I would like to clarify a topic that keeps popping up online and has recently come back into the spotlight, probably because we are currently in the production and bottling season: oil to be good, or extra virgin, or from the farmer, it depends on who writes, It does not need to be filtered! Essentially, the idea is being reiterated that for an extra virgin olive oil to be “real” and therefore genuine, not mixed, artificial or industrially processed, it must be cloudy.
Food products and filtration
The simple daily experience of shopping in a store rather than at the market confirms something obvious to us, something we are so accustomed to that we no longer even notice: the products we normally find on sale are cleaned of processing wasteIn fact, almost all commercially available products undergo ordinary filtration (wine, milk, fruit juices) or sifting (flour, sugar), and this also applies to wholemeal or unrefined products. It's important to remember that sifting and filtering serve to remove impurities from the product, that is, those parts that have nothing to do with the product's classification.
This general rule does not seem to apply when purchasing oil because consumers are often offered cloudy extra virgin olive oil, insinuating the idea that it is the real thing or, in any case, better than a filtered one.
What is filtration?
Once the oil has come out of the mill, it must be eliminated little water and particulate matter that remained emulsified in the fluid and that the decanter – however perfect – was unable to separate completely. These processes are called separation and filtration.
In the past, the most common method was natural decantation in tanks, where the oil was placed and left to settle for one or two weeks. As time passed, the oil was gradually removed from the top with special tools, until the sludge settled on the bottom was reached, which was often used to make olive creams or pastes.
Fortunately, today there are tools that do this job in the best possible way in a very short time, avoiding any type of damage to the oil.
Separator – È a sort of vertical centrifuge that separates the oil from the water and processing residues through the high-speed rotation of conical discs, exploiting their different specific gravities.
Filter – The most commonly used system is the panel system: derived from the winemaking industry, it consists of a series of specially shaped plates, usually made of nylon, placed one next to the other to form a sort of packet. Between these are sheets of paper, almost always made of compact cellulose, which have variable porosity. A pump pushes the oil into this packet, freeing it from solid or semi-solid impurities because they are retained by the cardboard, which has pores smaller than the impurities themselves. The residual aqueous phase is also removed thanks to the absorption of the hydrophilic cellulose material.
Why should it be filtered?
Un unfiltered oil, like many other food products, It contains a significant amount of suspended particles which contain aromatic and phenolic substances, but also substances whose oxidizing capacity is directly proportional to the degree of density and therefore of turbidity: The more there are, the faster the oil spoils..
Let me explain with a comparison: if we remove these suspended particles from freshly produced oil and place it on a plate, we'll initially get a pleasant olive aroma. But if we leave it on the plate, it will quickly begin to ferment and become rancid. The same thing happens if we leave it in the oil, meaning we don't filter it: initially, the suspended particles in the oil don't cause problems, but after a few months the cloudy air begins to decompose, conferring organoleptic sensations of fermented, rotten, spoiled olives with hints often halfway between brine and cheese: technically we are in the presence of the sludge defect.
Although some studies have shown that in suspended materials there are phenolic compounds dissolved in a water-oil emulsion and that these are reduced by filtration, it should be remembered that the higher content of polar phase in unfiltered oils exponentially increases the alteration, especially at an inappropriate temperature, mainly influencing free acidity and sensory attributes, making the benefits of suspended polyphenols insignificant over time. Therefore If the oil is consumed within a short time (no more than three/four months after production), in perfect storage conditions no problems arise.; but if it is destined to last longer it is essential to filter it, possibly immediately after production and in any case within a few days, avoiding the artisanal or anachronistic systems I mentioned before.
Must and Novello? No, thanks.
As we all know, advertising relies on puns, often meaningless, that capture the consumer's imagination. In the case of extra virgin olive oil, it seems that it's truly important to season with words rather than with oil. In fact, the cloudy, unfiltered product is often improperly labeled as "extra virgin." must or new oil, two terms stolen from oenology that they have nothing to do with oil: I would rather say that they are antithetical.
The must: It is the product of pressed grapes and represents the beginning of the alcoholic fermentation that is the basis of many drinks and therefore it is not clear how it relates to oil which is solely pressed olives and when fermentation is triggered we are in the presence of serious defects.
The new oil: We know that novello wine is made from the carbonic maceration of certain grapes (not all: in Italy, say sixty) and sold in the same year as the harvest from which it comes; oil, on the other hand, is produced from all existing olive varieties and is usually sold in the year following the harvest.
Filtered oil? Always!
So if you like cloudy oil, go ahead and buy it, but it must be very fresh and consumed very quickly. And the next time you find a bottle of oil with the words "cloudy" on the label, “the bottom is an indicator of authenticity” Ask yourself this question: If I found this writing on a bottle of mineral water or milk, would I buy it? So, ask yourself this simple question, but don't forget to ask yourself a few questions about the product and its manufacturer!
