On food and cooking the science and lore of the kitchen ( PDFDrive ) 1010
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materialsurroundingthemmustbeelastic
enoughtocontainitforthatmuchtime.Weak
doughsandrunnybatterscan’tholdgas
bubblesformorethanafewminutes,andare
thereforeusuallyraisedwithafaster-acting
gassource.Thisistheroleplayedby
chemicalleavenings.Theseingredientsare
concentrated,andsmalldifferencesinthe
amountaddedcancauselargevariationsin
thequalityofthefinishedfood.Toolittle
leaveningwillleaveitflatanddense,while
toomuchwillcausethebattertooverexpand
andcollapseintoacoarsestructurewitha
harshflavor.
Nearlyallchemicalleaveningsexploita
reactionbetweencertainacidicandalkaline
compoundsthatresultsintheproductionof
carbondioxide,thesamegasproducedby
yeast.Thefirstchemicalleaveningwasa
driedwaterextractofwoodash—potash,
mainlypotassiumcarbonate—whichreacts
withthelacticacidinasoureddoughas
follows:
2(C3H6O3)+K2CO3 2(KC3H5O3)+H2O+
CO2(2moleculesoflacticacidplus1of
potassiumcarbonateyield2moleculesof
potassiumlactate,plusamoleculeofwater,
plusamoleculeofcarbondioxide)
TheAcidComponentsofBaking
Powders
Some of these acids are available only to
manufacturers.
Most
double-acting
supermarketbakingpowdersareamixture
of sodium bicarbonate, MCP, and SAS.
Single-acting powders omit the SAS, and
the MCP is coated to delay its release
artificially.
LeaveningAcid TimeofReaction
Creamoftartar,
Immediately,during
tartaricacid
mixing
Monocalcium
Immediately,during
