How to read an olive oil certificate of analysis (COA)

In brief. An olive oil certificate of analysis (COA) summarizes the measurements of a lot: free acidity, peroxide value, K232, K270, ΔK, ethyl esters, polyphenols and often the sensory panel. For an extra virgin (EVOO), the key thresholds are: acidity ≤ 0.8%, peroxide ≤ 20 mEq O₂/kg, K232 ≤ 2.50, K270 ≤ 0.22, ΔK ≤ 0.01. A COA is only valid for export if it comes from an IOC-accredited laboratory and concerns the delivered lot.

The COA is the document that proves the real category of the oil you are buying. Knowing how to read it line by line means avoiding downgrades, disputes and unpleasant surprises on arrival. Here is how to decrypt it.

What is an olive oil COA?

The certificate of analysis (COA), also called analysis report, is the laboratory report that attests to the chemical and sensory characteristics of a specific lot of oil. It serves as a contractual reference between seller and buyer: it is what confirms that an oil is indeed "extra virgin" and not a mere commercial declaration.

For Tunisian export, the analysis per lot is carried out under the control of the ONH (National Oil Office) in a laboratory accredited by the International Olive Council. A valid COA must always indicate the lot number, the analysis date and the issuing laboratory.

The COA lines, one by one

Here are the parameters you will find on a serious COA, and what each means.

Parameter	What it measures	EVOO threshold (IOC/EU)
Free acidity (% oleic acid)	Fruit degradation / freshness	≤ 0.80%
Peroxide value (mEq O₂/kg)	Primary oxidation	≤ 20
K232	Primary oxidation (UV)	≤ 2.50
K270	Secondary oxidation / refining (UV)	≤ 0.22
ΔK (Delta-K)	Trace of refining	≤ 0.01
Ethyl esters (FAEE)	Fermentation of olives	≤ 35 mg/kg
Sensory panel	Defects (Md) / fruitiness (Mf)	Md = 0 · Mf > 0
Polyphenols (mg/kg)	Antioxidants / health claim	≥ 250 = EFSA claim

Each value of the lot must fall within the limits of the targeted category. A single out-of-threshold parameter downgrades the oil.

Acidity and peroxide: freshness

Free acidity (≤ 0.8% for EVOO) measures free fatty acids, a sign of fruit degradation. The peroxide value (≤ 20 mEq O₂/kg) measures primary oxidation. Together, they tell whether the oil is fresh and well extracted. Very low values (acidity ≤ 0.4%, peroxide ≤ 10) are an excellent sign.

K232, K270 and ΔK: oxidation and refining

These UV absorbances detect advanced oxidation and traces of refining. K232 ≤ 2.50 targets primary oxidation; K270 ≤ 0.22 secondary oxidation; ΔK ≤ 0.01 reveals a blend with refined oil. An abnormally high K270 is a major warning sign (see our glossary for the detail).

Polyphenols: the health argument

Polyphenols (hydroxytyrosol and derivatives) are not a category criterion, but a value argument. At ≥ 250 mg/kg, the oil is eligible for the EFSA health claim (EU Reg. 432/2012). Tunisian oils of the Chetoui variety often exceed this threshold.

The sensory panel

Official classification as extra virgin requires an accredited tasting panel: median of defects (Md = 0) and median of fruitiness (Mf > 0). Without a compliant panel, a chemically clean oil cannot be officially classified as EVOO.

The 5 pitfalls to spot on a COA

1. Generic COA (not linked to a lot number). Without a lot, it proves nothing about the delivered goods.
2. Expired COA. An analysis several months old no longer reflects the current state of the oil.
3. Laboratory not IOC-accredited. For export, only an accredited lab is authoritative.
4. Missing panel. The EVOO classification is not complete without a sensory evaluation.
5. A parameter "just under the threshold". An acidity at 0.79% or a K270 at 0.21 leaves little margin for transport.

To cross-check all these figures automatically, enter them in our COA quality classifier: it tells you the official category of the lot.

The right reflex: COA + reference sample

A COA is always paired with a sealed reference sample, kept on both sides. In case of a dispute on arrival, the delivered oil is compared with this sample and with the original COA. This double security is part of a serious quality process and avoids most disputes.

FAQ — Reading an olive oil COA

What is an olive oil COA?

A certificate of analysis is the laboratory report that attests to the characteristics of a lot of oil: acidity, peroxide, UV indices, esters, polyphenols and sensory panel. It confirms the official category (extra virgin, virgin…) and serves as a contractual reference between seller and buyer.

What are the key parameters of a COA?

The essential parameters are free acidity, peroxide value, UV absorbances (K232, K270, ΔK), ethyl esters, polyphenols and the sensory panel (defects / fruitiness). Each must remain within the thresholds of the targeted category.

What thresholds for an extra virgin on a COA?

For an EVOO: acidity ≤ 0.8%, peroxide ≤ 20 mEq O₂/kg, K232 ≤ 2.50, K270 ≤ 0.22, ΔK ≤ 0.01, ethyl esters ≤ 35 mg/kg, panel with zero defects (Md = 0) and positive fruitiness (Mf > 0). IOC/EU thresholds, to be verified.

Is a COA enough to guarantee quality?

It is necessary but not sufficient. A valid COA must relate to the delivered lot, be recent and come from an IOC-accredited laboratory. It is complemented by a sealed reference sample to compare on arrival in case of a dispute.

Who must issue the COA for export?

An IOC-accredited laboratory. In Tunisia, the analysis per lot is carried out under the control of the ONH. A COA issued by a non-accredited laboratory or a mere declaration by the seller has no evidential value for export.

What to do if a parameter exceeds the threshold?

A single out-of-limit parameter downgrades the oil into a lower category (for example from extra virgin to virgin, or to lampante). The price must be renegotiated at the real category of the lot, never pay an EVOO price for a downgraded oil.

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Want a complete COA before buying? Request a quote: each lot is delivered with its certificate of analysis from an accredited laboratory and a reference sample. To test your own figures, use the quality classifier.