On food and cooking the science and lore of the kitchen ( PDFDrive ) 1185

liquid,
and
give
emulsions
their
characteristicallymilkyappearance.
Themoredropletsthatarecrowdedinto
thecontinuousphase,themoretheygetinthe
water’sandeachother’sway,andthemore
viscoustheemulsionis.Inlightcream,thefat
dropletstakeupabout20%ofthetotal
volumeandwater80%;inheavycream,the
dropletsareabout40%ofthevolume;andin
stiff,semisolidmayonnaise,oildroplets
occupynearly80%ofthevolume.Ifthecook
worksmoreofthedispersedliquidintothe
emulsion,thenitgetsthicker;ifheaddsmore
ofthecontinuousliquid,thenthere’smore
spacebetweendroplets,andtheemulsion
becomesthinner.Clearlyit’simportantto
keepinmindwhichphaseiswhich.
Becausenearlyallemulsifiedsaucesare
oil-in-watersystems,I’llassumeinmostof
thefollowingdiscussionthatthecontinuous
phaseiswater,thedispersedphaseoil.


FormingEmulsions:OvercomingtheForce
ofSurfaceTensionIttakesworktomakean
emulsion. We all know from experience that
when we pour water and oil into the same

bowl, they form two separate layers: one
doesn’tjustturnintotinydropletsandinvade
theother.Thereasonforthisbehavioristhat
when liquids can’t mix for chemical reasons,
they spontaneously arrange themselves in a
way that minimizes their contact with each
other. They form a single large mass, which
exposes less surface area to the other liquid
than does the same total mass broken into
pieces. This tendency of liquids to minimize
theirsurfaceareaisanexpressionoftheforce
calledsurfacetension.

Mayonnaise formation. Two stages in making
mayonnaise as seen through a light
microscope. One tablespoon/15 ml of oil