Detecting Fraudulent or Adulterated Olive Oil

In brief. A fraudulent olive oil is blended with cheaper refined, pomace or seed oil, while being sold as extra virgin. Three purity markers give it away: stigmastadienes ≤ 0.05 mg/kg (trace of refined), waxes C42+C44+C46 ≤ 150 mg/kg (trace of pomace) and an abnormally high K270 (oxidation/refining). These analyses appear on a purity COA from an IOC-accredited laboratory.

Olive oil is one of the most frequently adulterated food products in the world. For an importer, acidity and the panel test are not enough: they measure quality, not purity. Here are the markers that reveal an adulterated oil and how to demand them.

What is a fraudulent olive oil?

A fraudulent olive oil is an oil whose composition does not match the label. The most common frauds consist of blending a genuine extra virgin (expensive) with a much cheaper oil: refined oil, pomace oil, seed oil (sunflower, rapeseed), or even deodorised refined lampante.

The aim is to sell at the extra virgin price a product that is not one. The problem: to the eye, the nose and sometimes even the taste, the fraud is undetectable. Only purity chemistry unmasks it.

The 3 purity markers to demand

Here are the three most revealing analyses, to demand on the COA in addition to the usual quality criteria.

Marker	What it detects	Threshold (extra virgin)
Stigmastadienes	Presence of refined oil	≤ 0.05 mg/kg
Waxes (C42+C44+C46)	Presence of pomace oil	≤ 150 mg/kg
K270 (UV absorbance)	Oxidation / trace of refined	≤ 0.22

• Stigmastadienes ≤ 0.05 mg/kg: these compounds form during refining. Above the threshold, the oil contains refined oil — so it is not a pure extra virgin.
• Waxes C42+C44+C46 ≤ 150 mg/kg: waxes are more abundant in solvent-extracted pomace oil. An exceedance signals a blend with pomace.
• K270: a high K270 often accompanies refining and advanced oxidation — a complementary warning signal.

Other purity analyses exist (sterol composition, fatty acids, ECN42 to detect seed oils), but these three are the first anti-blending reflexes.

How to protect yourself from fraud at purchase

Detection is not done at the mill or the bottle: it plays out on the documents and the process. Five reflexes:

1. Demand a per-lot purity COA, not just a quality one, from an IOC-accredited laboratory.
2. Systematically check stigmastadienes, waxes and K270 — not just acidity.
3. Keep a sealed reference sample of each lot to arbitrate a dispute.
4. Beware of an abnormally low price: at a genuine EVOO category with COA, prices tighten. A gap too good to be true often hides a blend.
5. Trace the origin: identified supplier, accreditation, history. The transparency of the quality process is the best anti-fraud barrier.

To cross-check all these values at once, enter the certificate in our quality classifier: it automatically applies both quality and purity thresholds.

FAQ — Olive oil fraud and adulteration

How do you know if an olive oil is pure?

Through a purity COA from an IOC-accredited laboratory, which checks in particular the stigmastadienes (≤ 0.05 mg/kg), the waxes (≤ 150 mg/kg) and the K270. These markers reveal a possible blend with refined or pomace oil, invisible to the taste.

What are stigmastadienes?

They are compounds that appear during the refining of the oil. In an extra virgin, they must stay ≤ 0.05 mg/kg. Beyond that, the oil contains refined oil: it is no longer a pure extra virgin.

What are the waxes used for in the analysis?

The waxes (C42+C44+C46) detect the presence of pomace oil (solvent-extracted), which is richer in waxes. A level > 150 mg/kg signals a blend with pomace in an oil declared as virgin.

Can fraud be detected by taste?

No, not reliably. A well-made blend is imperceptible to the palate. Only chemical purity analyses (stigmastadienes, waxes, sterols, fatty acids) can prove it.

Does a low price necessarily mean fraud?

Not always, but it is a warning signal. At a genuine EVOO category with a complete COA, origin prices resemble one another. A price well below the market often hides a lower category (refined, pomace) or a blend.

Which analyses should you request to avoid an adulterated oil?

At minimum: stigmastadienes, waxes and K270, in addition to acidity, peroxide and the panel test. To go further, add the sterol and fatty acid composition, which also detect seed oils.

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Do you want to avoid any bad surprise? Request a quote: each lot is delivered with a complete quality + purity COA (acidity, peroxide, K270, stigmastadienes, waxes) from an accredited laboratory, plus a sealed reference sample. Check an analysis with the quality classifier and decode each term in the glossary.