This document describes several platform tests used to examine milk quality at reception docks for acceptance or rejection. The tests include organoleptic evaluation of odor, appearance, color and consistency. The clot on boiling test examines milk stability at heat processing. The alcohol test detects abnormal mastitic milk. The two-minute resazurin test determines bacterial quality by comparing color change to a standard. The sediment test examines visible dirt. Specific gravity is tested using a lactometer to detect water adulteration. Other tests include methylene blue reduction and fat content estimation. Interpretations for cow and buffalo milk specific gravities are provided.

1. DEPARTMENT OF LIVESTOCK
PRODUCTS TECHNOLOGY
RANCHI VETERINARY COLLEGE
BIRSA AGRICULTURAL UNIVERSITY,
KANKE
BY :- ANAL BOSE, 3rd Year

2. PLATFORM TESTS
 OBJECTIVES
 For examination of milk by adopting rapid tests for
acceptance/rejection of milk at reception dock. Rapid quality
control tests.
 Organoleptic evaluation
 Clot on boiling test (COB)
 Alcohol test
 Resazurin test
 Sediment test

3. ORGANOLEPTIC EVALUATION
 Odour/ Smell
 General Appearance
 Colour
 Consistency
 Temperature

4. CLOT ON BOILING TEST
 OBJECTIVES
TO DETERMINE THE STABILITY OF MILK FOR HEAT
PROCESSING (INCREASED ACIDITY)
 Take 5ml of milk in the test tube.
 Put this on boiling water bath for 5min.
 Remove the tube from water bath without shaking.
 Note any acid smell or precipitated particles on the side of the test
tube.
Sample showing precipitated particles are recorded as positive COB test.
Such milk is rejected on the platform.

5. ALCOHOL TEST
 OBJECTIVES
TO DETECT ABNORMAL MILK SUCH AS MASTITIC MILK.
(BASED ON FACT THAT MILK PROTEIN SOURED AS RESULT OF LACTIC ACID
PRODUCED BY BACTERIA BECOMES SUSCEPTIBLE TO ALCOHOL)
 Take 5ml of milk in the test tube.
 Add equal quantity of 68% Ethyl Alcohol.
 Mix the content of the test tube by inverting several times.
 Examine the tube and note any coagulation.
If coagulation has occurred, fine particles of curd will be visible on the
inside of surface, presence of flakes denotes positive. Such samples are
rejected.

6. TWO MINUTES RESAZURIN TEST
 OBJECTIVES
TO DETERMINE THE EXTENT OF BACTERIOLOGICAL
QUALITY OF MILK.
 Mix the sample thoroughly by inverting from one test tube to other.
 Pour 10ml of milk sample in to a sterilized test tube.
 Add quickly 1ml of Resazurin solution in the test tube.
 Mix the milk and dye thoroughly by inverting the tube 2-3 times.
 Place the tube in the water bath at temp. 37.5 degrees only for 2 mins.
 Take our the tube from the water bath.
 Compare the colour of test tube with standard disc until the colour
matches with the comparator.
 Record the value of disc/colour. If colour falls between two disc
numbers, record half value.

7. SEDIMENT TEST
 OBJECTIVES
TO KNOW THE EXTENT OF VISIBLE DIRT PRESENT IN
THE MILK AS A MARK OF CLEAN MILK PRODUCTION.
 Take a milk sample from a well stirred can of milk with the help of
sampling dipper.
 Filter the milk through properly adjusted firm link disc held in the
sediment tester, so that the filteration area of 28 mm diameter is
exposed.
 Remove the cotton disc from sediment tester after filteration.
 Compare the lintine cotton disc with the standard disc.

9. TEST FOR SPECIFIC GRAVITY (LACTOMETER)
OF MILK
 OBJECTIVES
TO DETERMINE THE NATURE OF ADULTERATION OF
MILK. (ADDED WATER).
 Adjust the temperature of milk to room temperature. (25 degree
Celsius avg.)
 Fill the clean glass jar about 2/3rd volume by milk, pour the milk
down along the sides of the jar to avoid incorporation of air.
 Lower the lactometer gently in the milk making sure the lactometer
floats freely without touching sides of the jar.
 Read the lactometer reading (LR) at the top of meniscus within 1
min.
 Record the temperature of milk.

10. Other platform tests:-
• Methylene Blue reduction test.
• Fat estimation (gerber’s method by butyrometer)
• Direct microscopic count
Interpretations :
Cow milk – 1.028 - 1.030
Buffalo milk – 1.030 – 1.032