milk adulteration an overview.

1. By- Suvajit Majumdar

2. • It is an act of intentionally debasing the quality of the
milk either by the mixture or substitution of the inferior substances.
• ‘Adulterant’ means any material that make the food unsafe or
substandard or misbranded.
• Any material is added in the milk which reduces the nutritional value
of the milk as well as injurious to the health is called milk
adulteration.

3.  Food is declared adulterated if:
 A substance is added which has injurious affects or a substance
which donot pose any health issues but added in the milk for gaining
profit.
 Cheaper or inferior substances are substituted wholly or in part.
 Any valuable or necessary constituent has been wholly or in part
abstracted.
 It is coloured or otherwise treated, to improve its appearance or if it
contains any added substance injurious to health.
 For whatever reasons its quality is below the Standard.

4.  Food adulteration generally substitutes a cheaper component for the actual
ingredient, to save money.
 The main aim of addition of adulterants are to make profit –
 it can be added for increasing the shelf life.
 Or to gain maximum possible volume, so that the seller could get more money.
 Or to manage the Milk Fat and SNF as the pricing of milk is done by these two
parameters.
 Acc. to FSSAI the minimum Fat and SNF % of cow milk should be 3.0-4.0% and
8.5% respectively and for buffalo milk , for fat its 5.0-6.0% and SNF 9.0%.

5.  Adulterantions in milk mainly include addition of vegetable protein, milk from
different species, addition of whey and watering which are known as economically
motivated adulteration.These adulterations do not pose any severe health risk.
 Some adulterants are too harmful to be overlooked. Some of the major adulterants
in milk having serious adverse health effect are urea, formalin, detergents,
ammonium sulphate, boric acid, caustic soda, benzoic acid, salicylic acid,
hydrogen peroxide, sugars and melamine.

6. Sl. No. Adulterant Principle Procedure Observations
1. Cane sugar 1.Take 10 ml
milk in the test
tube.
2. Add 0.1 gm
resorcinol
powder and mix
the content
thoroughly.
3. Place the tube
in a boiling
water bath for 5
min. and observe
the colour.
1. Observe if
there is any
development of
red colour.
2. Development
of red colour
indicates that
canesugar is
added in milk.

7. Sl. No. Adulterant Principle Procedure Observation
2. Starch Add a few drops
of tincture of
Iodine or Iodine
solution.
Formation of
blue colour
indicates the
presence of
starch.
Iodine solution is
easily available
in the medical
stores
3. Detergent Take 5 ml of milk
in a test tube and
Add 0.1 ml of
bromocresol
purple solution.
Appearance of
violet color
indicates the
presence of
detergent in
milk.
Unadulterated
milk samples
show a faint
violet color.

8. Sl.No. Adulterants Principle Procedure Observation
4. Urea Urea content in
natural milk varies
from 20 mg/100 ml
to 70 mg/100 ml.
However, urea
content above 70
mg/100 ml in milk
indicates milk
containing ‘added
urea’.
Mix 1 ml of milk
with 1 ml of 1.6%
DMAB reagent.
Observe the color.
Distinct yellow
colour is observed
in milk containing
added urea.The
control (normal
milk) shows a slight
yellow colour due to
presence of natural
urea.

9. Sl.
No
Adulterant Principle Procedure Observation
Formalin Formalin enhances
the life of milk and
thus is added for
preservation
purpose.
Take 10 ml of milk in a test
tube and add 5 ml of
concentrated Sulphuric acid
from the sides of the wall
without shaking.
If a violet or blue ring appears at the
intersection of two layers then it
shows presence of formalin
Ammonium
Compound
Take 1 ml of milk in a test tube
and
Add 0.5ml o 2% sodium
hydroxide solution,
0.5ml of 2% sodium
hydroxide solution and
0.5ml 5% phenol solution.
Heat for 20 sec. in boiling
water bath.
A blush color immediately forms,
which turns deep blue in case of a
sample containing ammonium
sulphate.
The color remains stable for 12hrs,
the development of pink color
shows that the sample is free from
ammonium sulphate.

10. Sl.No. Adulterants Principle Procedure Observation
Hydrogen Peroxide Take 5 ml milk in a
test tube. Add 3
drops of
Paraphenylene
Diamine and shake
well.
Change in colour of
the milk to blue
confirms that the
milk is adulterated
with Hydrogen
Peroxide.
Water The presence of
water can be
detected by putting a
drop of milk on a
polished slanting
surface.
The drop of pure
milk flows slowly
leaving a white trail
behind it, whereas
milk adulterated with
water will flow
immediately without
leaving a mark.

11. Sl.no. Adulterant Principle Procedure Observation
Pond
Water/Nitrates
Pond water is
heavier than the tap
water , some
unscrupulous
persons for
adulteration in milk
usually prefer it.
Take 2 ml of milk in
a test tube.
Rinse the tube with
the milk and drain
the milk from the
test tube.
Add two-three
drops of the
Diphenylamine
(2%,w/v in
sulphuric acid
reagent) along the
side of the test
tube.
Note the
developed colour.
Deep blue color
will be formed in
presence of nitrate
in the milk sample.
Pure milk sample
will not develop
any color.

12. BORIC ACID /
BORAX
Five ml of milk is
taken in a test tube
Add 1 ml of
concentrated
hydrochloric acid
is added and
mixed well.
Tio of a turmeric
paper is dipped
into the acidified
milk
It is dried in a
watch glass at
100°C or over a
small flame.
If the turmeric
paper turns to red,
it indicates the
presence of borax
or boric acid.
Confirmation can
be made by
adding a drop of
ammonia solution
on turmeric paper
and if the red color
changes to green,
it shows the
presence of boric

13. Sl.no. Adulterants Principle Proceduer Observation
Benzoic acid
ans Salicylic
acid
Five ml of milk is
taken in a test
tube and
Acidified with
concentrated
sulphuric acid.
0.5% ferric
chloride solution
is added drop by
drop and mixed
well.
Development of
buff color
indicates
presence of
benzoic acid
Development of
violet color
indicates salicylic
acid.
Removal of Fat The Lactometer
reading will go
above 26.

14. Sl. No. Adulterant Principle Procedure Procedure
Neutrilizers In milk
neutrilizers like
hydrated lime,
sodium hydroxide
sodium carbonate
or sodium
bicarbonate are
added which are
generally
prohibited.
Take 2 ml of milk
in a test tube and
Add 2 ml (95%)
alcohol
Add 2 drops of
rosalic acid
If the color of milk
changes to pinkish
red, then it is
inferred that the
milk is adulterated
with sodium
carbonate /
sodium
bicarbonate.

15. Sl.no. Adulterant Principle Procedure Observation
Sulphates Take 5 ml of
milk sample in
a test tube. Add
1 ml of
Nessler’s
reagent. Mix the
contents of the
tube
thoroughly.
Observe and note the color.The
control milk sample gives slight
grayish colour. At low
concentration of ammonium
compounds, brownish shade
appears which is distinguishable
at 0.15% followed by yellowish
colour and then orange colour
development at higher
concentration.The limit of
detection of method is 0.15%.

16.  Fssai manual for milk and milk products
 Dairy science.org.in