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The most healthy com­pounds found in extra vir­gin olive oil do not dis­ap­pear when the oil is used for cook­ing, accord­ing to new research pub­lished in the sci­en­tific jour­nal, Antioxidants. The impli­ca­tion may have an impact on future nutri­tional guidelines.

Researchers from the University of Barcelona focused on eval­u­at­ing how the attrib­utes of olive oil change when it is used for sautéing in a house­hold kitchen.

While the health prop­er­ties in raw extra vir­gin olive oil are well known, its qual­i­ties and char­ac­ter­is­tics when used for cook­ing have sel­dom been investigated.

New evi­dence from the study showed that the polyphe­nols do not dis­ap­pear in the process of being cooked. The antiox­i­dant qual­i­ties were some­what reduced, but still met the European cri­te­ria for healthy food.

Along with their col­leagues in Madrid and São Paulo, the Barcelona-based researchers stud­ied extra vir­gin olive oils, sautéed it at 120 and 170°C (250 and 340°F).

The con­tent of polyphe­nols decreased by 40 per­cent at 120°C and 75 per­cent at 170°C — to lev­els of antiox­i­dants that still qual­ify the oil as healthy under European Union stan­dards, Julián Lozano Castellón, the project coor­di­na­tor, told Olive Oil Times. ​“We decided to do the exper­i­ment with those two tem­per­a­tures because they are usu­ally the low­est and the high­est tem­per­a­tures used in a domes­tic sauté process.”

Interestingly to the researchers, cook­ing the olive oil for a longer time did not sub­stan­tially change the outcome.

“It did not affect the total amount of phe­nols,” Lozano Castellón said. ​“It is true that some sim­ple phe­nols were affected by this vari­able, such as hydrox­y­ty­rosol or hydrox­y­oleu­ropein agly­cone, whose con­cen­tra­tion did decrease with longer cook­ing times.”

However, the researcher high­lighted that the results came from short cook­ing times of less than one hour.

“Normal cook­ing times are short — in our study, the longest time was 60 min­utes — which chem­i­cally is a really short period of time,” Lozano Castellón said. ​“If some phe­no­lic com­pounds were affected by time [exposed to the heat], it means those com­pounds are very labile, even though the pro­por­tion in which time affected those com­pounds was small com­pared to the effect of the temperature.”

The research con­firmed the result of pre­vi­ous stud­ies, which have found extra vir­gin olive oil to be the safest veg­etable oil with which to cook at high tem­per­a­tures and helps absorb the phe­no­lic com­pounds found in veg­eta­bles when cooked together.

“Extra vir­gin olive oil is not only rec­om­mended for its fatty acid pro­file, but also for its more than 200 minor com­po­nents, many of them with antiox­i­dants prop­er­ties,” Lozano Castellón said. 

“In this study, we proved that after cook­ing at a mod­er­ate tem­per­a­ture, those minor com­po­nents were still in the oil and in con­cen­tra­tions high enough to meet the E.U. para­me­ters, mean­ing this oil should be used for cooking.”

• Antioxidants


• University of Barcelona