Today we will learn about the production stages of Extra Virgin Olive Oil, the techniques and the process for its production, having Italian Tradition given you a little introduction about its main characteristics and nutritional properties just last week.
What are the production stages of Extra Virgin Olive Oil?
Stage 1: olive harvest
The chemical and compositional features of the olive change sensibly during maturation. The maturation stage is influenced by the variety, soil, climate and cultivation practices. The best moment to harvest them, both in terms of quality and of organoleptic and nutritional characteristics of the oil, is when the fruit changes color (veraison).
To get a high quality oil, the olives have to be picked straight from the tree through manual detachment or through machinery such as facilitators that allow olives to fall in nets place just above the ground or with the help of comb-shaped shakers. All this to avoid any trauma to the drupes and to allow the production of excellent Extra Virgin Olive Oil.
Stage 2: transportation and storage of the olives
Olive transportation and storage stages are certainly among the most critical step of the entire production cycle. Olives have to be processed as soon as possible after harvest, preferably within 12 hours, especially if the olives are very ripe.
During transportation mechanical damages must be kept to the minimum in order to avoid fermentation and mold formation. The best way to carry olives around is through ventilated plastic boxes, avoiding bags that stop any air from going in.
Stage 3: defoliation and washing
The olives before going in the actual processing cycle must undergo defoliation and washing operations both for health- and quality-related reasons. This stage has the goal to remove leaves, branches and any potential foreign matter present in the olive batch undergoing processing in order to prevent the olives from having excessive chlorophyl and to avoid damaging the metal crusher for the making of olive paste, and the centrifuge decanter for the separation of the oil.
The defoliation usually happens through a fan that works through aspiration which is able to channel leaves and branches through a dedicated duct, towards the outside. Meanwhile, the washing of the fruits is carried out with potable water to change frequently in order to obtain a good olive hygiene and so as to prevent bad odors that could contaminate the oil.
Stage 4: olive pressing
In the process of pressing, the olives harvested, after being cleaned and washed, undergo mechanical operations in the mill with the aim to break the skin, pulp and stone thus causing the release of the oil. During this stage, emulsions of water contained in the olives and the oil come to be.
For this step the following tools can be used:
Traditional mullers (molazze), which are big granite wheels with a slow rotating movement. From this mechanism you obtain high quality oil because the molazze operate slowly but consistently with no significant increase in the paste’s temperature.
Mechanical crushers which go much faster having an elevated number of revolutions per minute, ultimately they are much faster than traditional molazze.
Stage 5: kneading
It is the process that follows olive pressing or crushing and has the goal to break the emulsion between the water and the oil. In takes place in steel tubs called malaxer where helicoidal blades rotate and keep mixing the oil paste.
Stage 6: Extra Virgin Olive Oil extraction
The extraction is a process that yields results which are very much similar to the product s we know it: in this case too there are many techniques to deal with this stage of production, let us briefly check them out:
- Pressure: kneaded paste is spread, about 3cm thick, on special mats or filtrating circular panels made of synthetic fiber. What we get is an oil which we find at the bottom of the press, while the mats contain the waste olive residues.
- Centrifugation: the decanter deals with the extraction of the oil out of the olive paste through centrifugal force and thanks to the different specific weight of the several stages to separate (oil, water and residue). With this system separation is efficient and there are no risks of fermentation.
- Percolation through selective filtration: the olive kneaded paste is place inside a special sinolea extractor featuring thousands of stainless steel gills placed like a comb. This system is based on the varying superficial tension of oil as opposed to water on metal objects. The Extra Virgin Olive Oil that results from it is of the highest quality because there are no temperature increases and because it maintains a great aromatic component as the olive paste is not stressed. The processing is completely cold and causes no oxidation of fat acids and polyphenols.
Stage 7: Extra Virgin Olive Oil packaging
The last part of the oil production chain happens in rooms very close to the processing area, which comply with HACCP rules. Before the packaging, the oil is filtered and then bottled and tightly sealed. In this phase it is extremely important to limit contact with air and processing times in order to avoid altering the taste of the oil.
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