The trasformation of the olives into oil

After arrival at the olive mill, the olives are weighed and stored in a fresh and ventilated area, waiting for the beginning of the oil extraction process.
This process begins with the cleaning of the olives, consisting of two stages: the elimination of the leaves, little branches and residue of dirt that are found among the olives and the washing of the olives using potable water.

The next stages - crushing, malaxing, separation - are of the utmost importance for the production of the extra virgin olive oil and may be described as follow:
- Crushing: the purpose of crushing the olives into a paste is to tear the cells to facilitate the release of the oil from the vacuoles. This step can be done with stone mills (traditional discontinuous extraction method), metal tooth grinders, or various kinds of hammermills (modern continuous extraction method).

- Malaxing: the malaxing (mixing) of the paste for 20 to 45 minutes is an indispensable step because allows small oil droplets to combine with each other to form bigger ones. The paste can be heated or water added during this process to increase the yield, although this generally results in lowering the quality of the oil. Longer mixing times increase oil yield but allow a longer oxidation period that decreases the shelf life.

- Separation: this step consists of separating the oil from the rest of the olive components. This operation used to be done with presses, but is now done by centrifugation, except in old facilities. Some centrifuges are called three-phase because they separate the oil, the water, and the solids distinctly. The two-phase centrifuges separate the oil from a wet paste. In most cases, the oil coming out of the first centrifuge is further processed to eliminate any remaining water and solids in a second centrifuge that rotates faster. The oil is then left in tanks where a final separation, if needed, occurs through gravity. Finally the oil can be filtered, if desired.