Unfiltered oil is in fashion. Although it is a delicate, perishable and cloudy-looking product, many consumers choose it intuitively because it seems more natural, less manipulated and, consequently, better than a filtered oil. According to Enrique Fernández Marín, creator of the online store Dando la vara, which also carries out all kinds of informative activities on the culture of extra virgin olive oil, “it is curious that the consumer finds a cloudy oil more attractive than a bright, clear, limpid and without turbidity.” And even more so taking into account that “unfiltered oil is in no way better than filtered oil, and its turbidity, color and texture have nothing to do with better quality.”
Why, then, have unfiltered oils become fashionable? There are many explanations. Probably one of the most feasible is the so-called chemophobia, an irrational fear of chemical and processed products and a tendency to consider that natural is better by definition. It is explained by JM Mulet, a graduate in Chemistry and a doctor in Biochemistry and Molecular Biology from the University of Valencia, who points out that “we are human and it is precisely that humanity that makes us think that there is a kind of truth in nature that makes it natural is better than artificial. There are no figures or data to prove that this is the case. Precisely in the time of our grandmothers there were epidemics of goiter, typhus, botulism... A series of diseases that fortunately have been controlled and even eradicated in recent years."
Therefore, although in general terms we tend to irrationally choose what seems most natural to us at first glance, in the case of olive oil it is not only not justified, but it ends up being counterproductive. According to Fernández Marín, “an unfiltered olive oil contains, in addition to the EVOO itself, also water, pulp and stone. As before bottling it did not go through a filtering process nor was it decanted correctly, we see that this oil is cloudy. This is because it contains vegetation water (which the olive naturally has), and remains of bone and pulp that accompany the oil.”
When an oil is filtered, both water and organic remains are eliminated, which contributes to "extending its life and continuing to evolve within the container." In the case of unfiltered oil, this water is not eliminated, which causes, as Fernández Marín explains, that “the oil increases its acidity and therefore lowers its quality.” This is because “the structure is broken, leaving free the fatty acids that were previously all together, in the form of triglycerides. The greater the amount of free fatty acids, the greater the acidity, the greater the deterioration and, therefore, the lower the quality.”
Regarding the remains of bone and pulp that remain in the unfiltered oils, Fernández Marín explains that “they tend to ferment, so that the more time passes, the more the oil deteriorates.” The director of the La Patente cooking school in Barcelona, Àngels Puntas, explains, for her part, that unfiltered oils “can be interesting at a given moment to provide a different nuance to the dishes, but it is essential that they be consumed immediately. Otherwise, the sediment that forms will ferment and change the properties of the oil.” Furthermore, taking into account that unfiltered oils are more expensive than filtered ones, “we will have paid more money for nothing.” In this sense, Puntas assures that it is ultimately absurd to charge more for a less manipulated product, since "it requires less work to produce an unfiltered oil than a filtered one."
For his part, Fernández Marín remembers that those unwanted odors and flavors that appear when it takes time to consume an unfiltered oil "are harmless", so we should not worry if we consume it. Although he admits that it is true that virgin olive oil loses some antioxidants in the filtering process, the person in charge of Dando la Vara assures that it is a price worth paying if we take into account that "it is better to lose some antioxidants than to consume a extra virgin olive oil that, after about three months of being bottled, generates so many defects that it is no longer even an extra virgin.”
In this sense, before thinking about whether we prefer an unfiltered or a filtered oil, it is important to be clear about the differences between the types of olive oils that are marketed. Thus, extra virgin olive oil, the most appreciated, is nothing more than the juice of the best olives that has gone through a filtering process. The virgin olive oil is also of impeccable quality, although it does not come from the best olives but from others that may have some small defects. This influences its acidity and the fact that it contains a lower amount of antioxidants, although it is still a high quality oil, ideal for frying. Finally, the olive oil undergoes a refining process, which influences its organoleptic properties. Therefore, Puntas recommends “always choosing virgin and extra virgin olive oils.”
Regarding filtering the oils, Fernández Marín points out that there are two main ways to do it: using diatomaceous stones or with cellulose plates. Diatom stones “are fossilized remains of silica from the cell walls that surrounded these microscopic algae, which are responsible for retaining moisture and organic remains.” For their part, the compacted and consecutive cellulose plates help to filter and polish the oil using an organic agent such as cellulose.
In Fernandez Marín's opinion, for many oil producers it is beneficial to save the time and money involved in the filtering process, so "they are not interested in informing about the disadvantages that unfiltered oil may have." In fact, taking into account that the latter is more expensive and that producing it represents savings for producers, the business is served. “We must not forget that when filtering, apart from water and solid particles, oil is also retained, causing losses to the producer. Also taking into account that acquiring the machinery for filtering causes the expense to increase, it is normal that there is no interest in doing information work explaining the advantages of filtering."
Puntas, for his part, points out. “Unfiltered oil can be an excellent product, full of flavors and nuances, for all those olive oil lovers, but it is important to remember that it is very perishable and must be consumed soon. Its defenders assure that in a tasting it presents many more nuances, although the general opinion of experts is that these are practically imperceptible." The director of the La Patente school declares herself a lover of those unfiltered oils with a “cloudy, rustic and less manipulated appearance”, since they are also always a guarantee that they come from a recent harvest, “something we do not know in the case of filtered extra virgin olive oil.”
