Platform tests for milk

Platform tests for milk to assure quality and safe access of milk to the plant

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

8. 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 2/3 rd 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.

9. 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