Tasting olive oil: defects and positive attributes

Olive oil is one of the few foods in the world whose legal classification includes a sensory test. To be sold as extra virgin, an oil must not only pass laboratory measurements — it must also pass a tasting by a trained panel. This article explains what that panel looks for, and how to apply the same logic at home.

The two conditions for extra virgin

Under the International Olive Council's sensory standard, an oil qualifies as extra virgin only if both conditions hold:

1. The median of defects must be zero. The panel must detect no defect at all.

2. The median of fruitiness must be above zero. The oil must smell of fruit.

If the defect median is above zero but no higher than 2.5, and fruitiness is present, the oil is classified as virgin. Once the defect median rises above 2.5 — or if there is no defect but fruitiness is zero — the oil becomes lampante, and cannot be sold for consumption without refining.

This has an important consequence: an oil can have low acidity and still fail to be extra virgin. Chemical measurement and sensory assessment are separate gates and both must be passed. On what acidity actually measures, see what acidity means in olive oil; on the differences between grades, see extra virgin, virgin and riviera explained.

The three positive attributes

The panel scores only three positive attributes:

Fruity. The smell of sound, fresh olives. It may be "green" (grass, leaf, green apple, artichoke) or "ripe" (ripe fruit, almond). Both are positive; which dominates depends on harvest timing and variety.

Bitter. A bitter taste felt at the back of the tongue, pronounced in early-harvest oils.

Pungent. A burning felt in the throat on swallowing, often causing a cough. It is the direct signature of the phenolic compound oleocanthal — see oleocanthal and polyphenols.

The most common consumer error is to mistake bitterness and pungency for defects. Both are defined in the standard as positive attributes and both indicate phenolic content. A "smooth, never harsh" oil is usually either low in phenols or old.

The six basic defects

The standard names each defect and defines its origin. Recognising a defect is valuable because it tells you where in production something went wrong.

Read practically: five of the six are harvest and processing faults, and one — rancidity — is a storage fault. The story of a bad oil is usually written not at the mill but in the time the fruit spent getting there. This is why fruit should be milled on the day it is picked.

Tasting at home

The panel method cannot be reproduced exactly at home, but its logic can.

The glass. Use a dark, narrow-mouthed glass. Panels use blue glasses so the taster cannot see the colour. Colour says nothing about quality — it varies with variety and harvest date. The belief that greener oil is better is common and wrong.

Warming. Cover the glass with one palm and cradle it with the other. The target is close to body temperature; warmth releases the volatile compounds.

Smelling. Lift your hand and inhale deeply. Is there fruit? Something recognisable — grass, leaf, green almond, ripe fruit? Or sack, damp, vinegar, stale walnut?

Tasting. Take a small sip and spread it across your tongue. Draw air through your teeth — this carries the aroma to the nasal cavity. Look for bitterness at the back of the tongue and pungency in the throat as you swallow.

Resetting. Clear your palate with a slice of apple or water between oils.

The three most common defects

Rancid. The defect most often found in supermarket oil. It smells of stale walnut or paint, and is caused by light, heat and time. Oil sitting in a clear bottle under shop lighting develops it. This is why olive oil is sold in dark glass or tin, and why it should be kept cool and dark at home rather than beside the stove.

Fusty. Common in home production and small operations, and produced by leaving fruit in sacks or piles for a few days. Once formed it cannot be undone.

Winey. Comes from crushed fruit left waiting, usually fly-damaged or ground-collected.

Frequently asked

Does colour indicate quality? No. It depends on variety, harvest date and chlorophyll content. Panel glasses are blue precisely so the taster cannot see it.

Is bitter oil spoiled? No — the opposite. Bitterness and pungency are positive attributes in the standard and signal phenolic content.

It burns my throat, is that normal? It is normal and a good sign — the effect of oleocanthal.

There is sediment at the bottom. Is it bad? Unfiltered oils naturally carry sediment. But sediment can ferment over time, so unfiltered oil should be used sooner.

Does solidifying in the fridge prove purity? No. The point at which an oil clouds depends on its fatty acid composition and is not a purity test. This is a persistent myth.

Sources

• International Olive Council, COI/T.20/Doc. No 15/Rev. 11 (2024) — Method for the sensory assessment of virgin olive oil: positive attributes, defect definitions and origins, profile sheet.
• International Olive Council, Trade Standard REV-20 (2024): defect and fruitiness median thresholds for each grade.