There are many ways to check the purity of mustard oil, but the main indicator is usually the aroma. Pure mustard oil has a pungent aroma that you can smell when you open the bottle. Another way to be sure of the purity of mustard oil is to bring home only FSSAI-approved oil such as Fortune Kachi Ghani Mustard oil, which is made with 100% sarso and is free of any adulterants.