Filtered or Unfiltered Olive Oil? A Choice for Consumers

Olive oil pro­duc­tion is the process of extract­ing the oil con­tained in olive dru­pes and involves a sequence of stages in a mill.

After the olives are har­vested, they are trans­ported to the mill, washed and crushed into a thick paste, which under­goes a process called malax­a­tion (or knead­ing). Malaxation is a crit­i­cal stage that allows the oil droplets to com­bine and form larger droplets.

Then the paste is fed to a cen­trifuge which spins the paste to sep­a­rate the oil from the fruit flesh, pits and water.

Finally, the result­ing olive oil is passed on to a smaller cen­trifuge machine – the sep­a­ra­tor – which removes most of the remain­ing water and sus­pended solids in the oil.

Thus, olive oil is born. If it ful­fills spe­cific qual­ity and sen­sory cri­te­ria, it is clas­si­fied as extra vir­gin, com­pris­ing all the health ben­e­fits that olive oil of the high­est qual­ity pro­vides.

After the trans­for­ma­tion process is com­pleted, there are two paths for pro­duc­ers to choose from to get their olive oil to mar­ket.

They can bot­tle the olive oil as is, unfil­tered. The other option is to fil­ter or rack the olive oil, depend­ing on the tech­nique applied. Filtration (or rack­ing) removes any remain­ing solid par­ti­cles and mois­ture.

The first appar­ent dif­fer­ence between fil­tered and unfil­tered olive oil is appear­ance: unfil­tered olive oil is opaque and cloudy due to the solid resid­u­als present in the oil, while fil­tered olive oil is brighter and more trans­par­ent, free of impu­ri­ties.

Olive oil fil­tra­tion is an impor­tant stage of olive oil pro­duc­tion in its own right.

The International Olive Council (IOC), the inter­gov­ern­men­tal orga­ni­za­tion of olive oil-pro­duc­ing nations, rec­om­mends that olive oil undergo fil­tra­tion to remove any solid micropar­ti­cles and water, increas­ing the oil’s shelf life.

Most com­mer­cially avail­able extra vir­gin olive oils are fil­tered.

Unfiltered olive oil, also known as cloudy, veiled or olio nuovo, is avail­able in smaller quan­ti­ties and is appre­ci­ated by some con­sumers who believe that it packs a richer fla­vor and aroma and bet­ter retains its polyphe­nols than its fil­tered coun­ter­part.

Polyphenols are a type of bioac­tive com­pound present in olive oil (and par­tic­u­larly in extra vir­gin olive oil) that are respon­si­ble for many of olive oil’s health ben­e­fits. This is why some con­sumers seek high-polyphe­nol (or high-phe­no­lic) extra vir­gin olive oils.

There is no defin­i­tive norm among olive oil pro­duc­ers when it comes to fil­tra­tion. Some do not fil­ter their olive oils, while oth­ers take the extra step to obtain a clearer end prod­uct.

Filtering results in clearer fla­vor and aro­mas to the oil, has a min­i­mal effect on the con­tent of polyphe­nols and other ben­e­fi­cial com­pounds, and extends the oil’s shelf life.

Eleftheria Kasfiki, an export man­ager at Olico Brokers, a bot­tling and export­ing com­pany based in Athens, says fil­ter­ing is essen­tial and pre­serves extra vir­gin olive oil and all of its qual­i­ties.

Kasfiki dis­agrees that olive oil retains its organolep­tic char­ac­ter­is­tics when left unfil­tered since sed­i­ment con­sist­ing of olive pulp par­ti­cles, mois­ture and mar­garines – byprod­ucts cre­ated dur­ing the fer­men­ta­tion of the olive oil in the bot­tle – grad­u­ally form at the bot­tom of the bot­tle, alter­ing the fla­vor and reduc­ing the shelf life of the oil.

She added that olive oil fil­ter­ing, espe­cially when pro­duc­ing extra vir­gin olive oil, is a demand­ing process that requires invest­ments in equip­ment and exper­tise to be done effec­tively.

“Olive oil fil­ter­ing removes the mois­ture and any remain­ing resid­u­als in the oil, mak­ing it clear and ready for con­sump­tion,” Kasfiki says. ​“Only in the case of early-har­vested extra vir­gin olive oil (olio nov­ello), which is avail­able to con­sumers for a short period of about three months each sea­son, fil­ter­ing is eschewed.”

According to Matia Barciulli, an Italian chef and olive oil enthu­si­ast, some con­sumers’ pref­er­ence for unfil­tered olive oil is a rem­nant of the past.

“The mind goes back to the time when all the pro­duc­tion process was so arti­sanal, and the only oppor­tu­nity for fil­ter­ing was a sur­face sep­a­ra­tion, with all the fer­men­ta­tion that process acti­vated,” he said.

“We should­n’t be debat­ing on olive oil fil­ter­ing in our time,” Barciulli added. ​“It is easy to under­stand that food which is meant to be kept for a long time must be as clean as pos­si­ble, fil­tered, and stored in steel con­tain­ers.”

“Many times, I walk into a super­mar­ket, and I see peo­ple look­ing at this hor­ri­ble trans­par­ent bot­tle of olive oil with a cen­time­ter of brown mass at the bot­tom,” he con­tin­ued. ​“I explain to them that what they have is a bot­tle of ran­cid oil with some unwanted fla­vors trapped inside.”

Largely speak­ing, fil­tered olive oil is more appeal­ing to con­sumers than unfil­tered oil due to its clar­ity.

Filtered olive oil also boasts a longer shelf life; unfil­tered olive oil is more prone to the effect of heat and light and should be con­sumed more quickly than fil­tered extra vir­gin olive oil.

Unfiltered olive oil is often sought by nos­tal­gic shop­pers look­ing for freshly-milled olive oil to be con­sumed imme­di­ately or within a cou­ple of months.

The dif­fer­ence in nutri­tional ingre­di­ents (such as polyphe­nols) between fil­tered and unfil­tered olive oil is neg­li­gi­ble. After all, the polyphe­nol con­tent in olive oil mostly cor­re­sponds to the vari­ety and ori­gin of olives and proper pro­cess­ing at the mill, rather than the fil­tra­tion process.

In any case, choos­ing a fil­tered or an unfil­tered extra vir­gin olive oil is a mat­ter of taste and per­sonal pref­er­ence.

When olive oil fil­ter­ing is done prop­erly and in a timely man­ner, the results can be reward­ing for pro­duc­ers and con­sumers alike.