On food and cooking the science and lore of the kitchen ( PDFDrive ) 1187

possible,anddiluteitwithanyother
ingredientsaftertheemulsionhasformed.
Thesecondfactorthatmakesiteasierto
producesmalldropletsinanemulsionisthe
presenceofemulsifiers.
Emulsifiers: Lecithin and Proteins
Emulsifiers are molecules that lower the
surface tension of one liquid dispersed in
another,andthereforemakeiteasiertomake
small droplets and a fine, creamy emulsion.
They do so by coating the surface of the
droplets, and shielding the droplet surface
from the continuous liquid. Emulsifiers are
therefore a true liaison: they must be partly
soluble in each of the two mutually
incompatible liquids. They manage this by
having two different regions on the same
molecule, one soluble in water and the other
infat.
Therearetwogeneralkindsofmolecules
thatcanactasemulsifiers.Onekindis


typifiedbytheeggphosopholipidlecithin.
Thesearerelativelysmallmoleculeswitha
fat-liketailthatburiesitselfinthefatphase
andanelectrically-chargedheadthatis
attractedtowatermolecules(p.802).The
otherkindofemulsifieristheproteins,which
aremuchlargermolecules,longchainsof
aminoacidsthathaveanumberofdifferent

fat-compatibleandwater-compatibleregions.
Theyolkproteinsineggsandthecasein
proteinsinmilkandcreamarethebest
proteinemulsifiers.

Unstableandstableemulsions.Oilandwater
are incompatible substances; they can’t mix
evenly with each other. When oil is whisked
into water, the resulting oil droplets tend to