Adulterant: Water, Starch, Urea, synthetic milk, vanaspathi, detergent, formalin
How do you find out?
Water: Run a drop of milk on a slope surface. Water added milk will run fast on the slope not leaving white mark behind. Whereas pure milk runs slowly leaving white thread mark behind
Starch: Add few drops of iodine or tincture to milk, if milk changes to blue color starch is added.
Urea: Add 1/2 teaspoon of soybean powder to milk in a test tube and mix it. After 5 minutes, dip a litmus paper in the mix. If the color changes from red to blue then the milk is adulterated with urea.
Formalin: Take 10 ml of milk and slowly from the inner side of the test tube add 5 ml of conc. Sulphuric acid**. If a blue ring forms in the center of the intersection of two liquids then there is formalin adulteration.
** Be careful while handling sulphuric acid as it is dangerous. You can take milk sample to local colleges and labs seeking help for this test.