La olive harvest is imminent, and with it comes the need to address the issue of oil filtration, especially those produced at the beginning of October.
The first oils are usually richer in organic suspensions and have a high degree of turbidity, containing micronized water, air, proteins, enzymes, pectins and mucilages.
These compounds give the oil a cloudy appearance and can activate oil degradation reactions, due to the aqueous fraction, which could be higher than the 2000 ppm, and the enzymes present.
In general, these enzymes, which may include the Lipoxidase, the catalase, he shyperoxide dismutase andascorbate peroxidase, do not damage olive oil, on the contrary, they can have a protective role against oxidation. However, if not properly managed, they can contribute to turbidity and other unwanted alterations.
“Filtering the oil is therefore important to remove them and improve the stability and quality of the product.” This helps to prevent and improve the stability and preservation of the oil.
The risk of sludge
Enzymes, in the presence of water, create a reactive system, especially if storage temperatures exceed 20-22°C, which often leads to the appearance of abnormal flavors and odors, which can be perceived as real defects. These substances, left in the oil, tend to settle on the bottom of the containers within 25-30 days of milling, forming a residue known as “sludge”.
The dregs can compromise the organoleptic characteristics of the oil, reducing its shelf life (shelf life) and altering the flavor, making it evolve from ripe to oxidized and finally rancid. The amount of dregs can vary depending on the variety of olives, the year and the climatic conditions; rain during the harvest or prolonged drought can affect its formation.
For those who produce small quantities of oil for family consumption, decanting can be an effective solution for removing sludge.
Filtration is a crucial step
However, for larger productions, filtration becomes a crucial step to be performed immediately after obtaining the oil. Filtration techniques vary from the traditional Bari method, which uses cotton, to more advanced methods such as layer filtration, with diatomaceous earth o cartridgeThe latter offer greater speed and better removal of impurities.
The filtered oil, free from solid particles that could oxidize rapidly, has a longer life compared to the unfiltered one. However, the filtration process It can also remove some healthy flavor compounds and antioxidants. present in unfiltered oil and the cost of the process can be higher.
Filtration is generally carried out using membranes, diatomaceous earth or filter papers, which separate solid particles from the oil, making it clearer and more uniform. In recent years, technology has introduced a new generation of filter layers, known as “depth filter layers”.
These layers, composed of cellulose and mixtures of mineral components such as diatomaceous earth (diatomite) and perlite, offer superior performance in the removal of impurities, an example being the K Seitz® series by Perdomini IOC, available in different filtration grades. Depth filter layers combine two mechanisms: the mechanical retention andparticle absorption.
La mechanical retention captures larger solid particles, such as pulp pieces, while adsorption removes smaller impurities such as proteins, enzymes and other organic substances. These particles attach to the surface of the filter layer and are thus removed, improving the clarity and stability of the oil and extending its shelf life.
Although the depth filter layers do not represent a completely new technology, they constitute asignificant evolution in the field of filtration. Developed and perfected over the years, these layers meet the growing need for high-quality extra virgin olive oils.
The combination of cellulose and fine mineral components represents an improvement over previous methods, resulting in clearer and more stable oils. Numerous scientific studies support the effectiveness of depth filter layers, demonstrating how thea combination of advanced materials and modern techniques can significantly improve filtration processes, reducing impurities and prolonging the shelf lifeand filtered products.
In conclusion, Depth filter layers represent a consolidated and scientifically validated technology in the field of olive oil filtration.
Thanks to continuous improvements and innovations, these layers offer ever-increasing effectiveness and efficiency, contributing to the production of very high-quality oils, stable over time and ready for the market.
AIPO Director
Interregional Association
Olive producers
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