Milk analysis

Topic :MILK
Presented by,
R.Venkatesan.
M.Pharm 1st semester
Dept. pharmaceutical analysis
Karnataka college of pharmacy
Bangalore
02-Apr-2023
Presented to,
Dr.Harsha K.Tripathy,
Professor,
Dept. pharmaceutical analysis,
Karnataka college of pharmacy,
Bangalore.
FOOD ANALYSIS

Introduction
01
Types of milk
02
General analytical method for
milk
03
Adulterants and
contaminants of milk
04
Content
KARNATAKA COLLEGE OF PHARMACY 2

Introduction
 Milk is a white liquid food produced by the mammary gland of
mammals.
 It is the primary source of nutrition for young mammals before the
are able to digest solid food.
 Composition
water :87.3%
Fat :3.9%
Non fat solids :8.8%
1. Buffalo Milk : 7.44% (High Fat content)
2. Cow Milk : 3.66% (Low fat content)

Types of Milk
1. Standardized milk: Buffalo milk and skimmed milk (fat-4.5% and SNF is
8.5%).
2. Reduced fat milk : this milk contain 2% of milk fat.
3. Low fat milk (1%): 23% of its calories from fat.
4. Long life : milk pasteurized and homogenized and then kept at a high
temp for destroy bacteria (store for 1 week)
5. UHT (Ultra Heat Treatment): milk heated at high temperature (132/270
degree F) stored upto 3 months.

6. Dried milk : in powder form.
7. Evaporated: homogenized milk with considerably reduced water
content.
8. Condensed milk : simply evaporated milk to which sugar has been
added to thicken and sweeten it is mainly used for making desserts
and sweets.

12/5/2023 KARNATAKA COLLEGE OF PHARMACY 6
General analytical methods for
milk

1. Specificgravity (Lactometer)
 Specific gravity of milk means density of milk,
 Here, lactometer compare the milk with water to know the density of
milk.
 The specific gravity of milk varies according to the portion of fat and
SNF (Solid not Fat).
 The specific gravity of whole cow milk ranges from 1.028 – 1.034
gm/ml.

Procedure
 Adjust the temp milk sample at 15.5o C mix thoroughly.
 Add milk to jar and avoid incorporation of air.
 Pour the lactometer into the milk without touching sides of vessel
and term recorded.
S.G = Cal.lactometer reeding /1000 +1

2.PH
 In the milk we measure the PH due to presence of lactic acid.
 To determine the PH of the milk using PH meater.
 Milk PH is range from 6.6 – 6.8.
1. Reduced PH value – due to microbial activity
development of acidity,
1. High PH value – mastitis in animal
from which milk was obtained.

3.Determination of total solids
 Take a weight of crucible.
 Weigh 5g of milk in a crucible.
 Put a crucible in a water bath until dryness.
 After complete dryness put the crucible in an oven and weigh after cooling.
% of total solid = (wt.of crucible + sample) – After drying x 100.
Richmon’s formula for total solids:
T=0.25+1.22F+ 0.72
Where, D- Density, F- % Fat.

4. Determination of Chloride content
100 ml of milk + 40ml of water
Add 10 drops of pot.chromate
Titrate with 0.1 N AgNo3
Brick red precipitate
1ml of 0.1 N AgNo3 equivalent to 3.55 ug of chloride

5. Acidity of milk
10ml of milk + 1ml of
phenolphalein indicator
Titrate with 0.1N Sodium
Hydroxide
1ml 0.1N Sodium of Hydroxide = 0.009 g of Lactic acid
Normal range = 0.10 to 0.17 Lactic acid, excess cause acidity

6. Protein (Kjeldahl method)
Substance +
conc. H2So4 +
CuSO4 +
K2So4

1.Digestion:
The purpose of this step is to break down the bonds that hold the
polypeptides together, and convert them to simpler chemicals such as water,
carbon dioxide and ammonia.
General equation for the digestion of an organic sample is shown below
Protein + H2SO4 (NH2)SO4 + H2O +CO2
2. Distillation: (separation of ammonia from digestion mixture).
This is done by raising PH using NaOH this effects of changing the
ammonium(NH4) ions into Ammonia (NH3). Which indicates
(NH4)2SO4 + 2NaOH (0.1 N) NH4 +Hcl.
3.Titration : Than Hcl (0.1N) is titrated with std NaOH (0.1N)

7. Alcohol test
Mix equal volume of
milk with 68% of ethanol
In small bottle
If the tested milk is good quality
no- coagulation, clotting or
precipitation
68% = 68ml to make
up to 100ml by using
Distilled water

8. Clot on Boiling
Boil small amount of milk in spoon, test tube or other container.
If there is clotting, coagulation or precipitation fainted the test.
Heavy contamination in fresh drawn milk cannot detected
9. Organoleptic
 Judging the quality of milk by its taste and smell.
 Require skill and Practice.
10. Temperature
 Measure using thermometer.

1. Ice Creams
 Ice cream consists of basically of a mixture of milk, fat, sugar,
stabilizer, milk solids, flavor and color.
 Composition
total solids 32-40%
Fat 7-15%
Sugar 12-19%
Milk solids not fat 9-15%

1. Sugar – Lane eynon’s method
2. Fat – Gottelib method or gerber method or werner Schmid method.
3. Nitrogen – Kjeldhal method.
4. Butter fat:
Atleast 5% of milk + Heat ammonia
or alcohol just to boiling
Extraction with
solvent
Than solvent is removed by evaporation
and % of fat is determined

2.Milk powder/ Dried Milk
 Dried milk:
Automizing a spray of hot pre-condensed milk inside the large
chamber.
It meets hot air entering upto 190o C upto 260o C the milk dries
Instantaneously and falling powder is quickly removed.
Roller dried milk:
Running/Spraying of condensed milk on to revolving metal
rollers which are heated upto 150o C.
The milk is dries instantaneously on the ruller and the powder is
removed by scrapers and rapidly cooled.

3. Butter
 Butter is the product obtained by mixing the cream which are
separated from warm milk.
 Excess water is removed and the mass is rendered homogenous
usually with the addition of salt.
 Butter consists of butter fat, water, and curd which contain casein,
lactose and mineral material .
Fat : 80-84%
Water : 15.3 – 15.9%
Salt : 0.03 – 1.8%
NFMS : 1%

1. Total Solid Content (TSC).
2. Acidity.
3. Curd and Protein – Kjeldhar method.
4. Salt – transfer the curd + salt together with filter paper or crucible to
beaker containing hot water cool and titrate with 0.05M silver nitrate
(AgNo3) using potassium chromate as an indicator

4.Cheese
 Most types of cheese are made from curd produced from the
coagulation of souring of milk.
 Processed cheese is prepared from by heating a cheese and
emulsifying with water and salts such as sodium phosphate or
citrate or sodium potassium tartrate.
 Its composition is 39.9 – 43.2% water, 25.4-29.6% fat, 44.7-
49.3% fat in dry matter, 22.3-23.1% protein.
 Analysis of cheese: water, fat, ash, protein, acidity has been
discussed under various sections.

5.Margarine
 It is a butter substitute and contains 80% fat, 13- 15.7% water, 0.6 -1.5% salt
and 1% SNF (Solid not fat) and proportions of Vit A and Vit D.
 Fat, water, salt and SNF determination has been discussed under various
sections.
 Also Salt Determination.

ADULTERANTS AND
CONTAMINANTS OF MILK

1. Detection of cane sugar in Milk
(Modified seliwanoff method).
Principle : fructose + resorcinol in Hcl Red color.
Procedure :
 Milk + conc. Hcl stand for 10 minutes.
 filter
 1ml filtered milk serum and 5ml of modified resorcinol Hcl reagent.
 Water bath for exactly 1 mins.
 Withdraw the test tube and observe the Red colour

2.Detection of added urea in milk
(Higher fat content than before its appears thick)
 5ml of milk is mixed with 5ml of 1.6% of p- Dimethyl amino benzaldehyde
(PDAB) is added Distinct yellow colour observed in milk containing added urea.
 The control (Normal milk) shows a slight yellow colour due to presence of
natural urea.

3.Test for presence of hydrogen peroxide
(Adulterant for shelf life extension)
 Milk + Conc. Hcl (mix well)
 Drop of HCHO soln and Heat 60 degree celcius.
 Place starch iodine paper into solution.
 Oxidization of iodine
 Blue color.

4.Test for presence of Formaldehyde
To increase the shelf life for long distance transportation of milk without
refrigeration
 2ml milk in TT.
 2ml of 90 % H2SO4 which contain traces of FeCl3
 Purple color ring at junction
 Indicate Presence of Formaldehyde.

Milk analysis

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