It takes about 10 pounds of olives to create one liter of olive oil. The olives are processed using time-tested processes that have been passed down for generations to produce the olive oil that is a staple in many cultures around the world.
In the northern hemisphere, the harvesting of olives starts in October (for green olives) and can last until March (for black olives). Growers use a variety of methods to collect the fruit, including letting the olives fall naturally; climbing the trees to pick them by hand; or beating or shaking the fruit off the branch with sticks, poles, rakes or mechanical shakers. While harvesting can be exhausting and tedious work, many communities bond over the harvest, participating in a work that has been passed down through the generations.
Once the olives have been harvested, about 90% of the crop is turned into oil. Despite the wide variety of equipment that can be used while making olive oil, the basic steps are the same for individual growers and large commercial mills.
The first step is to clean the olives. Stems, leaves, twigs and other debris must be detached and the olives must be washed to remove any dirt or pesticides.
Once the olives are clean, they are crushed into a paste. Crushing the olives tears the flesh cells, helping the oil to release from the fruit.
When all the olives are crushed, they must be malaxed (mixed) for about 20-45 minutes. The malaxing is a crucial step in the process as it allowed the small oil droplets to combine with the bigger droplets, increasing the overall oil yield.
The next step in separating the actual oil from the rest of the olive. Originally the oil was extracted using an oil press, often called a first press or cold press. Modern oil extraction is usually done by the process of centrifugation. The olives are put into a rotating device called a decanter, which rotates at approximately 3,000 rpm. This creates a high centrifugal force that separates the olive according to the densities of its components (solid, water & oil). Usually the olive is processed more than once in order to ensure that all water and solids are completely separated from the oil.
At this point the oil is put in large tanks or barrels. Any final separation happens through simple gravity (called racking the oil). Finally the oil is ready to be filtered and packaged for use.