Acidity: what we're actually talking about
Free acidity is measured in a laboratory. It indicates the percentage of free fatty acids (as oleic acid) present in the oil.
Free fatty acids indicate that triglycerides (how fats are "packaged" in the olive) have broken down. This happens when:
- Olives have been damaged on the tree or during harvest
- They were poorly stored before milling (piled up, fermented)
- Too much time passed between harvest and pressing
- Olives suffered olive fly attacks or other pests
Acidity measures the quality of olives and process, not the flavour of the oil.
Why acidity isn't tasted
A surprising truth: the human body cannot sense an oil's acidity through its senses, whatever the value.
When you feel an oil "pinch" your throat or have a strong bitter aftertaste, you're sensing polyphenols, not acidity. These are different things:
- Acidity = chemical parameter. Tells about preservation. No perceptible taste.
- Pungency and bitterness = sensations from polyphenols (oleocanthal, oleuropein). Mean freshness and antioxidant richness.
Legal parameters
Per EU Reg. 2568/91, to be extra virgin an oil must have:
- Free acidity ≤ 0.8%
Premium artisan EVOOs typically have:
- Acidity between 0.15% and 0.30% — meaning healthy olives, harvested at the right time, processed quickly
- Our monovarietals oscillate between 0.18% and 0.28% depending on the year
Polyphenols: the real "quality flavour"
Polyphenols give EVOO its intense flavour and health properties:
- Oleocanthal: throat pungency. Anti-inflammatory effects similar to small doses of ibuprofen.
- Oleuropein: characteristic bitterness. Powerful antioxidant.
- Tyrosol, hydroxytyrosol: cardiovascular protection.
To carry the claim on the label, an oil must contain at least 5 mg of hydroxytyrosol and its derivatives per 20 g of oil (= 250 mg/kg), with a recommended daily intake of 20 g. A good Ortice monovarietal exceeds this threshold for HT and derivatives.