Extra Virgin Olive Oil (EVOO): What It Means & How to Buy

Olive oil is graded, and the grades are law. “Extra virgin” — EVOO on menus and shelf tags — is not a marketing register but the top rung of a legal ladder that runs down through virgin, refined and pomace oil, each rung defined by how the oil was made and by what a laboratory and a tasting panel found in it. That makes this the most checkable premium shelf in the food aisle — and the checking is the point of every guide below.

Is “extra virgin” a legal grade in the UK?

Yes — unusually for a premium food word, it is defined to the decimal. The GB rules assimilated from Regulation (EEC) No 2568/91 grade every olive oil against chemical limits and a sensory test, enforced domestically through the Olive Oil (Marketing Standards) Regulations 2014, with inspection and sampling by the Animal and Plant Health Agency. To be extra virgin, an oil must be obtained from the olive solely by mechanical means — crushing, mixing, separating; no solvents, no refining — and then clear two bars at once. The chemical bar: free acidity of at most 0.80 per cent, a peroxide value of at most 20 mEq O2/kg, and three ultraviolet absorbency caps (K232 at most 2.50, K268 at most 0.22, Delta-K at most 0.01) that betray oxidation and refining. The sensory bar: a trained panel must record a median of defects of exactly zero and a fruitiness median above zero. Free acidity, note, is not sourness — it cannot be tasted at these levels; it measures the free fatty acids released when fruit is damaged, diseased or left waiting too long before the mill. An oil that aces the chemistry but tastes fusty is not extra virgin; nor is a delicious oil that fails the numbers.

Fig. I · Two bars, cleared at onceDiagram

The grade is defined by how the oil was made and by what a laboratory and a tasting panel found in it — a method, then two bars.

The method — before either bar

Obtained from the olive solely by mechanical means

Crushing, mixing, separating — no solvents, no refining.

The chemical bar — the laboratory

• Free acidityat most 0.80 %Not sourness — it cannot be tasted at these levels; it measures the free fatty acids released when fruit is damaged, diseased or left waiting too long before the mill.
• Peroxide valueat most 20 mEq O2/kg
• K232at most 2.50
• K268at most 0.22
• Delta-Kat most 0.01Three ultraviolet absorbency caps that betray oxidation and refining.

and · at once

The sensory bar — the tasting panel

• Median of defectsexactly zero
• Fruitiness medianabove zero

A trained panel’s finding: some fruitiness, zero defects.

An oil that aces the chemistry but tastes fusty is not extra virgin.

Nor is a delicious oil that fails the numbers.

Fail any one, and the oil grades lower — whatever the label hoped.

The retail bottle carries obligations of its own: a fixed category sentence — “superior category olive oil obtained directly from olives and solely by mechanical means” — a designation of origin, advice to store away from heat and light, and a sealed container of at most five litres.

What are the other grades of olive oil?

Below extra virgin the ladder runs: virgin (mechanically made, minor blemishes allowed), lampante (failed oil, historically lamp fuel, lawful only as refinery feedstock), refined (lampante scrubbed clean and stripped of character in the process), plain “olive oil” (refined oil brought back to life with a measure of virgin), and olive-pomace oil (solvent-extracted from the spent paste, then refined). The designations are international — the International Olive Council’s trade standard defines the same ladder for the world trade — and in Great Britain only four rungs may be sold at retail: extra virgin, virgin, plain “olive oil”, and olive-pomace oil.

One row repays a second look. Refined olive oil posts a lower acidity figure than extra virgin is allowed — because refining removes acidity along with everything else — so a low number alone never proves a fine oil. Acidity means something only inside the virgin grades, where nothing has been done to engineer it. A bottle labelled simply “olive oil” must say what it is in the regulation’s own words: “oil comprising exclusively oils that have undergone refining and oils obtained directly from olives”.

What actually decides quality inside the grade?

The grade is a floor, not a score: two oils can both be lawfully extra virgin and be worlds apart. Four levers separate them. Fruit condition — sound, undamaged olives; bruised or fermenting fruit is where the panel’s defect vocabulary of fusty, musty, winey-vinegary and rancid comes from. Speed — hours rather than days between tree and mill, because free acidity climbs while picked fruit waits. The mill itself — after crushing, the paste is slowly mixed before the oil is separated, and this malaxation is where the fruit’s phenolic compounds are actually formed; in Greek trials the phenolic maximum came at about fifteen minutes of mixing, and stretching the same batch to ninety minutes cut one oil’s total from 1,160 to 364 mg/kg. Temperature, meanwhile, is regulated on the label rather than in the vat — “cold extraction” is a fixed below-27°C statement, examined with its hydraulic-press sibling in cold pressed olive oil. And harvest date — in the largest study of Greek oils, 5,764 samples measured by NMR across more than a decade, phenolic content falls steadily as picking runs from September into January, which is why early harvest olive oil commands its premium and why oils above 500 mg/kg of total phenols have come to be called high-phenolic. What those milligram figures mean, and how a laboratory arrives at them, is in high polyphenol olive oil.

Variety, by contrast, guarantees less than labels imply. Koroneiki, the small olive behind most Greek oil, spans an enormous phenolic range across that same dataset — from nothing to 2,637 mg/kg, more than twice the line the study drew for its exceptionally-high top five per cent — so the harvest date and the mill decide, not the name of the tree. And where the name on a bottle is a place rather than a variety, it earns separate scrutiny: Kalamata olive oil takes apart the best-known Greek example, and Greek olive oil maps the whole country — varieties, regions and every protected name on the GB register.

Fig. II · Four levers inside the gradeDiagram

The grade is a floor, not a score: two oils can both be lawfully extra virgin and be worlds apart. Four levers separate them.

Fruit condition

Sound, undamaged olives

Bruised or fermenting fruit is where the panel’s defect vocabulary comes from — fusty, musty, winey-vinegary, rancid.

Speed

Hours rather than days, tree to mill

Free acidity climbs while picked fruit waits — the first ceiling on Fig. I’s chemical bar.

The mill — malaxation

After crushing, the paste is slowly mixed before the oil is separated — where the fruit’s phenolic compounds are actually formed

About 15 minthe phenolic maximum1,160 mg/kg

90 minthe same batch, stretched364 mg/kg

Greek trials — one oil, one batch; both bars to one scale.

Harvest date

Phenolic content falls steadily as picking runs from September into January

SeptemberJanuary

The largest study of Greek oils — 5,764 samples measured by NMR across more than a decade. Oils above 500 mg/kg of total phenols have come to be called high-phenolic.

Not a lever

The name of the tree

Koroneiki, the small olive behind most Greek oil, spans nothing to2,637 mg/kg across the same dataset — the harvest date and the mill decide, not the name of the tree.

Can you cook with extra virgin olive oil?

Yes. Across the olive-growing Mediterranean it is the everyday cooking fat, and ordinary home cooking is exactly what most of it is bought for. What heat spends is character: the green, grassy aromas of a fresh oil fade in the pan, and the phenolic numbers drift down with time and temperature — the honest argument for cooking with a modest extra virgin and finishing plates with a remarkable one, not for keeping the grade out of the kitchen. Temperatures, trade-offs and the smoke-point folklore are in cooking with extra virgin olive oil; for where the oil goes raw, start with our Greek salad dressing.

Does olive oil go off?

Yes — and this is where oil and honey part company on our own shelves. A sealed jar of honey keeps almost indefinitely; olive oil is a fresh product that begins oxidising the day it is pressed, and its enemies are light, heat, air and time. The decline is measurable: the Greek qNMR dataset drew its high-phenolic line at 500 mg/kg precisely so that a bottle crossing it would still hold half that figure a year after bottling. Dark glass and tins are the trade’s answer; the mandatory storage advice — away from heat and light — is the law’s. So buy oil young, keep it sealed and dark, and finish an opened bottle rather than curating it. Shelf life, the signs of a tired or rancid oil, and what a best-before date does and does not promise are in does olive oil go off; the honey shelf’s very different answer is in does honey go off.

What may a premium label say — and what must stand behind it?

The optional indications are a study in evidence discipline. “Cold extraction” may appear only on virgin or extra virgin oil obtained below 27 °C by percolation or centrifugation — the modern method; “first cold pressing” is reserved for oil from a first pressing in a traditional hydraulic press, which almost no quality mill still runs. Print an acidity figure and the peroxide value, wax content and ultraviolet absorbency must appear beside it, in the same field of vision and the same size lettering — all four numbers or none. Taste words such as fruity, bitter and pungent are controlled vocabulary, permitted only with a panel assessment behind them. A harvesting year may be shown only where the entire contents of the container come from it. Every rule points the same way: on this shelf, a claim is only as good as the analysis behind it. The whole label, mandatory and optional, reads in order in how to read an olive oil label; what an organic logo certifies — and does not — is in organic olive oil; and how to weigh a shelf of candidates is in best olive oil UK.

Is olive oil a seed oil?

No. Olive oil is a fruit oil — the olive is a stone fruit, and extra virgin is its flesh squeezed by mechanical means alone, closer to a fresh juice than to anything else in the oil aisle. Seed oils are generally extracted from seeds with heat and solvents and then refined towards neutrality; olive oil has refined grades of its own, as the table above shows, but the extra virgin bottle is the aisle’s conspicuous exception to the refining rule. The classification question, and why it has lately become an argument, is taken slowly in is olive oil a seed oil.

What does the research say?

More than for most foods we cover, and we read it the way we always read research: findings first, mechanisms explained, limitations stated where they matter. The trials on olive oil in the diet are read in full at is olive oil good for you; the phenolic story — oleocanthal, oleacein, hydroxytyrosol, and what has actually been measured in people — at olive oil polyphenols; and the question every dog owner eventually asks at olive oil and dogs. This page stays on its own side of that line: composition, process and law.

Where THYMELIA stands

THYMELIA is a UK house of Greek foods: Cretan bee products from Chania — that world begins at raw honey — and, the reason this section exists, an extra virgin olive oil line in preparation from the hills above Kalamata, in the southern Peloponnese, where the olive harvest runs from October into winter and the earliest picking makes the greenest, most phenolic oil. Nothing on this page describes a product of ours: there is no shop and no bottled oil. When there is oil, it will be held to the standard this page teaches — free acidity, peroxide value, ultraviolet absorbency and phenolic content published per batch against the batch number, exactly as the honey side will publish HMF and diastase. What we test is at testing, and how a harvest earns its place here is at sourcing.