Detection of Starch in Milk :
Requirements (Instruments, Chemicals & Other) :

1. Milk sample
   
2. Test tubes
   
3. Water bath
   
4. Measuring cylinder
   
5. Iodine solution
   

Procedure :

1. Take 5 ml of milk from both the sample A and B in separate test tubes.
   
2. Place both the test tubes in the water bath maintained at boiling temperature.
   
3. Remove the test tubes from water bath and allow it at room temperature or 5 min.
   
4. Add 1-2 drops of iodine solution to both the test tubes.
   
5. Observe the color change in both the test tube.
   
6. Development of blue colour indicates presence of starch.
   

Detection of added urea in the milk :
Requirements (Instruments, Chemicals & Other) :

1. Milk sample
   
2. Test tubes
   
3. Pipette
   
4. DMAB reagent (1.6%, w/v)
   

Procedure :

1. Take 1 ml of milk from both the sample A and B in separate test tubes.
   
2. Add 1 ml of 1.6% DMAB reagent in both the test tube.
   
3. Observe the color change in both the test tube.
   
4. Appearance of distinct yellow color in milk sample shows the urea adulteration.
   

Test for presence of detergent in the milk :
Requirements (Instruments, Chemicals & Other) :

1. Milk sample
   
2. Test tubes
   
3. Pipette
   
4. Methylene blue dye
   
5. Chloroform
   

Procedure :

1. Take 1 ml of milk from both the sample A and B in separate test tubes.
   
2. Add 1 ml of Methylene blue dye solution followed by addition of 2 ml chloroform in both the test tubes.
   
3. Vortex the contents for about 15 sec and centrifuge at about 1100 rpm for 3 min.
   
4. Observe the intensity of blue color in lower and upper layer.
   
5. Relatively, more intense blue color in lower layer indicates presence of detergent in milk. Relatively more intense blue color in upper layer indicates absence of detergent in milk.