some floating free, some embedded in the
membranes of the fat globules. Pasteurization
(p. 22) greatly reduces this vitality; in fact
residual enzyme activity is taken as a sign that
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. But the dynamism of raw milk is prized
in traditional cheese making, where it
contributes to the ripening process and
deepens flavor.
The making of milk. Cells in the cow’s
mammary gland synthesize the components of