The oil mill
Upon arrival at the mill, the olives are first weighed and, before proceeding to the oil extraction phase, they are subjected to defoliation and washing.
The branch remover, using fans and rotating shafts, removes branches and most of the leaves, which are then transformed into fertilizer or fuel. The washer, on the other hand, eliminates soil residues or other impurities using drinking water.
At this point the olives are ready for the next processing phases: pressing, malaxing, extraction, preservation, and filtration, which have followed a virtually unchanged operational logic for millennia.
the crushing
This is the stage during which the olives are crushed until a coarse paste is obtained that contains the peel (epicarp), pulp (mesocarp) and stones (endocarp) which perform a draining function and facilitate the subsequent separation of the oil from the paste.
The two most commonly used crushing methods are currently:
the traditional one, which determines a discontinuous production cycle and the modern one,
(OUR) characteristic of CONTINUOUS CYCLE mills.
The traditional method, which is gradually disappearing, is based on the use of granite millstones that crush the olives with their weight; the modern method instead uses hammer crushers or rotating discs, with the advantage of quickly crushing a large quantity of olives, obtaining a more uniform paste and minimizing the harmful contact of the olive paste with oxygen.
the kneading
It consists of a slow and continuous mixing of the olive paste inside a machine called a gramola.
This is a fundamental and delicate step as it allows us to break the water-oil emulsions that have formed during the pressing and reunite the droplets of must oil into increasingly larger drops that will be easier to extract in the subsequent extraction.
Today, malaxation is carried out in airtight stainless steel tanks to control the amount of oxygen that comes into contact with the paste, possibly also saturating them with inert gases such as nitrogen.
During the kneading phase, which lasts about 30 minutes, the temperature of the paste must never exceed 29 degrees Celsius in order to preserve the organoleptic characteristics and properties of the oil.
the extraction
It is the heart of the production process: from the paste obtained from the previous phases, the separation of the three components is carried out: pomace, vegetation water and oily must and can be discontinuous or continuous.
Extraction by pressure is a discontinuous system: the paste coming out of the mill is placed on circular filter panels, perforated in the centre (fiscoli).
These are stacked, interspersed with steel disks to even out the pressure, and stacked on trolleys placed under the press. Increasing pressure for about an hour allows the oily must (oil and vegetable water) to separate from the solids (pomace) that remain on the mats.
The continuous methods, most commonly used today, separate the oil from the solids not through pressure, but by using other physical principles.
The most common extraction method, centrifugation, exploits the different specific weights of the individual components. The paste from the malaxer is fed into a large centrifuge or decanter, which at high speed separates the pomace from the oily must, which is then separated into oil and vegetable water by a special centrifugal separator.
conservation and filtering
At the end of these operations, the oil obtained is always perfectly edible, but cloudy because it contains suspended mucilage, air bubbles, fragments of pulp, and water residues.
A period of decantation in special stainless steel containers is therefore necessary so that all foreign substances settle to the bottom (sludge).
After which it will be filtered before being bottled and released for sale.