Extraction or pressing is the process that finally sees the appearance of a product close to the oil we know: in this case too, there are various techniques to bring this stage of olive oil production to completion
Olive oil extraction is a natural process of agro-food transformation, which aims to extract oil from olive drupes. This transformation, carried out in a facility called an oil mill (or press), takes place in two fundamental phases: the milling of the pulp (grinding or crushing) and the subsequent separation of the oily part from the other components. About thirty minutes after malaxation, the paste is transferred via a pump to the “decanter“, a machine that separates the solid part from the liquid part by weight difference. The one used in our mill is a latest-generation decanter and works without adding water, producing an oil rich in aromas and antioxidants.
Olive oil extraction can be performed through three different types of processing:
Let us now analyze each of them in detail:
Cold pressing is the mechanical process consisting of the compression of the olive paste without the addition of hot water or the heating of the paste itself (remember that the paste is heated during the malaxation phase).
Cold pressing (to be declared on the label) as an oil extraction method is undoubtedly the most natural and is the one that provides a superior quality product that preserves the characteristics of the product from which it derives. Generally, the oil does not oxidize and has excellent organoleptic characteristics.
Labels always state “obtained by mechanical processes”, to which, depending on the extraction method used, the following may be added: “cold pressed (or first cold pressing)” or “cold extracted (produced, obtained)”.
Generally, the cold mill operates at temperatures not exceeding 27°C and this guarantees the best quality of the extracted oil, even at the cost of the yield, which will not be very high. The one used in our mill works without adding water, producing an oil rich in aromas and antioxidants, focusing everything on the quality of the final product and not on the yield. All processes for the production of extra virgin olive oil take place so that thermal conditions do not cause alterations of any kind in this precious food ingredient. Extra virgin olive oil is obtained through extraction and only by mechanical processes. The characteristics of each oil, starting from the color, flavor, and composition, can vary depending on the place of cultivation and the type of olives used.
From studies carried out, it seems that cold pressing:
Cold extraction is the mechanical process during which the paste is sent to the “Decanter” which extracts the different phases based on the physical principle of centrifugation and based on the difference in density. Here too, we remind you that the paste is heated during the malaxation phase.
Hot pressing, on the other hand, is obtained by heating the steel walls of the malaxer with hot water, so as to raise the temperature of the olive paste up to 29 – 30°C and maintaining it at a correct level of humidity. At these temperatures, some enzymes naturally present in the olives are activated, which are able to break the oil-water emulsion. These enzymes allow for higher oxidation and more elaborate processing of the paste, so the process must be kept much more under control by the operator in order not to alter the product. In this case, the oil extraction is aided by a chemical-physical process and allows for higher yields.
Hot pressing, with temperatures close to the boiling point of the oil, leads to oxidation and the loss of fundamental substances and the destruction of so-called unsaturated fats; therefore, the oil obtained is not edible and to make it so, it undergoes at least three treatments: deacidification, bleaching, and deodorization.
Hot-pressed oil (in which the seeds are preheated), as well as that obtained from second pressing (i.e., obtained from seeds already previously pressed), must therefore undergo a refining process.
Solvent oil extraction is carried out on the residues of hot extraction to recover that part of the oil that remained trapped.
The seeds are crushed and immersed in an organic solvent, generally a low molecular weight hydrocarbon such as hexane or heptane, through slow movements; the temperature is raised to 150°C and the solvent is evaporated; the oil is filtered under pressure and sent for refining while the seed residue is recovered and transformed into meal.
After discussing the various oil extraction methods, it is right to conclude with a piece of advice. One of the recurring questions in these cases is “which oil to choose?”.
The oil that provides the greatest benefits for human health is extra virgin olive oil, globally recognized as the best fat in the world. It is always to be preferred for our diet, especially if used raw. For frying, different oils can be used, which have a higher smoke point and run less risk of undergoing degradation. In any case, whatever our choice, for raw consumption let us remember to choose only cold-pressed oils. More expensive than others, but decidedly healthier for consumers.
A cold-pressed oil is recommended as it preserves the essence of the fruit and allows for the production of a quality food through production phases that aim to enhance the virtues of extra virgin olive oil, keeping alive and intact the tradition that makes our country a recognized excellence throughout the world.
The first cold pressing allows for the extraction of the content present in the fruits while preserving the quantity of minerals, vitamins, and substances rich in antioxidant properties for the body. This method is used to obtain the highest quality extra virgin olive oil according to the directives.
The best quality of oil possible, both for food and for use in cosmetics, is therefore obtained through cold pressing.
Extra virgin olive oil, especially if it is new oil, and even more so if it is organic and cold-pressed, is the best type of olive oil. Its acidity level is lower compared to other olive oils.
Organic certified oils can only be obtained by mechanical pressure (hot or cold) of the seeds: an oil obtained through solvent extraction can therefore never be considered organic.
Technician and expert in extra virgin olive oils, registered in the National Register, Campania section. Master oil miller with diploma, obtained from International Extravirgin Agency.
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