Cooking oils

Common adulterants

• Other (cheaper) oils mixed into coconut oil — Misrepresents what you are buying.
• TOCP (tri-ortho-cresyl phosphate) — Named by DART as a contaminant in oils and fats; a chemical that must not be present in food.

Warning signs

• Coconut oil that, after 30 minutes in a refrigerator (not freezer), shows a separate liquid layer
• Oil sold as 'refined winterised salad oil' that is not clear after chilling

Home checks

• Other oils in coconut oil: Put coconut oil in a transparent glass and place it in a refrigerator (not the freezer) for 30 minutes. Pure coconut oil solidifies; if it has been mixed with another oil, the other oil stays as a separate layer. (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. The result depends on your fridge temperature and the oil's grade.)
• TOCP in oils and fats: DART describes mixing 2 ml of the oil with a little solid yellow butter; an immediate red colour is said to indicate TOCP. (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. Because TOCP is a hazardous chemical, do not repeat this at home if you suspect poisoning; contact the authorities and a doctor instead.)

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.