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DEFINITION AND COMPOSITION OF
MILK
 The normal secretion of the
mammary glands of all mammals.
 Milk is the lacteal and physiological
secretions of mammary glands
obtained from healthy cows or
buffaloes (excluding fifteen days
before and five days after
parturition)

and contains at least 3.5% fat and
8.5 solids-non fat.
 Milk is a complete food for the new
born.
 High density of nutritious
components.

 The basic composition of milk regardless of
the
source remains the same:
 Water 87.1%
 Carbohydrate 4.8%
 Protein 3.8%
 Fat 3.5%
 Minerals 0.8%

MILK
CARBOHYDRATE
 Lactose – main CHO
 Low solubility, may precipitate out
as grainy substance during heat
treatments
 Converts to lactic acid with souring
or fermentation – lactose stays in
whey
 Part of milk-solids-non fat
 Less sweet than sucrose

MILK
FAT
 3-4% for whole milk, varies according to breed
 Primarily triglycerides, then phospholipids,
sterols
 Mix of unsaturated, monounsaturated
and polyunsaturated fatty acids
 High level of short chain – contribute to
milk flavor
and low melting point of butter
 Fat globules less dense than water 
less stable
 “Creaming” process – fat rises to the

MILK
PROTEINS
CASEINS
 Casein is a complex protein that makes up 80
percent of the protein in milk. The casein micelle
makes many of the functions of casein possible,
such as ease of digestion and the growth and
development of the young. It is also necessary for
cheese-making and other food production
technologies.
 Can be separated by acidification
 Rennin- enzyme also precipitates casein clotting,
curdling when milk sours

MILK
WHEY
 When special enzymes are added to the
milk, it separates into curds (which are used
to make cheese) and liquid whey. The whey
protein is then pasteurized and dried so it
can be used as a key ingredient in some
drink mixes, protein bars and other foods.
Whey protein is generally safe and can help
to build muscle and strength, lose weight,
reduces appetite and boosts metabolism.
 Enzymes – lipase, protease,
alkaline phosphatase

MILK
VITAMINS
 Cow milk contains all water soluble B vitamins and is
an excellent source of riboflavin, pantothenic acid,
folates and vitamin B12. Moreover, bioavailability of
B vitamins in cow milk is good. It is high in vitamin
A and some D and contains small amounts of
vitamin C. Milk Vitamins play an important role in
intermediary metabolism as co-factors in numerous
enzymatic reactions or in non- enzymatic
physiological functions such as the visual process
(vitamin A), as antioxidants (carotenoids, vitamins E,
C and riboflavin) and in regulation of calcium
metabolism (vitamin D).

MILK
MINERALS
 Calcium
 Phosphor
us
 Magnesiu
m
 Potassium
 Sodium
 Chloride
 Sulfur

MILK
PIGMENTS
 The vegetable colouring pigments
present in milk include carotene
and xanthophyll, grouped
together as carotenoids. Beta-
carotene which is found in the
grass where the cows graze on.
Carotenoid is a precursor of
vitamin-A which gets converted
into enterocytes and hepatocytes

FLAVOR OF
MILK
 Mouth feel due to emulsified fat,
colloidally dispersed proteins, lactose
and milk salts.
 Fresh milk contains acetone,
acetaldehyde, methyl ketones and short
chain fatty acids to provide aroma.
 Normally milk has a mild sweet flavor.
 Heat processing changes milk flavor.
 Milk flavor is affected by physical
condition of cow and composition of
the feeds being offered to animals.

OFF
FLAVORS
 Off-flavors commonly found in milk can
be classified in three basic categories -
the ABC's of off-flavor development.
Absorbed
- feedy, barny, cowy, unclean, weedy,
and musty.
 Main cause: pasture weeds
 Old or moldy feeds provide rancid or
bitter flavors.
 Oxidation of fat: oxidized

PASTEURIZATIO
N
 Heating every particle of milk to a
particular temperature in order to
destroy most of the pathogenic
microorganisms and deleterious
enzymes present in milk and to
cool down milk immediately at
40C.
 Destroys lipase which
catalyzes hydrolytic

TIME/TEMPERATURES of
PASTEURIZATION
 Use high temperature, short time
(HTST) 1620F, 71-720C for 15 seconds
 Low temperature, longer time
(LTLT), 1450F, 63-640C for 30
minutes
 Ultra-high temperature (UHT),
2800F, 135-1500C for 2-4 sec. May
develop cooked flavor.

STERILIZATION
 Only occurs with high
temperatures 121°C (250°F) for
15-30 minutes.
 Can be aseptically packaged;
no refrigeration until
opened.

HOMOGENIZATIO
N
 Prevents creaming; maintains more
uniform composition, optional
process.
 Mechanically reduces fat globule
size, increases number of fat
globules and permanently
emulsifies fat globules.
Reduces fat globules from 3-20µm to
<2µm.

FORTIFICATIO
N
 Whole milk - optional addition of Vit. A &
D
 Low fat milk, non-fat, low-fat
chocolate - must be fortified for Vit. A.
 Addition of Vit. D optional but
routinely practiced.
 To increase viscosity, appearance, and
nutritive value of low fat milk, non-fat
milk solids may be added.

VARIETIES OF MILK:
Fluid Milk
 Must be free of pathogenic bacteria.
 Fat content and % of MSNF subject to
food regulations.
 Flavored – same nutrients as milk to
which flavor added.
 Certified milk – limited distribution due to
cost and sanitary standards very high.
 Eggnog- mixture of dairy ingredients
(cream, milk) egg yolk containing
ingredients, nutritive carbohydrate

 Canned whole milk – homogenized, sterilized and
canned
aseptically.
 Frozen whole milk – homogenized, pasteurized,
fat separates when thawed and protein
denatured by freezing
 Skim or non-fat – as much fat as possible
removed, minimum of MSNF, fortified with
vitamin A.
Optional: vitamin D, emulsifiers, stabilizers.
 Low-fat milk – some fat removed, named according to

CONCENTRATED MILKS:
EVAPORATED MILK
 Concentrated through process
of evaporation.
 Evaporated in a vacuum
chamber.
 Whole or nonfat – 60% of H2O
is removed.
 Homogenized, fortified, canned
and sterilized.
 Increasingly less stable with progression
of concentration and heat may
coagulate . Reconstituted by 1:1 ratio.

CONDENSED
MILK
 Similar in content of evaporated
milk and no sugar is added.
 NOT sterilized.
 Perishable at temperatures above
450F.

SWEETENED CONDENSED
MILK
 Concentrated whole or non-fat milk.
 60% of H2O is removed.
 Sweetened with sucrose or dextrose prior
to concentration.
 40-45% sugar level, may cause grittiness.
 Pasteurized, not sterilized due to
high concentration of sugar.

DRIED
MILK
 Processed from whole or nonfat milk
(more common).
 Condensed and 2/3 of H2O is removed.
 Sprayed into heated vacuum chamber
and contains less than 5% moisture
level.
 Most non-fat milk is fortified.
 “Instant” or “agglomerated” – some
moisture added back and are pourable,
dispersible, in cold H2O.

CULTURED/FERMENTED MILK
& MILK PRODUCTS
 Cultured products fermented
by addition of bacterial
cultures viz. Streptococci and
Lactobacilli
 Ferment lactose to lactic acid;
create low pH to coagulate casein.
 Acidified products – souring milk
with acid, with or without
microorganisms.
 Cultured and acidified products
contain different amounts of lactic

BUTTERMIL
K
 Traditionally liquid left after churning
butter, differs from non-fat milk due to
content of phospholipids and proteins.
 Cultured buttermilk – pasteurized low fat
or non-fat milk with Lactobacilli and
Streptococci.
 Acidified buttermilk – lactic acid
producing bacteria, however, not
compulsory.
 Smooth cultured flavor, high acid
content and useful in cooking.

SOUR
CREAM
 Traditionally heavy cream soured.
 Pasteurized, homogenized and
fresh light cream.
 Coagulated similar to buttermilk.
 Flavors and stabilizers are added.
 Proteolytic bacterial enzyme
activity may cause bitter flavor
after 3-4 weeks.

YOGUR
T
 Cultured pasteurized dairy product with
Lactobacillus bulgaricus and
Streptococcus thermophiles.
 Sealed for live and active bacteria; at
least 100 million bacteria/gram at time
of manufacture.
 Yogurt with viable strains of bacteria eaten
in sufficient quantities some will survive
passage through stomach and release
lactase in the intestine.

OTHER
PRODUCTS
 Acidophilus Milk - pasteurized low-fat
or nonfat milk with Lactobacillus
acidophilus. Added bacteria can live in
intestine and produce number of B-
vitamins.
 Reduced Lactose Milk - pasteurized milk
treated with lactase and sweeter than
regular milk.
 Kefir– fermented dairy products, kefir
grain and beneficial bacteria are added
to milk.
 Koumiss – milk heated before
fermentation and ferments to yield soft
curd with yeasty sour curd with mild

MILK
SUBSTITUTES
 Imitation milk – combination of
several non-dairy ingredients and
nutritionally inferior to cow milk.
 Substitute milk – nutritionally
equivalent; reduced calories or fat,
usually milk derivatives (casein,
casein salts, whey).
 Filled milk – substitute milk with
milk fat replaced with vegetable
oil.

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