MILK ADULTERATION

By, Gautami Shirsat Grisha Dialani

Sushmita Suman

CONSUMER SURVEY � Average consumption per day – 1 lit. � Type of consumption – Directly as milk or

in tea � Mostly preferred – Buffalo Milk � Consumers don’t trust the milk vendor

completely but are left with no choice. � Need for a handy device to check the

adulteration.

Katraj Dairy Visit

NEED FOR PROJECT �  ‘Over 68% of milk does not meet Food

Safety Standards in India’-foodsafetyhelpline.com(March 18,2016)

�  ‘Milk adulteration should amounts to life imprisonment’-vakilno1.com(December 5,2013)

�  ‘1253 milk adulteration cases had been registered in the city(Mumbai) during 2015-16 and 55 people had been arrested’-Times Of India(July 2016)

MILK ADULTERANTS � Water �  Starch � Urea � Detergent � Glucose/Invert sugar � Vanaspati �  Formalin � Hydrogen Peroxide �  Sodium bicarbonate

Chromatography

� Principle : Differential affinities (strength of adhesion) of the various components of the analyte towards the stationary and mobile phase results in the differential separation of the components.

� The components that adhere more strongly to the stationary phase travel more slowly as compared to the components with weaker adhesion.

THIN LAYER CHROMATOGRAPHY (TLC) � TLC is a simple, quick, sensitive and

inexpensive procedure that gives a quick answer as to how many components are in a mixture.

� Developed by Ismailoff and Schraiber in 1938.

� An adsorbent is coated on a glass plate which serves as a stationary support on which the mobile phase percolates and develops the chromatogram.

RUNNING OF A TLC PLATE *All experimental work and testing was performed at room temperature.

Preparation of milk samples

Preparation of mobile phase

Preparation of TLC plate

Spotting the TLC plate

Development of the plate

Visualization of the spots

STEP 1 – SELECTION OF MOBILE PHASE

�  Pure hexane � Hexane + Acetone (9:1) � Hexane + Acetone (8.5:1.5) � Hexane +Acetone (8:2) �  Toluene + Ethyl Acetate (8.5:1.5) �  Pure Water � Water + Acetone (few drops) �  Petroleum ether +Acetone (8.5:1.5) � Hexane + ethyl acetate (8.5:1.5) �  Petroleum ether + ethyl acetate (8.5:1.5)

STEP 2 – STATIONARY PHASE

� TLC plates coated with silica gel were used.

� A line 0.5cm from the bottom was drawn for the deposition of a spot of the analyte.

� Another line 3cm from the bottom was drawn for the solvent run.

STEP 3 - SPOTTING

� Preparation of very fine capillary tubes. � The plate was spotted with a drop of

different samples.

STEP 4 – RUNNING OF THE TLC

� The plate was placed vertically in the solvent beaker and allowed to run upto a distance of 3cm.

STEP 5 – DEVELOPMENT OF CHROMATOGRAM

� The chromatogram was placed in an iodine chamber for development of spots.

STEP 6 – VISUALIZATION OF SPOTS

�  Spots for different samples were observed.

STEP 7 – CALCULATION OF Rf

� The retention factor, or Rf, is defined as the distance travelled by the compound divided by the distance travelled by the solvent.

Rf= 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑡𝑟𝑎𝑣𝑒𝑙𝑙𝑒𝑑 𝑏𝑦 𝑠𝑜𝑙𝑢𝑡𝑒/𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑡𝑟𝑎𝑣𝑒𝑙𝑙𝑒𝑑 𝑏𝑦 𝑠𝑜𝑙𝑣𝑒𝑛𝑡 𝑓𝑟𝑜𝑛𝑡 

OBSERVATION TABLE (Solvent : petroleum ether and ethyl acetate) SAMPLE SOLUTE

RUN (cm) SOLVENT

FRONT (cm)

Rf

Urea 1.8 2.5 0.72

NaHCO3 2.2 2.5

0.88

Pure Milk - 2.5

-

Milk + Urea ~1.8 2.5

~0.72

Milk + NaHCO3 ~2.2 2.5

~0.88

Milk + Urea + NaHCO3

~1.8 , ~2.2 2.5

~0.72 ,~ 0.88

CONCLUSION � Using petroleum ether and ethyl acetate in

the proportion of 8.5:1.5, it is possible to detect adulterants such as urea and sodium bicarbonate in milk.

� Also, it was observed that when a drop of milk containing starch was tested, the spot turned dark violet after development.

� On further research, it is possible to come up with a suitable solvent which could be used as a mobile phase for detection of most of the adulterants in the milk sample.

WHY SHOULD INDUSTRIES THINK OVER OUR TECHNIQUE?

�  Small, sensitive and easy to handle � Cost efficient � Time efficient � No skilled labor

Prototype:

REFERENCES :

�  Food Science by B. Srilakshmi (Third edition, 2003)

�  Food Science-Norman N. Potter, Joseph H. Hotchkiss

� Basic Concepts of Analytical Chemistry – S. M. Khopkar (Third edition – 2008)

�  Fundamentals of Analytical Chemistry – Skoog Douglas (Ninth edition - 2013)