Understanding Food
Chapter 11:
Milk
Composition of Milk

The basic composition
of milk regardless of
the source remains the
same:
 Water 87.3%
 Carbohydrate 4.8%
 Protein 3.4%
 Fat 3.7%
 Minerals 0.8%
Composition of Milk


Casein: The primary protein
(80%) found in milk; it can be
precipitated (solidified out of
solution) with acid or certain
enzymes.
Whey: The liquid portion of
milk, consisting primarily of
93% water, lactose, and whey
proteins (primarily lactalbumin
and lactoglobulin).
Purchasing Milk

Milk is graded according to its bacterial
count.

The law requires that all Grade A milk
and milk products crossing state lines
must be pasteurized.

Grading is voluntary and is paid for by
the dairy industry.
Purchasing Milk


Ultrapasteurization: A process in which a milk product is
heated at or above 280°F (138°C) for at least two seconds.
Ultrahigh-temperature (UHT) Milk: Milk that has been
pasteurized using very high temperatures, is aseptically sealed,
and is capable of being stored unrefrigerated for up to three
months.
Purchasing Milk

Homogenization:
A mechanical
process that breaks
up the fat globules
in milk into much
smaller globules
that do not clump
together and are
permanently
dispersed in a very
fine emulsion.
Types of Milk

About half the milk produced in the
United States is sold as fluid milk and
cream.

Imitation milk: A product defined by
the FDA as having the appearance,
taste, and function of its original
counterpart but as being nutritionally
inferior.
Types of Milk
 Evaporated
milk
 60%
of water evaporated
 sterilized
 Sweetened
 50%
condensed milk
of water evaporated
 40-45% sugar by weight
 Sterilzation not needed
Types of Milk
Cultured or fermented milk products
have been used for centuries.
 Some cultured milk products commonly
consumed in North America are:
 Buttermilk
 Yogurt
 Acidophilus milk

Types of Milk


Probiotics: Live microbial food ingredients
(i.e., bacteria) that have a beneficial effect
on human health.
Prebiotics: Nondigestible food ingredients
(generally fibers such as
fructooligosaccharides (FOS) and inulin) that
support the growth of probiotics.
Milk Products in Food
Preparation



Flavor Changes
The bland, slightly sweet flavor of milk comes from
its lactose, salts, sulfur compounds, and short-chain
fatty acids.
The percentage of fat determines the mouthfeel and
body of a particular milk.
Exposure to heat or sunlight, oxidation, the use of
copper equipment or utensils, and the feed ingested
by the source animal are just some of the other
factors that can influence the flavor of milk.
Milk Products in Food
Preparation
Coagulation and precipitation
 Scorching
 Skin formation
 Acid
 Curdling

Milk Products in Food
Preparation

Whipped Milk
Products
During whipping,
the protein in these
milk products is
mechanically
stretched into thin
layers that trap air
bubbles, fat
particles, and liquid.
Storage of Milk Products
Refrigerated
 All
fluid milk except unopened,
aseptic packs of ultrahightemperature pasteurized milk
and certain canned milk
products should be stored in
the refrigerator.
Storage of Milk Products
Dry Storage





Nonfat dry milk stored away from moisture and in
tightly closed containers will keep for about one year.
Unopened cans of evaporated and sweetened
condensed milks will keep up to a year in dry,
ventilated areas, double that if refrigerated.
Ultrapasteurized milk can be stored unopened at
room temperature for up to three months.
They should all be stored at or slightly below room
temperature (72°F/22°C).
Once opened, all these milks must be refrigerated.