What You Didn't Know About Olive Pomace Oil: Uses, Benefits and Controversies

Olive oil ter­mi­nol­ogy is con­fus­ing.

Supermarkets are full of olive oil bot­tles embla­zoned with all sorts of mean­ing­ful (extra vir­gin, vir­gin, early har­vest, organic) – and mean­ing­less (light, pure, ultra-pre­mium) pre­fixes.

However, one cat­e­gory of olive oil increas­ingly stands out in a mar­ket where prices hover near record highs in much of the world: olive pomace oil.

Olive pomace oil, occa­sion­ally referred to incor­rectly as pomace olive oil, sits at the bot­tom of the hier­ar­chy of olive oil grades. It is pro­duced from the byprod­ucts of the vir­gin and extra vir­gin olive oil pro­duc­tion process using chem­i­cal sol­vents and heat.

This process yields crude olive pomace oil, which is unfit for human con­sump­tion and must be treated into refined olive pomace oil and usu­ally blended with vir­gin or extra vir­gin olive oil to become olive pomace oil. (Even the offi­cial nomen­cla­tures are con­fus­ing.)

The Codex Alimentarius, a col­lec­tion of inter­na­tion­ally rec­og­nized food stan­dards, says refined olive pomace oil must be made using meth­ods that do not alter the ini­tial glyc­eridic struc­ture and have a free acid­ity, expressed as oleic acid, of less than 0.3 grams per 100 grams.

Meanwhile, olive pomace oil must have free acid­ity, expressed as oleic acid, less than or equal to one gram per 100 grams, or 1.0%.

The grade is far infe­rior – in terms of fla­vor and health ben­e­fits – to vir­gin and extra vir­gin olive oil. However, a grow­ing body of research demon­strates that it is bet­ter than some other edi­ble oils.

The grade is demo­nized due to its use by some unscrupu­lous actors who exploit cheaply made olive pomace oil to adul­ter­ate extra vir­gin olive oil and sell it at a steep profit.

While its use in fraud is a prob­lem, the olive pomace oil grade fills a valu­able niche in the olive oil world due to its health ben­e­fits (com­pared to other edi­ble oils) and culi­nary appli­ca­tions.

How olive pomace oil is pro­duced

Olive pomace oil is obtained from the wet fatty pomace paste, the main byprod­uct of the olive oil pro­duc­tion process.

During the milling process to make vir­gin or extra vir­gin olive oil, the olives are crushed into a thick paste, which is kneaded in a malaxer to aggre­gate the drops of oil before being cen­trifuged to sep­a­rate the oil from the rest of the olive mate­r­ial, known as olive pomace paste.

The olive pomace paste, which includes water, skin, olive pits and some olive oil, makes up 80 to 90 per­cent of the mass of the milled olives.

Many pro­duc­ers col­lect the olive pomace paste after pro­duc­tion to sep­a­rate the remain­ing oil, rep­re­sent­ing five to eight per­cent of the total olive oil yield.

If the olive pomace paste is not sent to be extracted and refined, pro­duc­ers must pay to have it removed and dis­posed of since it can be toxic to soil and water in indus­trial quan­ti­ties. In small quan­ti­ties, it can be spread in the olive groves and degrade nat­u­rally.

The paste is taken to an extrac­tion plant, where it is dried and sep­a­rated into dry fatty pomace, bio­mass and steam.

The fatty pomace, which is dried into pow­der and pressed in pel­lets, is show­ered in a chem­i­cal sol­vent, usu­ally hexane, which dis­solves the fats but not the rest of the solid pomace. The mix­ture of fats and sol­vent is then heated from 60 ºC to 90 ºC until the sol­vent evap­o­rates.

This is the same method used to pro­duce most other edi­ble oils, includ­ing canola, sun­flower and soy­bean.

The result is crude olive pomace oil, which is unsafe for human con­sump­tion and must be processed into refined olive pomace oil.

The refin­ing process includes sev­eral steps, start­ing with set­tling.

In this step, the recently lib­er­ated crude olive pomace oil is left in tanks for a min­i­mum of four weeks to allow any remain­ing water, sed­i­ment, impu­ri­ties or waxes to set­tle at the bot­tom of the tank and be drained out.

After set­tling, the remain­ing crude olive pomace oil still retains unde­sir­able sub­stances, includ­ing free fatty acids and phos­phatides and must be neu­tral­ized to remove them.

Neutralization, also called purifi­ca­tion, involves cen­trifug­ing the set­tled crude olive pomace oil while adding steam and phos­phoric acid to remove phos­phatides and other impu­ri­ties.

After neu­tral­iza­tion, the crude olive pomace oil is cold-fil­tered using water and caus­tic soda to elim­i­nate alco­hol that clouds the oil at low tem­per­a­tures. This phase, known as win­ter­i­za­tion, pro­duces clear and shiny oil.

Next, the crude olive pomace oil is dehy­drated to remove the water added in the pre­vi­ous two steps, and then the oil is car­bon-fil­tered to remove its pig­ments. The process can also remove harm­ful com­pounds that may have formed in the oil dur­ing neu­tral­iza­tion, such as poly­cyclic aro­matic hydro­car­bons and ben­zopy­renes.

After it is dis­col­ored, the crude olive pomace oil is deodor­ized to remove free fatty acids and sub­stances that give the oil an odor or fla­vor by inject­ing steam in a high-pres­sure vac­uum. After, the oil is fil­tered once again.

Refined olive pomace oil, now fit for human con­sump­tion, is taken to a bot­tling plant and usu­ally blended with vir­gin or extra vir­gin olive oil to add fla­vor and aroma.

The poten­tial dan­ger of the olive pomace oil pro­duc­tion process

Heat plays a fun­da­men­tal role in pro­duc­ing olive pomace oil. However, the tem­per­a­ture must be kept below 90 ºC to pre­vent the pro­duc­tion of dan­ger­ous chem­i­cals that can harm human health.

If the tem­per­a­ture is not reg­u­lated, the refin­ing process can cre­ate poly­cyclic aro­matic hydro­car­bons (PAHs), includ­ing ben­zopy­rene, which research has shown to be highly car­cino­genic and muta­genic.

The risk of ben­zopy­rene con­t­a­m­i­na­tion occurs when the heat­ing method used to evap­o­rate the sol­vent exceeds 300 ºC.

In these instances, the fat is liq­ue­fied and drips out of the olive pomace. However, the extremely high heat results in the par­tial com­bus­tion of the oil, caus­ing the rapid accu­mu­la­tion of ben­zopy­renes in the final prod­uct.

Benzopyrenes, which are highly reac­tive, can dis­solve eas­ily into cel­lu­lar mem­branes and enter a cell’s inte­rior.

This result­ing action has been shown to cause either intra­cel­lu­lar oxi­da­tion – the aging and death of cells – or intox­i­ca­tion, which results in the muta­ge­n­e­sis of the genetic mate­r­ial in the cell’s nucleus.

In some instances, this spreads as an uncon­trolled mul­ti­pli­ca­tion of dam­aged cells, which can result in a can­cer­ous tumor.

As a result, spe­cific stan­dards have been set in var­i­ous regions of the world lim­it­ing the allow­able amount of ben­zopy­renes in olive pomace oil.

Within the European Union and mem­ber states of the International Olive Council, the limit is two parts per bil­lion or two micro­grams per kilo­gram, as decided in Resolution RES‑1/93-IV/05 Madrid in November of 2005.

Health ben­e­fits of olive pomace oil

If olive pomace oil is pro­duced cor­rectly, its con­sump­tion pro­vides health ben­e­fits com­pared to other com­mon edi­ble oils.

While the refin­ing process removes the vast major­ity of the phe­no­lic com­pounds – which are respon­si­ble for most of the health ben­e­fits asso­ci­ated with extra vir­gin olive oil – a grow­ing body of research demon­strates that there are still ben­e­fits to olive pomace oil con­sump­tion.

Like vir­gin and extra vir­gin olive oil, 75 per­cent of olive pomace oil is com­prised of monoun­sat­u­rated fatty acids.

All types of fats help the body absorb vit­a­mins and min­er­als, build cell mem­branes and are essen­tial for the mech­a­nisms that cause blood clot­ting, mus­cle move­ment and inflam­ma­tion.

However, stud­ies have demon­strated that monoun­sat­u­rated fats lower LDL cho­les­terol, also known as ​“bad cho­les­terol,” lead­ing to a lower risk of heart dis­ease and stroke.

Up to 85 per­cent of monoun­sat­u­rated fatty acids in olive pomace oil are oleic acid, an omega‑9 fatty acid.

An exten­sive body of research has found oleic acid con­sump­tion to be asso­ci­ated with the pre­ven­tion of dif­fer­ent types of dis­or­ders, such as car­dio­vas­cu­lar or autoim­mune dis­eases, meta­bolic dis­tur­bances, skin injury and can­cer.

A four-year study pub­lished in 2022 by the Institute of Food Science and Technology and Nutrition in Spain found that olive pomace oil con­sump­tion improved car­diometa­bolic risk bio­mark­ers in healthy and high-cho­les­terol patients.

Specifically, the con­sump­tion of olive pomace oil reduced para­me­ters related to cho­les­terol, waist cir­cum­fer­ence and lipid oxi­da­tion.

The researchers also found that olive pomace oil con­sump­tion pos­i­tively affected insulin resis­tance and sen­si­tiv­ity, sug­gest­ing its con­sump­tion could lead to a lower risk of type 2 dia­betes.

Additionally, olive pomace oil does retain some polyphe­nols. While its con­sump­tion does not pro­vide any­where near the same ben­e­fits asso­ci­ated with extra vir­gin olive oil, it is a healthy alter­na­tive to other edi­ble oils.

Culinary uses of olive pomace oil

The com­bi­na­tion of a neu­tral fla­vor, high smoke point (240 ºC), asso­ci­ated health ben­e­fits and lower price com­pared to vir­gin or extra vir­gin olive oil make olive pomace oil ideal for a range of culi­nary appli­ca­tions.

Recent research from Spain’s Instituto de la Grasa, or Fat Institute, found olive pomace oil to be a supe­rior ingre­di­ent in bak­ery prod­ucts.

Researchers replaced the sun­flower oil in tra­di­tional cup­cake and torta recipes with olive pomace oil. They found the sub­sti­tu­tion did not dimin­ish the taste of the baked goods while increas­ing their shelf life and improv­ing their health pro­files.

A sep­a­rate study from the Institute of Food Science and Technology and Nutrition found mar­garine made from olive pomace oil to be an ade­quate sub­sti­tute for but­ter in puffy pas­try, such as vol-au-vents, crois­sants, crodots and palmiers.

Pastries made from olive pomace oil-based mar­garine had 25 to 37 per­cent less sat­u­rated fat con­tent than but­ter. At the same time, pan­elists found no dif­fer­ences in sen­sory attrib­utes between the two types of pas­tries and a min­i­mal dif­fer­ence in tex­ture.

Along with bak­ing, olive pomace oil is also an excel­lent choice for deep fry­ing. Olive pomace oil is health­ier than other com­mon deep fry­ing oils, with research indi­cat­ing it passes along some health ben­e­fits to fried food and is a more afford­able (though less healthy) option than vir­gin or extra vir­gin olive oil.

A 2021 study pub­lished by researchers from the Instituto de la Grasa found that fry­ing food in olive pomace oil improved its fatty acid pro­file and enriched it with antiox­i­dant com­pounds com­pared to other types of edi­ble oil.

Analysis of the oil after fry­ing also found the level of polar com­pounds, asso­ci­ated with neg­a­tive health con­se­quences, was 25 per­cent below those set by Spanish law.

Further research from the Food and Nutrition Science and Technology Institute found olive pomace oil out­per­forms sun­flower and high oleic sun­flower oil for deep fry­ing pota­toes.

Due to its high per­cent­age of oleic acid and bioac­tive com­pounds, includ­ing squa­lene and beta-sitos­terol, researchers said olive pomace oil was more sta­ble for deep fry­ing over extended peri­ods both in domes­tic and com­mer­cial set­tings, with tasters rat­ing the fla­vor, tex­ture and appear­ance as supe­rior to that of sun­flower and high oleic sun­flower oil.

Final thoughts

Olive pomace oil is a widely mis­un­der­stood cat­e­gory of olive oil.

Unlike vir­gin and extra vir­gin olive oil, it is obtained using heat and chem­i­cal meth­ods. As a result, it lacks the organolep­tic qual­i­ties and health ben­e­fits of the high­est olive oil cat­e­gories.

Still, there is a place for olive pomace oil. It is cheaper than vir­gin or extra vir­gin olive oil and health­ier than other edi­ble oils and but­ter.

When pro­duced cor­rectly, olive pomace oil is bet­ter for bak­ing and fry­ing than many alter­na­tives.

• InfoAgro