Milk is the mammary gland secretion of female mammals. It consists mainly of water, milk fat, lactose, protein, and minerals. Cow's milk typically contains 87% water, 4% fat, and 9% non-fat solids. Milk can be categorized based on fat content (whole, skimmed, toned, double-toned) and processing (pasteurized, homogenized). Common analytical tests for milk include determining total solids, fat, pH, and specific gravity. Fat content is typically measured using the Gerber, Rose-Gottlieb, or acid digestion methods.

1. MILK
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2. WHAT IS
MILK?
 Milk is normal mammary gland secretion of female
mammals or it can be specifically said as the whole,
fresh lacteal secretion obtained by the complete
milking of one or more healthy cows, excluding that
obtained within 15 days before and 5 days after calving,
or such longer period as may be necessary to render
the milk practically colostrum free.
 It consists largely of water, milk fat, lactose or milk
sugar, protein and mineral matter.
 Milk is one of the most important foods in the human
diet because it has many components present in very
small quantities that are essential to growth and well-
being.
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3. WHAT DOES
MILK
CONTAIN?
 Milk primarily consists of water, non fat solid and fat.
 The composition may vary with each breed of the
cow.
 Composition may normally contain:
 Water – 87.3%
 Non-fat solid – 8.8%
 Fats – 3.9%*
 *Buffalo milk contain 7.44%
 Cow milk contain 3.66%
Water
87%
Fat
4%
Non fat
solid
9%
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4. VARIATION IN
COMPOSITION
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5. TYPESOF
MILK
MILK
COMMERCIAL
PASTEURISED
MILK
HOMOGENISED
MILK
PRESENCE OF
FAT
WHOLE MILK
SKIMMED MILK
TONED MILK
DOUBLETONED 5

6. BASEDON
COMMERCIAL
USE
 PASTEURISED MILK
Milk is heated at a very high temperature to kill
the harmful bacteria without losing its flavor or
nutritional value. (161F for 15sec).
 HOMOGENISED MILK
Milk is processed and the fat globules in it are
broken, due to which the fat spreads evenly,
preventing the formation of the creamy layer on top.
However, the nutritional and fat content remains the
same.
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7. PRESENCE
OF FAT
 WHOLE MILK
Whole milk or full cream milk is full of flavor, is
much thicker and creamier and contains high amount
of fat. It is ideal for children, growing teenagers and
body builders. One glass of whole milk contains
approximately 3.5% milk fat (150 calories).
 SKIMMED MILK
Skimmed milk has almost zero fat content (0.3%
to 0.1%). Even though it contains all the nutrients of
whole milk, it gives only half the calories of full cream
milk. A glass of skimmed milk without sugar is around 80
calories. It is good for weight watchers.
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8.  TONED MILK
Toned milk is made by adding skimmed milk
powder and water to whole milk. It contains about
3.0% fat. It restricts the body from absorbing cholesterol
from the milk to quite an extent.Toned milk contains the
same amount and type of nutrition as whole milk does,
only minus the fat soluble vitamins. One glass of toned
milk contains 120 calories.The consistency is little
thinner than the whole milk.
 DOUBLETONED MILK
This milk is also obtained by adding skimmed
milk power to whole milk. It has about 1.5% fat content.
Double toned milk is ideal for those who are trying to
maintain weight and is recommended for heart patients.
The consistency is much thinner than toned milk
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9. OTHER
TYPESOF
MILK
Categorisation based on the milked animal:
 COW’S MILK
It is less thick and creamier, high on cholesterol
but low on fat and calories and is easily digestible.
Preferred for small children.
 BUFFALO’S MILK
It is much thicker and creamier, low on
cholesterol but high on fat and calories. Preserved
time is more as compared to cow’s milk. Ideal for dairy
products like khoya, paneer, sweets and other dairy stuff.
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10. MILK
PRODUCTS
 Butter
 Cheese
 Ice cream
 Margarine
 Dry milk powder
 Yogurt
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11. GENERAL
ANALYTICAL
METHODSOF
MILK
 The general tests include, tests for:
 Total solids
 Fats
 pH
 Specific gravity
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12. PREPARATION
OFSAMPLE
 Warm the sample to 37- 40°C by transferring it to the
beaker and keeping it in a water bath.
 Stir slowly for proper homogenisation.
 Mix sample thoroughly by pouring back into the bottle,
mixing to dislodge any residual fat sticking to the sides
and pour it back in the beaker. During mixing do not
shake the bottle vigorously.
 Allow the sample to come to room temperature (26-
28°C) and withdraw immediately for analysis.
 If small clots or lumps are observed in the sample a few
drops of liquor ammonia may be used.
 After homogenization, if the sample shows lumps or
clots are visible suggestive of curdling /splitting of
milk, the sample should be deemed unfit for analysis
and rejected.
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13. DETERMINATION
OFTOTALSOLIDS
(GRAVIMETRIC
METHOD)
 In this procedure, a known quantity of milk is dried on a
boiling water bath.
 Subsequently sample is dried in hot air oven at
102 ±2°C and from the weight of the residue, the total
solids content in milk is determined.
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15. DETERMINATION
OF FAT IN MILK
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METHODSTO
DETERMINE FAT
FROM MILK
GERBER METHOD
ROSE-GOTTLEIB
METHOD
ACID DIGESTION
METHOD (WERNER
SCHMIDT METHOD)

16. GERBER
METHOD
 The milk is mixed with sulphuric acid and iso-amyl
alcohol in a special Gerber tube, permitting
dissolution of the protein and release of fat.
 The tubes are centrifuged and the fat rising into the
calibrated part of the tube is measured as a
percentage of the fat content of the milk sample.
 The method is suitable as a routine or screening test.
 It is an empirical method and reproducible results can
be obtained if procedure is followed correctly.
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17. 17

18. ROSE-
GOTTLIEB
METHOD
 The milk sample is treated with ammonia and ethyl
alcohol; the former to dissolve the protein and the
latter to help to precipitate the proteins.
 Fat is extracted with diethyl ether and petroleum ether.
 Mixed ethers are evaporated and the residue
weighed.
 This method is considered suitable for reference
purposes.
 Strict adherence to details is essential in order to
obtain reliable results.
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20. ACID
DIGESTION
METHOD
(WERNER
SCHMIDT
METHOD)
 In this method, milk proteins are digested with
concentrated hydrochloric acid.
 Liberated fat is extracted with alcohol, ethyl ether
and petroleum ether.
 Ethers are evaporated and residue left behind is
weighed to calculate the fat content.
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22. pH
 pH of the milk should lie between 6.5 and 6.7.
 It can be analysed by potentiometric method.
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23. SPECIFIC
GRAVITY
 It has the value between 1.028-1.033.
 It can be analysed by lactometer.
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25. REFERENCES
 http://www.indushealthplus.com/milk-types-and-
variants.html
 The chemical analysis of foods and food products by
Morris B. Jacobs.
 http://old.fssai.gov.in/Portals/0/Pdf/Draft_Manuals/MIL
K_AND_MILK_PRODUCTS.pdf
 https://archive.org/details/gov.in.is.1479.2.1961
 www.googleimages.com
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