Olive harvesting season starts from early October, goes through late December. After olives are picked, transported to the factory, where they are immediately washed and crushed. Traditional crushing is by mill stones, but it is by steel blades today, that gives absolutely better results.
Crushed olives become a paste. Modern milling is very gentle in order to avoid overheating of the paste. It needs to be stirred to release the oil. Paste is mixed at slow speeds (15-20 rpm) for between 30 minutes and 60 minutes.
Later, the paste is pumped into an industrial decanter where the phases are separated using centrifugation. A centrifuge pull out the oil and water.
Water is removed and what we get is olive oil, ready to be stored.
Generally, 4 to 8 kilograms of olives make one liter of extra virgin olive oil. Olive paste and oils, must not exceed 27 ˚C at any step in the processing to be named as “cold-pressed” extra virgin olive oil.
The rest of the olive paste goes for another process of production. This is a chemical/physical process to get rest of the oil. Product of this process is pomace oil, which is far different from olive oil in qualities.