


becomeindividualgels,orwater-containing
meshworksoflongmolecules.Thisrangecan
berecognizedbythefactthattheinitially
cloudysuspensionofgranulessuddenly
becomesmoretranslucent.Theindividual
starchmoleculesbecomelesscloselypacked
togetheranddon’tdeflectasmanylightrays,

andsothemixturebecomesclearer.
Thickening: The Granules Leak Starch
Depending on how concentrated the starch
granules are to begin with, the starch-water
mixture may noticeably thicken at various
points during their swelling and gelation.
Most sauces are rather dilute (less than 5%
starchbyweight)andthickenduringgelation,
when the mixture begins to become
translucent. They reach their greatest
thickness after the gelated granules begin to
leakamyloseandamylopectinmoleculesinto
the surrounding liquid. The long amylose
molecules form something like a three-