At Pacific Sun Farms, we consider filtering to be a key step in protecting the high quality and shelf life of our extra virgin olive oils.
We filter to:
The International Olive Council (IOC) has determined that in order to guarantee durability, extra virgin olive oil needs to have a water content of 0.20% or lower. This can be assessed with a simple lab analysis or at the mill with the proper equipment.
Most olive oils have a water content of 0.40%–0.50% right after they’re made. Thus, something has to be done if a good shelf life from harvest to harvest is expected.
Filtration—a step not practiced by most producers in California—is achieved with rolls and plates of cellulose paper that catch sediments and more importantly, humidity (from the remains of micro-drops of vegetable water).
Traditionally, people racked the oils from one container to another, leaving a layer of sediments behind. This was good practice then—though it’s insufficient to remove humidity. Leaving sediments, waste water, micro-bubbles of air, and often, bacteria, sugars and yeast (in the sediments) will accelerate decomposition through enzymatic reactions and self-oxidation. This translates into a faster decay, which manifests, as time passes by, with the olive oil becoming thicker and more viscous, eventually leaving a greasy mouth-feel.
Filtering also has very positive effects in the tasting profile of extra virgin olive oils, leaving them cleaner and crisper in their texture. Since filtration removes what is not olive oil, perfumes are also sharper and neater. During filtration some polyphenols are lost (7–8%) though these are weaker polyphenols (water-soluble) comparing them with the main ones (fat-soluble), which are receiving a great protection by filtering.
While this next point may not be proof of anything, it is something to consider: the vast majority of winners of European olive oil competitions, as well as winners of the international section of US competitions, are filtered oils.*
In order for filtration to be successful it should be done within 48 hours. After the olive oil exits the decanter and the final separator, we filter as soon as we can. While this is more time- and labor-intensive, we’re convinced it is necessary for reaching the extra virgin olive oil quality we are after.
Read our olive maker’s response to the UC Davis Olive Center report on filtration.
* These are some premium, filtered extra virgin olive oils from Europe that are consistent award winners: Dievole, Altomena, Balduccio, De Carlo, Intini, Caputo, Torre Bianca, Olio della Madonina, Fattoria Ramerino, Laudemio, Franci, Fonte di Foiano, Castillo de Canena, Melgarejo, Marqués de Grignón, Crudo.
From California: Apollo, Katz, Isern & Sons, Saltonstall, Moonshadow, Pacific Sun Farms.