On food and cooking the science and lore of the kitchen ( PDFDrive ) 1174
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Someofthemostdelicioussaucesweeat,
includingtomatosaucesandapplesauce,are
madesimplybycrushingfruitsand
vegetables.Crushing,orpureeing,freesthe
juicesfromthecellsofthefruitorvegetable,
andbreaksthecellwallsintofragmentsthat
becomesuspendedinthejuicesandblock
theirflow,sogivingthemsomethickness.
Crushednutsandspiceshavenojuicesof
theirown,buttheythickenaliquidtowhich
they’readdedbyabsorbingsomeofitswater
andprovidingdrycellparticlesthatobstruct
theliquid’sflow.
Untilrecently,mostpureesofplanttissue
wouldhavebeenmadebycookingthetissue
tosoftenit,andtheneithergrindingitina
mortarorforcingitthroughafinesieve.Raw
pureescouldonlybemadefromfruits
softenedbyripening,orfrombrittlenuts.
Today’scookscanusepowerfulmachines—
blenders,foodprocessors—topureeanyfruit
orvegetableorseedwithease,whether
they’reraworcooked.
PlantParticles:Coarse
andInefficientThickeners
Comparedtotheotherwaysofthickening,
simplepureeingtendstoproduceacoarse
saucethatmorereadilyseparatesintosolid
particlesandthinfluid.Thesolidfragments
ofplantcellwallsareclumpsofmany
thousandsofcarbohydrateandprotein
molecules.Ifthosemoleculesweredispersed
separatelyandfinelythroughoutthefluid—
asgelatinorstarchmoleculesareinother
sauces—theywouldbindmanymorewater
molecules,gettangledupineachother,and
befartoosmallforthetonguetodetectas
particles.Butplant-cellfragmentsrangefrom
0.01to1millimeteracross;theygiveagrainy
impressiononthetongueandthey’refarless
efficientthanindividualmoleculesatbinding
waterorinterferingwithfluidflow.And
