Adulteration of cooking oil is a common practice aimed at increasing profits by diluting or altering the oil with cheaper or lower-quality substances. Detecting adulteration in cooking oil can be challenging, but there are a few methods you can use at home to spot potential issues.

Clarity

Pure cooking oil is usually clear. If the oil appears cloudy or has sediment at the bottom, it may be adulterated.

Refrigeration test

Place the oil in the refrigerator for a few hours. Pure coconut or olive oil will solidify at lower temperatures, while adulterated oils might remain liquid or partially solidify.

Burning test

Heat a small amount of oil in a pan. Pure oil has a typical aroma when heated, but adulterated oil may emit an unusual or unpleasant odour.

Blotting paper test

Place a few drops of oil on blotting paper or a plain white sheet of paper. Pure oil will spread uniformly without leaving any residues. Adulterated oil may leave stains or traces of other substances.

Soap test (for coconut oil)

Mix 2 ml of coconut oil with 2 ml of caustic soda (sodium hydroxide) solution and 1 ml of water. If the oil turns into a soap-like paste, it's pure. Adulterated oil may not form a proper paste.