On the label of the oil we bring to the table we sometimes read the words cold pressing, but what does it mean? Let’s discover all the details of this process together.
In the production of oil the main phases are: washing, milling, malaxing, pressing, centrifugation and filtration. Cold pressing comes into play during malaxing, a phase in which the oil paste is stirred slowly and continuously to agglomerate the drops of oil.
We still often talk about first cold pressing, leaving us to imagine that there is a second pressing phase. However, this expression refers to ancient production techniques that have now fallen into disuse. In the past, olives were crushed twice with hydraulic presses to maximize the results of the pressing.
Cold pressing
Today, after milling, we immediately move on to the delicate continuous mixing of the olive paste, i.e. malaxing. With this step, the oil, still in the form of extremely small droplets (5-6 microns in diameter), collects into increasingly larger droplets, and therefore easier to drain.
We thus move towards the phase of pressing the must. This operation is carried out with hydraulic presses that generate pressures of 400 atmospheres with which the oily must is squeezed from the olive paste.
The extract obtained is placed on the so-called fiscoli, i.e. a series of disks stacked to form a column on which a press acts. This creates separation between the solid part, discarded and processed to obtain other oil residues, and the liquid part. The latter is centrifuged to definitively remove the water from the oil, which will be suitable for being classified as extra virgin.
In this mechanical process, it is possible to extract the contents of the drupes, maintaining the nutritional and physical characteristics of the extra virgin olive oil unchanged. This helps to keep its properties intact and enhance the benefits it can bring if included in your diet.
The definition of cold pressing derives from the fact that the temperature of the pressed olive paste must not exceed 27 degrees during malaxation. This applies only to extra virgin olive oil, while for other vegetable oils the temperature is significantly higher.
Difference between cold pressed and cold extracted
There is only one substantial difference between cold pressing and cold extraction: in the first case the separation between the various components of the paste is exploited based on the different molecular weight, in the second to separate the oil from the water use metal slats.
The real difference between cold pressing and cold extraction therefore lies in the separation of the three oil-water-pomace parts. Cold extraction is a less complex and more economical method. It requires less manpower and fewer controls during the entire production phase: this does not mean that the quality of the final product is not optimal.
Differences with hot pressing
There is also hot pressing, which involves the use of heat points during the malaxing, extraction with the decanter and washing of the presses after pressing.
With heat, oil extraction improves in terms of quantity, because it favors the union and therefore the accumulation of oil particles, but at the expense of quality. The oil is more fluid, but its durability is affected. Deterioration and oxidation will set in more quickly. The organoleptic properties also pay the price: hot-pressed oil loses the bitterness and tingle that distinguish it and is sweeter on the palate.
Cold pressing allows smaller quantities of oil to be obtained, but the excellent characteristics of the final product make the most attentive entrepreneurs choose this production method.
Olio Evo Toscano Del Chianti La Collina Del Sole 1 Litro Raccolta 2023/2024
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