How olives become oil…

The most suitable time for pick-up of the olives is when the veraison (change of the color of the fruit from green to purple and finally back) is at its 50/60%. In fact, at this time there is the highest quantitative concentration of oil and phenolic substances responsible for the organoleptic and nutritional oil qualities.

The period of olive harvesting, in Italy, goes from mid-October to the end of December and it is influenced by many factors such as: day and night temperature, rainfall, altitude, morphology of the land, exposure to the sun, age of the olive trees.

The olives are collected through a mechanical process and that the harvester, with a collection yield of about 3 working days per hectare of olive trees. According to the strict procedures for the classification of the oil as D.O.P (see procedure for obtaining and maintaining the label D.O.P.), the milling of the olives in the oil mills must be started within 24 hours from the collection. An average of 30 quintals of olives per day are harvested and delivered to the mill at the end of the same day; from that moment the milling process starts. This process is divided into several stages:

1. DEFOLIATION: in this first stage, the leaves are removed by means of a sifter supported by a fan that separates the leaves from the fruit.
2. WEIGHING of the olives net of leaves and any other impurities.
3. GRINDING of the olives with prior passage of them in a washer-dryer for washing and subsequent drying with fans to then move on to the CRUSHING, phase in which the olives are actually ground. From this moment the pulp of the fruit will no longer come into contact with the air so as not to alter the characteristics of the product.
4. The paste obtained from the milling is STORED in tanks (heated to a temperature of about 28 degrees centigrade and spinning around them warm water), where it is ground for about an hour in order to obtain the dissolution of the molecules-particles of oil that are trapped in the paste and fluidize it.
5. Only after the STORAGE we finally pass to the real pressing of the fluid pastes, thus obtained, passing it in the cylindrical presses with a mechanical centrifugal system that separates the solid part from the liquid one. At this point we have the OIL. At this stage the oil it is still RAW, this means that it still contains some impurities to eliminate: for this reason the oil is put in other centrifuges in which the force of gravity that is unleashed by the mechanical centrifugal process allows the separation of impurities still present up to 80/90%. After this phase we obtain the PURE OIL.
6. At this stage of processing, the oil can already be market but a possible final phase is contemplated: this consists in sucking the oil through a pump with paper filters that retain the very low percentage of impurities left and allow to obtain a perfectly FILTERED OIL, that is now 100% free of impurities.