👷 Olive mill operator

An olive mill operator is the specialist who turns olives into oil, running the crushing, malaxation and oil separation without letting the process spoil its quality. It is up to them whether the fruit is processed in time, whether the paste is mixed at a moderate 18–27 °C, and whether the result is extra virgin olive oil.

The work begins with receiving the harvest. The olives need processing as quickly as possible: according to the PROTA reference, within 1–3 days, otherwise the flavour changes and acidity rises; the specifications of Italy's protected oils allow the fruit to be held for 24 to 120 hours, most often 48. Then come leaf removal, washing, crushing into a paste, malaxation, separation of the oil in a horizontal centrifuge and final clarification in a vertical separator.

The most delicate stage is malaxation, the slow mixing of the paste during which tiny oil droplets merge. Researchers recommend 18–27 °C and 30–40 minutes: higher temperatures destroy phenolic compounds, and from 35 °C unwanted odours appear. The operator also chooses the system: a two-phase centrifuge works without added water, while a three-phase one needs 40–60 litres of warm water per 100 kg of olives, which leaves the oil poorer in phenols.

Today there are about 12,000 olive mills worldwide, and over 80% of them use centrifuges. Settings matter: in a study of 38 horizontal centrifuges in Catalonia, they extracted between 78 and 91% of the oil and worked best at 60–80% of capacity with about 8% water. Whether the oil is extra virgin is finally decided by the laboratory and a tasting panel of 8–12 trained tasters.

What the label allows. In the EU the words “cold extraction” are permitted only for extra virgin or virgin olive oil obtained below 27 °C, and “first cold pressing” only for oil from a hydraulic press. At a modern centrifuge mill, then, “cold extraction” is the only honest wording.