Milk Composition

1. Unit-1 Milk composition and
components
Dairy Technology

2. Definitions of milk
 Acc to PDFA (Prevention of Food Adulteration) Act,
“A secretion derived from complete milking of
healthy milch animals. It shall be free of colostrums”
 Chemically,
“Milk is a substance in which fat is present in
emulsion, casien together with some minerals in colloidal
suspension while lactose, mineral salts and whey protiens
in watery solutions.”

3. Composition
 Varies in chemical composition
 Causes of variations:-
 Species of mammal
 Breed
 State of lactation
 Feed
 Health
 Season of the year

4. Factors affecting milk composition

5. 1. Species:
► Milk protein:
Rabbit's milk 10% while cow' milk 3.7%.
► Milk fat:
Cow's milk 3.5% while buffaloe's milk 7%.
2. Age:
► Old age decrease fat contents of milk.
3. Seasonal variation:
► In winter increase in fat, protein and mineral contents of milk.

6. 4. Nutritional variation:
► Overfeeding has no effect on milk composition.
► Underfeeding decrease in milk volume and protein and
lactose contents of milk while fat contents of milk
increased.
5. Infection of mammary gland:
► Mastitis (inflammation of breast) decrease fat, lactose and
casein contents of milk while protein and chloride ions
increased.

7. 6. Stage of lactation:
 Colostrum secreted during 1st week of lactation.
 Intermediate milk secreted during 1st month of lactation
except 1st week.
 Mature milk secreted during 1st year of lactation except 1st
month.
 Late milk secreted after 1st year of lactation.
 Watery in consistancy.
 Contains less protein, lipid, lactose and
vitamins.
 Contains more minerals than mature milk

8. Average Compositions (%)
Constituent Cow Buffalo Human
Water 87.20 82.76 87.43
Fat 3.7 7.38 3.75
Protein 3.5 3.6 1.63
Lactose 4.9 5.48 6.98
Ash 0.70 0.78 0.21
Total solids 12.80 17.24 12.57

9. Milk Components
Milk
Milk solids
Milk Solids-
Not-Fats
(MSNF)
proteins
Casien Whey Protein
Lactose Minerals
Fats
water

11. Milk is formed of:
1) Water: form 87%.
2) Solids: form 13%.
A- Organic constituents of milk.
1. Protein.
2. Lipid.
3. Carbohydrate.
B- Inorganic constituents of milk:
1. Minerals.
2. Vitamins.

12. 1- Protein:
 Milk protein less in human than in cow's milk.
 All milk protein synthesized in the mammary
gland.
 Milk protein of high coefficient digestibility (85
– 95%)
X 100
Amount of N2 absorbed
Total N2 in the protein

13. Characterized by:
1- Protein of high biological value as:
It contains all essential amino acids.
Easily digested.
Easily absorbed.
Easily metabolized.
2- Contain moderate amount of non essential amino acids to
decrease stress on body cells.
3- Essential to keep positive nitrogen balance (nitrogen intake
more than nitrogen output).
5- Essential to maintain growth of newborn.

14. 6. Total amount of protein differ according to species and
affect rate of growth of young:
e.g:
 Young rabbit reach double weight in 5 days as milk
protein 10 gm/dl.
 Young calf reaches double weight in 50 days as milk
protein 3.7 gm/dl.
 Young child reach double weight in 5 - 8 months as milk
protein 1.5 gm/dl.
 (1 dl=0.1 litre)

15. Types of Milk Proteins are:
1. Casein.
2. Lactalbumin.
3. Lactglobulin.
4. Milk enzymes.

16. 1) Casein
 It is the main and most dominant milk protein.
 It represents 25% in human's milk and 83% in cow's milk.
 It is a compound protein (Phospho-protein) of high
biological value.
 The high phosphate content of casein allows it to
associate with calcium and form calcium phosphate
salts.
So, at normal pH of fresh milk (6.6 pH)
casein present as insoluble Ca. caseinate
phosphate complex.

17. Casein
• Exists as micelles, made
up of calcium phosphate
and casein complexes
• 4 types are prevalent
• α- casein
• β- casein
• κ- casein
• γ- casein
• Alpha and beta casein are
complexed with calcium
and phosphate while
kappa casein stabilizes
micelles by surface
binding.

19.  Casein contains 0.7% phosphorous and 0.7% sulphur.
 Casein is suspended in milk in colloidal suspension
complex of casein micelles that are dispersed in the water
phase of milk.
 Casein micelles are spherical in shape and much smaller in
diameter than fat globules, and consists of a network of
casein sub-micelles, each one micelle contains 400-500
submicelles, bonded by calcium phosphate bridges.

20.  Casein : (Lactalbumin - Lactglobulin) ratio is 1:3
which facilitate its digestion.
1
=
Casein
3
Lactalbumin + Lactglobulin

21. Milk Proteins
1. Casein
2. Whey proteins
• Located in solutions in the serum phase of milk along with
minor proteins and enzymes
• Major whey proteins include
• Beta-lactoglobulin
• Alpha-lactalbumin
• Blood serum albumin
• Euglobin
• Pseudoglobulin
• immunoglobulins

22. Lactalbumin:
 Represent 87% of whey protein.
 Precipate by full saturation with ammonium sulphate.
 Rich in cysteine and cystine so give +ve result with
sulphur test.
 Simple protein.
 Soluble protein.
 Easily digested.
 Consists of two fractions:
α Lactalbumin 32% of whey protein.
β lactglobulin 55% of whey protein.

23. Lactglobulin:
 Represent 13% of whey protein.
 Precipate by half saturation with ammonium sulphate
solution.
 Rich in cystein and cystin so give +ve result with sulpher
test.
 Simple protein.
 Soluble protein.
 Easily digested.

24.  Consists of two fractions:
 True globulin (Euglobulin) 50%.
 False globulin (Pseudoglobulin) 50%.
 They carry antibodies causing immunity so called
immunoglobulins.
 They present in higher concentration in colostrum.

25. Milk proteins
 Enzymes include
 Lactoperoxidase
 Lactotransferrin
 Lysozyme
 Glycoprotein
 Serum transferrin

26.  Also includes
1. Catalase.
2. Peroxidase.
3. Xanthin oxidase.
4. Alkaline phophatase.
5. Amylase.
6. Lipase.
7. Aldehyde oxidase.

27. Beside milk proteins milk also contains:
A) Lactoferrin binding protein:
 It contains iron which is bounded to a glycoprotein.
 It facilitates iron transport and storage.
 Found in high concentration in human colostrums and milk.
B) Vitamin B12 binding protein:
 It carries vitamin B12.
Lactoferrin and vitamin B12 binding protein deprive
pathogenic intestinal bacteria from iron and vitamin B12 so
they have bacteriostatic action.

28. Milk fats
 Occurs in microscopic globules in an oil-in-water type
emulsion
 Human's and cow's milk contain the same amount 3.5
gm/dl but buffalo's milk is a little higher 7 gm/dl.
 Easily separated on standing.
 Responsible for white color of milk
 Lipid content
 97-98%- triacylglycerols
 0.2-1%- phospholipids
 02-0.4%- Sterols and vitamin A, D, E and K along with
linoleic and linolenic acids.

29. Also contain small amounts of:
 phospholipids 0.1%.
 Milk phospholipids are lecithin, cephalin,
sphingomyelin (9:5:1).
 Phospholipids in cow's milk twice that of human
milk.
 Cholesterol 0.01%.
Cow's milk contains higher proportion (mainly free
form) than human milk mainly (ester form)
 Milk contain fat soluble substance:
e.g: Fat soluble vitamins (vitamin A) which is higher
in human milk than cow's milk.

30. Human's milk
Cow's milk
Contain no short chain fatty
acids.
Contain short chain fatty
acids 10%.
Contain 10% essential
(polyunsaturated) fatty acids
specially linoleic fatty acids.
Contain 0.05% essential
(polyunsaturated) fatty
acids.
Saturated fatty acids 48%.
Saturated fatty acids 58%.
Unsaturated fatty acids
52%.
Unsaturated fatty acids
42%.

31. Milk sugar
 Majorly Lactose is present (4.9 w/v)
 It is a reducing disaccharide consists of glucose and
galactose.
 Human's milk contains 7% lactose while cow's milk
contains 5% lactose.
 Mainly occur in two forms
 Alpha lactose
 Beta lactose
 Alpha lactose is less soluble than beta lactose.
 Beta lactose is more sweeter than alpha lactose
 Other sugars include glucose, galacatose and other
oligosaccharides.

32. Importance of lactose:
1. It is less sweet than sucrose so allow the baby to take
large amount of milk without causing nausea.
2. It is non fermentable carbohydrate so it doesn't produce
CO2 in GIT and the baby doesn't suffer from abdominal
colic or distention (stretch).
3. Lactose help growth of lactic acid producing bacteria so
help in absorption of Ca, P, Fe, Cu which prefer acidic
medium for their absorption.
4. Lactose inhibits growth of putrefactive (incompletely
oxidized product) bacteria which cause abdominal
distention by increasing the acidity of the intestine.

33. 5. On hydrolysis it produce glucose and
galactose:
 Glucose act as source of energy.
 Galactose used for synthesis of
galactolipids so help in development of
nerve tissues.
Lactose level in milk tend to vary directly with the weight of
the adult brain:
Man has the largest brain in proportion to the body weight
of all animals this may be related to the galactolipids of
the brain which contains galactose.

34. 6. Lactose has a laxative effect (aiding
digestion) as some of glucose is
fermented by the intestinal bacteria
producing CO2 which stimulate the
intestinal movement.

35. If the milk is taken by the adult in large
amount result in diarrhea due to limited
supply of lactase enzyme, so lactose is
hydrolyzed by intestinal bacteria to glucose
and galactose.
Glucose is fermented producing CO2 and
abdominal distention.
Non fermentable galactose and
unhydrolyzed lactose increase osmotic
pressure of the intestine leads to diarrhea.

36. B-Inorganic constituents of milk

37. Milk Salts
 Major elements
 Calcium
 Potassium
 Phoshate
 Citrate
 Chlorine
 Require for
 Heat stability and alcohol coagulation of milk
 Age thickening of condensed milk
 Feathering of coffee cream
 Renin coagulation

38. 1- Minerals:
 Human milk contain less mineral elements (0.4%) than
cow's milk (0.8%).
 Milk rich in Ca and P which are present in their proper
ratio for absorption (2:1) in human milk while in cow's
milk (1:2) which is not suitable for their maximum
absorption .
 Ca and P are essential for:
1. Growth of bone and teeth.
2. Stability of casein.

39.  Milk is deficient in Fe and Cu which are supplied by their
storage in liver during prenatal life (this store is sufficient till
weaning-start to independent from mother).
 Milk is deficient in Iron but it is more in human milk than
cow's milk Thus anaemia (reduction of oxygen transport)in
breast feeding is less common.
 Milk contain adequate amount of Na, K, Mg.
 Human milk contains Na:K (1:2) which is suitable for the
optimal growth of newborn.

40. Vitamins
 Major vitamin present
 Vitamin B1,B2, B6, B12
 Vitamin D
 Vitamin E
 Vitamin K
 Folic acids
 Ash(0.7%)
 White residue after incineration of a given weight of milk
 Used as measure of mineral content of milk
 Other components
 WBCs
 Mammary gland cells
 Various bacteria

41. 2- Vitamins:
 Milk is deficient in:
 Vitamin C.
 Vitamin D.
 Vitamin K.
 Milk contain adequate amount of vitamin B complex
which are sufficient for first week of life
e.g:
 Pantothenic acid.
 Riboflavin (gives the whey the greenish tint in
sunlight).

42.  Vitamin C must be supplied to the growing baby in the form
of fruit juices to withstand infection.
 Fortified vitamin D milk is used in order to supply the baby
with vitamin D requirement which is added from cod liver
oil.
 Exposure to sunlight in the early morning or before sunset
help in formation of active vitamin D from cholesterol.

43. Water
 For all animals, water is the nutrient required in the
highest quantity, and milk contains a lot of water
(88.6%).
 This amount of water is controlled by the amount of
lactose synthesized by the secretory cells of the
mammary gland.

44. Milk is an adequate diet for
children
Although milk is deficient in Fe, Cu, vitamin C, vitamin D,
and vitamin K it is complete natural food for the following
reasons:

45. 1. Easily digested absorbed and metabolized.
2. Contain all the nutrients required for the newborn at early
stage of life.
3. Balanced ratio between carbohydrates, lipid and protein.
4. Milk protein:
Protein of high biological value as:
 It contains all essential amino acids.
 Easily digested.
 Easily absorbed.
 Easily metabolized.

46. 5. Milk lipid:
Milk contain essential fatty acids
e.g:
 Linoleic acid.
 Linolenic acid.
6. Milk sugar (lactose):
A. It is less sweet than sucrose so allow the baby to take large
amount of milk without causing nausea.
B. It is non fermentable carbohydrate so it doesn't produce
CO2 in GIT and the baby doesn't suffer from abdominal
colic or distention.
C. Lactose help growth of lactic acid producing bacteria so
help in absorption of Ca, P, Fe, Cu which prefer acidic
medium for their absorption.

47. D. Lactose inhibits growth of putrefactive bacteria which cause
abdominal distention.
E. On hydrolysis it produce glucose and galactose.
F. Lactose has a laxative effect.
7. Provide Ca and P in proper ratio for absorption (2:1)
which are essential for:
1. Growth of bone and teeth.
2. Stability of casein.
8. Good source of vitamins.
9. Contain antibodies specially in colostrums which
provide immunity to the newborn.
10. Cheep in price and of good caloric value.

48.  Certain foreign substance in the blood
plasma may enter the milk as:
 Volatile oils of certain foods (onions –
garlic).
 Drugs (sulphonamids – salicylate –
morphin – alcohol).
 Inorganic elements (iron – iodine – lead –
mercury).

49. Types of milk
 1. “Flavoured Milk” by whatever name called may contain
nuts(whole fragmented or ground) chocolate, coffee or any
other edible flavour, edible food colours and cane sugar.
 Flavoured milk shall be pasteurized, sterilized or boiled.
 2. “Full Cream Milk” means milk or a combination of
buffalo or cow milk or a product prepared by combination of
both that has been standardized to fat and solids-not-fat (SNF)
percentage, by adjustment/addition of milk solids, Full cream
Milk shall be pasteurized.
 It shall show a negative phosphatase test. It shall be packed in
clean, sound and sanitary containers properly sealed so as to
prevent contamination.

50.  3. “Mixed milk” means a combination of milk of cow.
Buffalo, sheep, goat or any other milch animal and may
be a combination of any of these milk which has been
made and conforms to the standards.
 4. “Milk Products” means the products obtained from
milk such as cream, malai, curd, skimmed milk curd,
cheese unsweetened, condensed skimmed milk-sweetened
and unsweetened, milk powder, skimmed milk powder,
partly skimmed milk powder, infant milk food, table
butter and desi butter.

51.  5. “Recombined milk” means the homogenized
product prepared from milk fat, non-fat milk solids and
water. Recombined milk shall be pasteurized and shall
show a negative phosphatase test.
 6. “Skimmed milk” means the product prepared from
milk from which almost all the milk fat has been
removed mechanically.

52. Thank You…!