On food and cooking the science and lore of the kitchen ( PDFDrive ) 40

some floating free, some embedded in the
membranesofthefatglobules.Pasteurization
(p. 22) greatly reduces this vitality; in fact
residualenzymeactivityistakenasasignthat
the heat treatment was insufficient.
Pasteurized milk contains very few living
cells or active enzyme molecules, so it is
more predictably free of bacteria that could
cause food poisoning, and more stable; it
develops off-flavors more slowly than raw
milk.Butthedynamismofrawmilkisprized
in traditional cheese making, where it
contributes to the ripening process and
deepensflavor.

The making of milk. Cells in the cow’s
mammaryglandsynthesizethecomponentsof


milk, including proteins and globules of milk
fat, and release them into many thousands of
small compartments that drain toward the
teat. The fat globules pass through the cells’
outer membranes, and carry parts of the cell
membraneontheirsurface.
Milkowesitsmilkyopalescenceto
microscopicfatglobulesandproteinbundles,
whicharejustlargeenoughtodeflectlight
raysastheypassthroughtheliquid.Dissolved
saltsandmilksugar,vitamins,otherproteins,
andtracesofmanyothercompoundsalso

swiminthewaterthataccountsforthebulkof
thefluid.Thesugar,fat,andproteinsareby
farthemostimportantcomponents,andwe’ll
lookatthemindetailinamoment.
Firstafewwordsabouttheremaining
components.Milkisslightlyacidic,withapH
between6.5and6.7,andbothacidityandsalt
concentrationsstronglyaffectthebehaviorof
theproteins,aswe’llsee.Thefatglobules
carrycolorlessvitaminAanditsyellow-