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On food and cooking the science and lore of the kitchen ( PDFDrive ) 1509

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animalfatsaround375ºF/190ºC.Fatsthat
containothersubstances,suchasemulsifiers,
preservatives,andinthecaseofbutter,
proteinsandcarbohydrates,willsmokeat
lowertemperaturesthanpurefats.Fat
breakdownduringdeepfryingcanbeslowed
byusingatall,narrowpanandsoreducingthe
areaofcontactbetweenfatandatmosphere.
Thesmokepointofadeep-fryingfatis
loweredeverytimeit’sused,sincesome
breakdownisinevitableevenatmoderate
temperatures,andtrouble-makingparticlesof
foodarealwaysleftbehind.
Emulsifiers:Phospholipids,Lecithin,Monoglycerides

Someveryusefulchemicalrelativesofthe
truefats,thetriglycerides,arethe
diglyceridesandmonoglycerides.These
moleculesactasemulsifierstomakefine,
cream-likemixturesoffatandwater—such
saucesasmayonnaiseandhollandaise—even


thoughfatandwaterdon’tnormallymixwith
eachother.Themostprominentnatural
emulsifiersarethediglyceridephospholipids
ineggyolks,themostabundantofwhichis
lecithin(itmakesupaboutathirdoftheyolk
lipids).Diglycerideshaveonlytwofatty-acid
chainsattachedtotheglycerolframe,and
monoglyceridesjustone,withtheremaining


positionsontheframebeingoccupiedby
smallpolargroupsofatoms.Thesemolecules
arethuswater-solubleatthehead,andfatsolubleatthetail.Incellmembranes,the
phospholipidsassemblethemselvesintwo
layers,withonesetofpolarheadsfacingthe
wateryinterior,theothersetthewatery
exterior,andthetailsofbothsetsminglingin
between.Whenthecookwhiskssomefatinto
awater-basedliquidthatcontainsemulsifiers
—oilintoeggyolks,forexample—thefat
formstinydropletsthatwouldnormally
coalesceandseparateagain.Butthe
emulsifiertailsbecomedissolvedinthe



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