On food and cooking the science and lore of the kitchen ( PDFDrive ) 1453

steepingherbsandspicesinthem,andwhy
vinegarcanhelpremovegreasyfilmsfrom
varioussurfaces.
FoodWords:Vinegar,Acid,Acetic
Though it doesn’t look or sound related,
the wordvinegar comes from the same
root as bothacid andacetic: the IndoEuropeanak-,meaning“sharp.”(Theaigre
i nvinaigre was originally the Latin
acer.)Edge, acute, acrid, ester, andoxygen
are related words, oxygen because its
presence was once thought necessary to
makeanacid.
TheAceticFermentation

Ittakesthreeingredientstomakevinegar:an
alcoholicliquid,oxygen,andbacteriaofthe
genusAcetobacterorGluconobacter,mainly
A.pasteurianusandA.aceti.Thesebacteria
areamongthefewmicrobesthatareableto


usealcoholasanenergysource.Their
metabolismofalcoholleavesbehindtwobyproducts,aceticacidandwater.
CH3CH2OH+O2 CH3COOH+H2O
Alcohol+oxygen aceticacid+water
Aceticacidbacteriarequireoxygen,andso
liveonthesurfaceofthefermentingliquid,
wherewithothermicrobestheyformafilm
sometimescalledthe“mother.”Especially
thickfilmsarecreatedbyAcetobacter
xylinum,whichsecretesaformofcellulose.

(Suchmatsaresometimescultivatedand
eatenforthemselves;seep.509.)
Acetobacteriathriveinwarmconditions,so
vinegarfermentationsareoftencarriedoutat
relativelyhightemperatures,from82to
104ºF/28–40ºC.
Theconcentrationofalcoholinthestarting
liquidaffectstheaceticfermentationandthe
stabilityoftheresultingvinegar.Analcohol
concentrationaround5%willproducea
vinegarthatisaround4%aceticacid,whichis