How to Read an Olive Oil Lab Report

The short answer: An olive oil lab report boils down to five things — free acidity, peroxide value, UV absorbance, polyphenols, and a taste panel. Each one answers a different question: how carefully the fruit was handled, how fresh the oil is, and whether it actually earned the words "extra virgin". Here's what each line means, and what good looks like.

Most olive oil brands never show you a lab report. The oil gets tested — it has to be, to be sold as extra virgin — but the paperwork stays between the producer and the regulator. So when a brand does publish one, it helps to know what you're looking at. Five lines do most of the talking.

Free acidity: how carefully was the fruit handled?

Free acidity measures the breakdown of the oil's fat molecules, expressed as a percentage. It rises when olives are bruised, overripe, or left sitting around before pressing — so it's really a measure of care, from tree to press.

• ≤ 0.8% — the legal ceiling for extra virgin.
• ≤ 0.5% — good.
• ≤ 0.3% — excellent; healthy fruit, pressed fast.

The best early-harvest oils often land around 0.1–0.2%. One thing acidity is not: a taste. You can't taste acidity in olive oil — it's a chemical marker, not a flavour of sharpness.

Peroxide value: how fresh is it right now?

Peroxide value measures early-stage oxidation — the oil's reaction with oxygen — in milliequivalents of oxygen per kilo (meq O₂/kg). It creeps up with age, heat, and exposure to air and light.

• ≤ 20 meq O₂/kg — the legal ceiling for extra virgin.
• ≤ 10 — good.
• Single digits — what a fresh, well-kept oil looks like.

A low peroxide value at bottling is only half the story, though — the number keeps moving after the oil leaves the mill, which is why how the oil is packed and stored matters so much.

UV K-values: has it been aged, refined, or cut?

The K-values (K232, K268 or K270, and Delta-K) measure how the oil absorbs ultraviolet light. Oxidised or refined oils absorb UV differently from fresh, cold-pressed juice — so these numbers can catch an oil that's older than it claims, or quietly blended with refined oil.

• K232 ≤ 2.50 — early oxidation check.
• K270 ≤ 0.22 — later oxidation and refining check.
• Delta-K ≤ 0.01 — the fingerprint check for refined oil in the mix.

You don't need to memorise these. Just know: comfortably under the limits is what honest, fresh oil looks like; numbers hugging the ceiling are worth a raised eyebrow.

Polyphenols: how much of the good stuff made it in?

Total polyphenols — the natural antioxidants behind a fresh oil's bitterness and peppery finish — are reported in mg/kg. Around 250 mg/kg is the European benchmark most of the industry treats as the line for "high"; genuinely high-polyphenol oils start there, and early-harvest single-variety oils can run 600–1,000 mg/kg or more.

This is the line most supermarket labels never mention, because most supermarket oil wouldn't enjoy the comparison. We've written a full guide to reading a polyphenol number — the short version is: the figure only counts with a harvest date and a batch next to it.

The sensory panel: does it taste like extra virgin?

Chemistry can't do everything. The final test is a trained tasting panel scoring the oil for defects (rancid, musty, fusty, winey) and positive attributes (fruitiness, bitterness, pungency).

To pass as extra virgin: median defect of zero, fruitiness above zero. A good report will show more than a pass — real fruitiness, real bitterness, real pungency. On the plate, those scores are the grassy flavour and the peppery catch you can check with your own throat.

What good looks like, at a glance

Line	Legal EVOO limit	What good looks like
Free acidity	≤ 0.8%	≤ 0.3%
Peroxide value	≤ 20 meq O₂/kg	≤ 10, ideally single digits
K232 / K270 / ΔK	≤ 2.50 / ≤ 0.22 / ≤ 0.01	comfortably under all three
Polyphenols	no legal minimum	250+ mg/kg; 600+ is seriously high
Sensory	0 defects, fruitiness > 0	clear fruitiness, bitterness, pungency

The report only means much if it's from an independent laboratory — not the producer's own bench — and if it's tied to a batch, not a brand. Oil changes batch to batch; a two-year-old report tells you about a different oil.

That's why every KALTA tin carries a QR that opens the independent laboratory report for the exact batch inside — acidity, polyphenols, harvest week, the lot. You don't have to take the label's word for anything; the paperwork is the point.

Common questions

What acidity should good olive oil have?

Legally, extra virgin must be at or below 0.8% free acidity. Well-made oil usually sits below 0.5%, and excellent oils below 0.3%. It reflects fruit handling and pressing speed — you can't taste it directly.

What is the peroxide value in olive oil?

It measures early oxidation — how much the oil has reacted with oxygen — in meq O₂/kg. The extra virgin limit is 20; fresh, well-stored oils typically sit in single digits.

Do olive oil brands publish lab reports?

Very few do. All extra virgin is tested to be sold as such, but the results rarely reach the customer. When a brand does publish per-batch independent laboratory reports, you can check the acidity, freshness, and polyphenol numbers yourself.