The basic steps in making olive oil are always the same and no matter what kind of equipment is used. Look at the steps of olive oil production process.
- Cleaning the olives: The first step in the oil extraction process is cleaning the olives and removing the stems, leaves, twigs, and other debris left with the olives. The olives should be washed with water to remove pesticides, dirt, etc.
- Grinding the olives into a paste: The second step is crushing the olives into a paste. The purpose of crushing is to tear the flesh cells to facilitate the release of the oil from the vacuoles.
- Malaxing the paste: Malaxing (mixing) the paste for 20 to 45 minutes allows small oil droplets to combine into bigger ones. It is an indispensable step. 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. The most common mixer is a horizontal trough with spiral mixing blades. Longer mixing times increase oil yield but allows a longer oxidation period that decreases shelf life.
- Separating the oil from the vegetable water and solids: The next step consists in separating the oil from the rest of the olive components. This 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 separately. 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 by a second centrifuge that rotates faster. The oil is then left in tanks or barrels where a final separation, if needed, happens through gravity. This is called racking the oil. Finally the oil can be filtered, if desired.