Cooking oil adulteration is one of the most persistent food safety problems in India. Cheaper oils get blended into more expensive ones, refined oil gets sold as cold pressed, and colour gets added to imitate what refining removed.
You cannot replicate a laboratory at home. But these five checks will tell you more than the label does.
1. The refrigerator test
Pour a little oil into a clear glass and refrigerate for two hours.
- Pure coconut oil solidifies uniformly and turns solid white.
- Adulterated coconut oil separates into layers — the coconut fraction sets while the blended oil stays liquid on top.
- Groundnut, sesame and sunflower oil thicken slightly but should stay clear and uniform, not layered.
Layer separation is the clearest home signal of blending.
2. The colour check
Hold the bottle against daylight. Unrefined oil carries the colour of the seed:
- Groundnut — warm amber
- Mustard — deep gold
- Sesame — rich brown-gold
- Niger — dark, almost coffee-toned
- Coconut — clear, going solid white when cool
Pale, watery oil sold as cold pressed has usually been refined. Be equally wary of colour that looks unnaturally vivid — synthetic dye is a known adulterant, particularly in mustard oil.
3. The smell test
This is the fastest one. Open the bottle and inhale.
Unrefined oil smells strongly of its seed. Mustard should catch slightly at the back of your nose. Sesame should smell toasted and nutty. If the oil smells of almost nothing, it has been deodorised at high heat — which means it is refined, whatever the front label says.
4. The palm rub test
Put a few drops on your palm and rub. Pure cold pressed oil absorbs reasonably into the skin and leaves a clean scent. Adulterated or heavily refined oil tends to sit on the surface feeling greasy, and the smell fades almost immediately.
This test works particularly well for coconut oil and castor oil.
5. Check the paperwork
The least dramatic test and the most reliable one.
- FSSAI licence number printed on the label. Ours is 1122632300006. You can verify any licence on the FSSAI FoSCoS portal.
- Packing date and batch number. Cold pressed oil is perishable. A producer confident in freshness dates the bottle.
- Single-source declaration. "Blended vegetable oil" means exactly that.
Storing oil so it stays good
Even genuinely pure oil goes rancid if stored badly. Keep it in a cool, dark cupboard away from the stove. Heat and sunlight are what turn good oil bad. Close the cap properly — oxygen drives oxidation. Buy sizes you will finish in three to six months.
Frequently asked questions
How can I tell if coconut oil is pure at home?
Refrigerate it for two hours. Pure coconut oil solidifies uniformly into a white solid. If it separates into a set layer and a liquid layer, another oil has been blended in.
Does pure cold pressed oil have sediment?
Yes, and a small amount is a good sign. Unrefined oil is not industrially filtered, so fine seed particles settle at the bottom over time.
Is cloudy oil spoiled?
Usually not. Cloudiness in cold weather is normal for unrefined oil, and coconut oil solidifies below about 24°C. Rancidity announces itself by smell — sharp, stale, paint-like — not by cloudiness.
How do I verify an FSSAI licence number?
Enter it on the FSSAI FoSCoS portal. It will show the registered business name and the licence status. If a bottle has no FSSAI number at all, do not buy it.
Every Chennamma Ajji oil is pressed in small batches and FSSAI certified under licence 1122632300006. See what we make.