Methods of Extracting EVO Oil, the Differences

L’extraction or pressing is the process that finally sees the appearance of a product close to the oil we know: again, there are several techniques for bringing this stage of olive oil production to fruition

Methods of extracting EVO oil

Olive oil extraction is a natural process of agri-food processing, the purpose of which is to extract oil from the drupes of the olive tree. This transformation, carried out in a facility called an oil mill (or oil press), occurs in two basic stages: the milling of the pulp (milling or crushing) and the subsequent separation of the oily part from the other components. About thirty minutes after the milling, the pulp is transferred by 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 state-of-the-art decanter and works without the addition of water, producing an oil rich in aromas and antioxidants.

Olive oilextraction can be performed through three different types of processing:

• Cold pressing
• Hot extraction
• Solvent extraction

Let us now go on to analyze each of them in detail:

Cold Extraction

Cold pressing is the mechanical process of compressing the olive paste without the addition of hot water or heating the paste itself (remember that the paste is heated during kneading).

Cold pressing (to be declared on the label) as a method of oil extraction is undoubtedly the most natural and is the one that provides a superior product that retains the characteristics of the product from which it is derived. The oil generally does not oxidize and has excellent organoleptic characteristics.

Labels always say “obtained by mechanical processes,” to which may be added, depending on the extraction method used, the words: “cold-pressed (or first-pressed)” o “extracted (produced, obtained) by cold process.”

In general, the cold press operates at temperatures no higher than 27°C, which 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 the addition of 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 ofextra virgin olive oil take place in such a way that thermal conditions do not cause alterations of any kind in this precious food ingredient. Extra virgin olive oil is obtained by extraction and only by mechanical processes. The characteristics of each oil, starting with color, flavor and composition, can vary depending on where it is grown and the type of olives used.

From studies it appears that cold pressing:

• Improves the quality of the oil,
• It enhances the body and aroma of the fruitiness of the oil,
• improves oil preservation because polyphenols, which are excellent natural oxidants, are not lost to wastewater.

L’COLD EXTRACTION is the mechanical process during which the pulp is sent to the “Decanter” which extracts the different phases based on the physical principle of centrifugation and according to the density difference. Here again, we recall that the paste is heated during the kneading stage.

Hot Extraction

Hot pressing, on the other hand, is achieved by heating the steel walls of the press by means of hot water, so as to raise the temperature of the olive paste to 29 to 30°C and keeping it at the right moisture level. At these temperatures certain enzymes naturally present in olives are activated that are able to break down 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 so as not to alter the product. In this case, oil extraction is aided through a chemical-physical process and allows higher yields.

Hot pressing, with temperatures close to the boiling temperature of the oil, results in oxidation and loss of key substances and destruction of so-called unsaturated fats, so the resulting oil is inedible and to make it edible it undergoes at least three treatments: deacidification, decolorization, and deodorization.

Hot-pressed oil (in which the seeds are preheated), as well as oil obtained by second pressing (i.e., obtained from previously pressed seeds), must therefore undergo a refining process.

Extraction with Solvents

Oil extraction with solvents, is performed on the residue of hot extraction to recover that part of the oil that is trapped.

The seeds are crushed and immersed in an organic solvent, usually a low-molecular-weight hydrocarbon such as hexane or heptane, through slow motions; 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 processed into flour.

Which method to prefer?

Having discussed what the various methods of oil extraction are, it is only fair to conclude with some advice. One of the recurring questions in these cases is “which oil to choose?”

The oil that provides the greatest health benefits for humans is extra virgin olive oil, globally recognized as the best fat in the world. It is always preferred for our diet, especially when 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 definitely healthier for consumers.

A cold-pressed oil is recommended as it preserves the essence of the fruit and makes it possible to produce a quality food through production stages that aim to enhance the virtues ofextra virgin olive oil, keeping alive and intact the tradition that makes our country an excellence recognized worldwide.

The Benefits of Cold Pressed Oil.

The first cold pressing allows extracting the content present in the fruits while preserving the amount 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 guidelines.

The best possible quality of oil, whether food grade or used in cosmetics, is therefore obtained by cold pressing.

Extra virgin oil, especially if it is new oil, even more so if organic and cold-pressed, is the best type of olive oil. Its degree of acidity is lower than other olive oils.

Oils with organic certification can only be obtained by mechanical pressure (hot or cold) of the seeds: an oil obtained by solvent extraction can therefore never be considered organic.

Posted by:

Alfio Lo Conte

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Tecnico ed esperto degli oli extravergini di oliva, iscritto nell’Elenco Nazionale sezione Campania. Maestro di frantoio con diploma, conseguito presso International Extravirgin Agency.

Read more articles by: Alfio Lo Conte