On food and cooking the science and lore of the kitchen ( PDFDrive ) 1007

theamountofsolidmaterialinagiven
volumeandmakingthebreadorcakeless
dense,morelightandtender.
Yeasts

Humanshavebeeneatingraisedbreadsfor
6,000years,butitwasn’tuntilthe
investigationsofLouisPasteur150yearsago
thatwebegantounderstandthenatureofthe
leaveningprocess.Thekeyisthegasproducingmetabolismofaparticularclassof
fungus,theyeasts.Theword“yeast,”
however,isasoldasthelanguage,andfirst
meantthefrothorsedimentofafermenting
liquidthatcouldbeusedtoleavenbread.
FoodWords:LeaveningandYeast
Leavening comes from an Indo-European
root meaning “light, having little weight.”
Related words from the same root include
levity,lever,relieve,andlung.Yeastcomes


from a root word that meant “to seethe,
boil, bubble over.” This derivation
underlines the way in which fermentation
seemed to be a kind of cooking of the
cerealgruel,atransformationfromwithin.
Theyeastsareagroupofmicroscopic
single-celledfungi,relativesofthe
mushrooms.Morethan100differentspecies
areknown.Somecausehumaninfections,
somecontributetofoodspoilage,butone

speciesinparticular—Saccharomyces
cerevisiae,whosenamemeans“brewer’s
sugarfungus”—isputtogooduseinboth
brewingandbaking.Formuchofhuman
history,yeastwassimplyrecruitedfromthe
grainsurfaceorsuppliedbyanearlierpieceof
dough,orobtainedfromthesurfaceofbeer
brewingvats.Todaystrainsespecially
selectedforbreadmakingaregrownon
molassesinindustrialfermentationtanks.
Yeast Metabolism Yeasts metabolize sugars