Olive oil

The olives are harvested by hand or by shaking the tree with a stick or by machinery. After harvesting, the fruit is transported to the olive oil mill as soon as possible to avoid fermentation and the development of mold that degrades the quality of the olive oil. In the olive oil mills, the processing begins with weighing, separating and washing of the olives. The olives, which have been placed in crates or bags, are transported by elevators to a large basin located on a hill in the olive oil mill. From there, they fall through funnel-shaped pipes into crushers or millstones. The olive pulp is then kneaded, by stirring for half an hour or an hour in devices called "malaxers". The olive mass may also be heated there to improve the oil yield. For good quality olive oil, kneading is done "cold", that means at room temperature.

After kneading, in traditional presses (which are now rare in Greece) with the help of powerful hydraulic presses, the olive liquids are extracted, which is a mixture of olive oil with watery components of the fruit. In modern olive oil mills, the separation of liquids from solids is done by centrifugation in devices called "decanters". The solid by-product that remains is called "core". The liquids taken from the decanter (basically a mixture of water and oil) are directed to one or more centrifugal separators where the oil is separated from the aqueous part due to the difference in density.

Olive oils that are commercially available are divided into edible and industrial. The first are basically divided into virgin olive oils and simple olive oils. The latter are mixtures of virgin olive oil with refined olive oil or pomace oil. Depending on the ripening stage of the olives, some virgins are called earlz harvest olive oils. The average yield from 100 kilos of olives, which varies depending on the quality, year and processing system, is about 10-25 kilos of oil, 35-50 kilos of olive core and 35-50 kilos of liquid residues. In some countries, the sale of a blend of olive oil with seed oils is allowed. This is not allowed in the European Union.