Indicative only, not a lab test
Home checks below can raise suspicion but cannot confirm adulteration. For a conclusive result, use an accredited laboratory — see food testing.
Common adulterants
- Mashed potato, sweet potato and other starches — Added as cheap bulk; not a permitted ingredient in ghee or butter.
Warning signs
- Grainy or unusually pasty texture
- Blue colour when a few drops of iodine are added (starch)
- Unusually low price for the quantity
Home checks
- Starch in ghee or butter: Put half a teaspoon of ghee or butter in a transparent glass bowl and add 2 to 3 drops of tincture of iodine. A blue colour indicates starch such as mashed potato or sweet potato. (Indicative only. A household test can give a false positive or false negative, and it cannot tell you the amount present or whether the food meets the legal standard. Only testing by an accredited laboratory confirms adulteration. This test detects only starch; it says nothing about vegetable fat or other animal fat blended into ghee.)
Laboratory testing
To confirm adulteration, a sample must be analysed by a food testing laboratory using standard methods. A purchaser can have food analysed by a Food Analyst for a fee under section 40 of the Food Safety and Standards Act, 2006, but must tell the seller at the time of purchase; you can also report to the food safety authority, whose officers draw official samples. See the Food testing page for official lab directories. Blending with other fats cannot be ruled out by the iodine test; this needs laboratory analysis.