Virgin oil extraction uses only shock, pressure, centrifugation, decantation, filtration, surface tension and mechanical treatment of emulsions. The use of heating is allowed, at moderately high temperatures, to increase the oil yield.
Other techniques include the use of physical and chemical methods. However, regulations and quality standards impose the exclusive use of mechanical methods. The oil obtained through the use of chemical and physicochemical methods is therefore identified with different types of products and distinct from the virgin oil. In the case of olive oil, physical and chemical methods are secondary processes implemented in separate plants, to grind non-edible virgin oils or to extract the lipid fraction of seeds.
Before the actual extraction, the olives must be prepared, it is the object of the preliminary operations. These are operations taking place between the harvest and the grinding initially carried out by the oil mill