Edible oil and fat testing
Oil testing answers three separate questions: is the oil what it claims to be, has it gone rancid, and is it adulterated. Identity comes from iodine and saponification values and the fatty acid profile; degradation from free fatty acid and peroxide value; adulteration from specific tests for argemone and mineral oil.
Parameters and what they reveal
Specific limits vary by oil type under the food safety regulations — mustard, groundnut, sunflower and palm each have their own identity ranges. We report against the standard for the oil you declare.
| Parameter | Tells you | Matters most for |
|---|---|---|
| Free fatty acid (FFA) | How far the oil has broken down | Frying oil reuse, storage life |
| Peroxide value | Onset of oxidative rancidity | Stored and packed oils |
| Iodine value | Degree of unsaturation — an identity marker | Detecting substitution |
| Saponification value | Average fatty acid chain length | Identity confirmation |
| Refractive index | Quick identity screen | Incoming material check |
| Moisture and volatile matter | Hydrolytic spoilage risk | Bulk storage |
| Unsaponifiable matter | Mineral oil and non-fat contamination | Adulteration |
| Argemone oil test | A specific, dangerous mustard oil adulterant | Mustard oil |
| Mineral oil test | Petroleum-derived adulteration | Any edible oil |
| Fatty acid profile | Definitive identity and blending detection | Substitution and blend claims |
What to send us
Frying oil: when to discard
Most commercial kitchens judge frying oil by colour, which lags the chemistry badly. Free fatty acid and polar compound content rise long before oil looks dark, and reheated oil past that point carries a genuine health issue as well as a taste one. If you run a kitchen at volume, testing oil from the same fryer at a few known reuse counts gives you a discard rule based on your own oil and your own process rather than a guess.
Questions about this test
Is my mustard oil adulterated?
The argemone test is specific and important — argemone oil adulteration causes serious illness and has driven outbreaks in eastern India. Combine it with the fatty acid profile if you also want to know whether cheaper oils have been blended in.
How often should a sweet shop test its oil?
Test the incoming oil for identity and initial quality, then set a reuse rule from a one-off FFA study of your own fryers. After that a periodic spot check is enough to confirm the rule is being followed.
Can you tell blended oil from pure?
Usually yes. The fatty acid profile of a blend rarely matches the declared single oil, and iodine value plus refractive index often flag it before the profile confirms it.