On food and cooking the science and lore of the kitchen ( PDFDrive ) 1009

inthe1920s,hasbeenremovedfromthe
fermentationtankanddriedintogranules
withaprotectivecoatingofyeastdebris.
Theyeastcellsaredormantandcanbe
storedatroomtemperatureformonths.
Thecookreactivatesthembysoaking
theminwarmwater,105–110ºF/41–
43ºC,beforemixingthedough.Atcooler
soakingtemperatures,theyeastcells
recoverpoorlyandreleasesubstances
thatinterferewithglutenformation
(glutathione).
Instantdryyeast,aninnovationofthe
1970s,isdriedmorequicklythanactive
dryyeast,andintheformofsmall
porousrodsthattakeupwatermore
rapidlythangranules.Instantyeast
doesn’tneedtobeprehydratedbefore
mixingwithotherdoughingredients,and
producescarbondioxidemorevigorously
thanactivedryyeast.


AnUnusualChemicalLeavening:
Hartshorn
Theleaveningthatdoesn’tinvolveanacidbase reaction is ammonium salts —
ammoniumcarbonateand/orcarbamate—
which were once known as “hartshorn”
because they were produced by the
distillationofdeerantlers.(Hartshornwas
also a common source of gelatin.) When

thesecompoundsareheatedto140ºF/60ºC,
they decompose into two leavening gases,
carbon dioxide and ammonia, and don’t
producewater.They’reespeciallysuitedto
thin, very dry cookies and crackers with a
large surface area to release the pungent
ammoniaduringbaking.
BakingPowdersandOther
ChemicalLeaveners

Yeastcellsproducecarbondioxideslowly,
overthecourseofanhourormore,sothe