Two big families: virgin and refined oils
Olive oils fall into two large groups:
- Virgin oils: obtained only by pressing olives, through purely mechanical processes. No chemicals, no solvents, no high heat.
- Refined oils: treated with sodium hydroxide (to remove acidity), steam in autoclave (to remove off-flavours), and decolourisation. They are industrial oils, neutral in taste, without aroma.
Only virgin oils preserve the natural aromas, flavours and antioxidant compounds of the olives.
Extra virgin olive oil — the top tier
Legal parameters (EU Reg. 2568/91):
- Free acidity ≤ 0.8% (as oleic acid)
- Median of defects (Md) = 0: no sensory defects detected by a certified tasting panel
- Median of fruitiness (Mf) > 0: detectable fruity character
These are strict. To be extra virgin, an oil has to be flawless. Even a single defect (rancid, fusty, mouldy, fermented) disqualifies it.
Virgin olive oil, lampante, refined and "olive oil"
- Virgin olive oil: 0.8-2% acidity, Md ≤ 3.5, Mf > 0. Rarely sold at retail.
- Lampante: > 2% acidity, marked defects, no fruitiness. Not edible as-is. Sent for refining.
- Refined olive oil: lampante that has been chemically refined. Edible but anonymous: no aroma, taste or character.
- "Olive oil": blend of refined + virgin oil. The percentage isn't specified by law, so it can be 99% refined + 1% virgin. This is what supermarkets sell cheaply labelled simply "olive oil".
Olive pomace oil
Pomace is the solid residue (skin, pulp, pit fragments) left after pressing. Oil is extracted from it using chemical solvents (hexane). It is the lowest grade in the olive oil family: cheap, tasteless, and devoid of nutritional benefits.
How to read a label well
- Look for the exact phrase: "Extra virgin olive oil"
- Check origin: "100% Italian" or a specific region (Sannio, Chianti, Garda)
- Cultivar declared and harvest year
- "Cold-extracted" or "cold-pressed"
- Be wary of prices below 8-10 €/litre for Italian extra virgin: at that price it's mathematically hard to be a real EVOO.