K232, K270, ΔK: Olive Oil Oxidation Indices

In brief. K232, K270 and ΔK are ultraviolet absorbances that reveal the oxidation state and any refining of an olive oil. For an extra virgin, the limits are K232 ≤ 2.50, K270 ≤ 0.22 and ΔK ≤ 0.01. A high K270 betrays advanced oxidation or a trace of refined oil.

On a certificate of analysis (COA), after acidity and peroxide, these three UV indices complete the quality diagnosis. Here is what they measure and how to interpret them.

What each index measures

Index	What it reveals	Extra virgin limit
K232	Primary oxidation (initial products)	≤ 2.50
K270 (K268)	Secondary oxidation / trace of refining	≤ 0.22
ΔK (delta-K)	Deviation revealing abnormal treatment	≤ 0.01

• K232 rises when the oil begins to oxidise (poor storage, damaged fruit).
• K270 rises later in oxidation, or in the presence of refined oil: it is a key marker for detecting blending fraud.
• ΔK is calculated from several wavelengths; a ΔK beyond the limit signals abnormal treatment.

Why it matters when buying

An oil can show perfect acidity and yet present borderline UV indices: a sign that it has aged or undergone treatment. For an importer, checking K232/K270/ΔK at a given category avoids buying an extra virgin "on paper" but oxidised in reality.

Practical point

In the IOC standard, K232 is an optional commercial criterion; it is required in the EU. So make sure the COA provides it if your market is European. Our quality classifier applies all these limits automatically from the certificate's values.

FAQ

What does K270 mean on an olive oil?

K270 (sometimes noted K268) measures secondary oxidation and reveals any trace of refined oil. For an extra virgin, it must stay ≤ 0.22.

What is the difference between K232 and K270?

K232 captures primary oxidation (start of the process), K270 secondary oxidation and refining. Together they position the oil on the oxidation curve.

What is ΔK?

Delta-K is a calculation combining several UV absorbances; beyond the limit (> 0.01 for EVOO), it signals abnormal treatment or adulteration.

Can an oil have good acidity but bad K values?

Yes. Acidity and the UV indices measure different things. A well-pressed but poorly-stored oil can see its K270/K232 climb while acidity stays low.

Is K232 mandatory?

In the EU, yes. In the IOC standard, it is an optional commercial criterion. For an export to Europe, demand it on the COA.

How to check these indices easily?

By entering the COA values into a classifier that applies the IOC/EU limits — it immediately indicates whether the oil holds the stated category.

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