On food and cooking the science and lore of the kitchen ( PDFDrive ) 1498

hydrogen ions, which are the basic units of
positive charge (protons), can have drastic
effects on other molecules in solution. A
structure that is stable with a few protons
around may be unstable when many protons
areinthevicinity.Sosignificantistheproton
concentration that humans have a specialized
taste sensation to estimate it: sourness. Our
termfortheclassofchemicalcompoundsthat
release protons into solutions,acids, derives
from the Latinacere, meaning to taste sour.
We call the complementary chemical group
that accepts protons and neutralizes them,
basesoralkalis.
Thepropertiesofacidsandbasesaffectus
continuallyinourdailylife.Practicallyevery
foodweeat,fromsteaktocoffeetooranges,
isatleastslightlyacidic.Andthedegreeof
acidityofthecookingmediumcanhavegreat
influenceonsuchcharacteristicsasthecolor
offruitsandvegetablesandthetextureof
meatandeggproteins.Somemeasureof


aciditywouldclearlybequiteuseful.A
simplescalehasbeendevisedtoprovidejust
that.
ThepHScaleThestandardmeasureofproton
activity in solutions ispH, a term suggested
by the Danish chemist S. P. L. Sørenson in
1909. It’s essentially a more convenient

version of the minuscule percentages of
moleculesinvolved(forsomedetails,seebox
below). The pH scale runs from 0 to 14. The
pHofneutral,purewater,withequalnumbers
of protons and OH ions, is set at 7. A pH
lowerthan7indicatesagreaterconcentration
of protons and so an acidic solution, while a
pH above 7 indicates a greater prevalence of
proton-accepting groups, and so a basic
solution. Here’s a list of common solutions
andtheirusualpH.
Liquid pH
Humangastricjuice 1.3–3.0