Milk
Fat
Chemistry
Milk
contains
approximately
3
.
4%
total
fat
.
The
major
fatty
acids
in
milk
fat
are
____________________
chain
fatty
acids
that
are
____________________
(
65%
)
and
have
4
to
18
carbons
,
monounsaturated
fatty
acids
(
30%
)
,
and
polyunsaturated
fatty
acids
(
5%
)
.
Some
of
the
fatty
acids
are
found
in
very
small
amounts
but
contribute
to
the
unique
and
desirable
____________________
of
milk
fat
and
butter
.
The
fatty
acid
composition
of
milk
fat
is
not
constant
throughout
the
cow's
____________________
cycle
.
The
fatty
acids
that
are
4
to
14
carbons
in
length
are
made
in
the
____________________
gland
of
the
animal
.
Some
of
the
16
carbon
fatty
acids
are
made
by
the
animal
and
some
come
from
the
animal's
____________________
.
All
of
the
18
carbon
fatty
acids
come
from
the
animal's
diet
.
There
are
systematic
changes
in
milk
fat
composition
that
are
____________________
to
the
stage
of
____________________
and
the
energy
needs
of
the
animal
.
In
early
lactation
,
the
animal's
energy
comes
largely
from
body
stores
and
there
are
limited
fatty
acids
available
for
fat
____________________
,
so
the
fatty
acids
used
for
milk
fat
production
are
obtained
from
the
diet
and
tend
to
be
the
longer
chain
fatty
acids
.
Later
in
lactation
more
of
the
fatty
acids
in
milk
are
formed
in
the
mammary
gland
so
that
the
concentration
of
the
short
chain
fatty
acids
such
as
4
:
0
and
6
:
0
are
____________________
than
they
are
in
early
lactation
.
The
fatty
acids
are
arranged
on
the
triglyceride
molecule
in
a
specific
manner
.
Most
of
the
____________________
chain
fatty
acids
are
at
the
bottom
carbon
position
of
the
triglyceride
molecule
,
and
the
longer
fatty
acids
tend
to
be
in
the
____________________
and
top
positions
.
The
distribution
of
the
fatty
acids
on
the
triglyceride
backbone
affects
the
flavor
,
physical
,
and
nutritional
properties
of
milk
fat
.
Milk
Fat
Physical
Properties
The
triglycerides
of
milk
fat
are
in
the
form
of
____________________
.
The
globules
are
surrounded
by
a
____________________
and
____________________
membrane
that
stabilizes
the
globules
in
the
serum
(
water
)
phase
of
milk
.
The
native
globules
range
in
size
from
less
than
1
µm
to
over
10
µm
.
The
uneven
size
distribution
allows
the
larger
globules
to
float
in
a
process
called
____________________
,
thus
resulting
in
a
?
cream
____________________
?
at
the
top
of
the
container
.
Milk
is
homogenized
to
____________________
the
size
of
the
large
globules
to
less
than
1
µm
,
create
a
uniform
distribution
of
globules
throughout
the
serum
phase
,
and
minimize
creaming
.
Deterioration
of
Milk
Fat
Milk
fat
can
be
degraded
by
____________________
action
,
exposure
to
____________________
,
and
____________________
.
Each
of
these
processes
proceeds
through
different
mechanisms
.
Enzymes
that
degrade
fat
are
called
____________________
,
and
the
process
is
called
lipolysis
.
Milk
lipases
come
from
several
sources
:
the
____________________
milk
,
airborne
bacterial
____________________
,
bacteria
that
are
added
intentionally
for
fermentation
,
or
____________________
cells
present
in
milk
.
Lipases
remove
fatty
acids
from
the
glycerol
backbone
of
the
triglyceride
.
Usually
the
action
of
lipase
causes
____________________
rancid
flavors
in
milk
.
Pasteurization
____________________
lipases
and
increases
the
____________________
life
of
milk
.
However
,
in
some
cheeses
,
such
as
blue
cheese
and
provolone
,
a
small
amount
of
____________________
is
needed
to
____________________
the
characteristic
flavor
.
Light
induced
degradation
can
happen
fairly
rapidly
in
milk
and
produces
a
characteristic
off
-
flavor
.
The
majority
of
this
off
-
flavor
is
caused
by
protein
degradation
.
Storing
milk
in
____________________
containers
minimizes
this
process
.
Milk
fat
can
also
be
degraded
by
a
classical
chemical
oxidation
mechanism
,
the
attack
on
double
bonds
in
the
fatty
acids
by
oxygen
.
Oxidation
of
the
unsaturated
phospholipids
in
milk
produces
off
-
flavors
that
are
described
as
painty
,
fishy
,
or
metallic
.
