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Researchers from Spain and Brazil have found that cook­ing veg­eta­bles with extra virgin olive oil can improve the extractabil­ity of their polyphe­nols, increas­ing the amount of the com­pound that is absorbed by the oil.

The study exam­ined the inner work­ings of the tra­di­tional meth­ods of Mediterranean cook­ing, attempt­ing to shed light on how extra virgin olive oil inter­acts with the ingre­di­ents of the local cuisines. Along with polyphe­nols, var­i­ous other bioac­tive com­pounds from the veg­eta­bles were also found to be absorbed by the oil when cooked.

The researchers focused on the sofrito method, a pop­u­lar Mediterranean cook­ing tech­nique for prepar­ing a light sauce with tomato, onion and garlic. Sofrito report­edly con­tains 40 dif­fer­ent phe­no­lic com­pounds and a high con­tent of carotenoids, while its con­sump­tion is asso­ci­ated with reduced car­dio­vas­cu­lar risk and insulin sen­si­tiv­ity.

After the cook­ing process, an analy­sis of the olive oil showed that it was infused with polyphe­nols from the veg­eta­bles in the sofrito sauce; specif­i­cally with narin­genin, fer­ulic acid, quercetin and Z‑isomer carotenoids, none of which are typ­i­cal com­pounds of extra virgin olive oil.

The migra­tion of bioac­tive com­pounds such as polyphe­nols and carotenoids from the tomato to the olive oil also explained the find­ings of pre­vi­ous work of the researchers, which had con­cluded that the spe­cific type of sauce demon­strated increased anti-inflam­ma­tory prop­er­ties.

“In inter­ven­tion nutri­tional stud­ies we have observed that polyphe­nols from toma­toes were better absorbed when the tomato was cooked as a sauce with extra virgin olive oil,” Rosa Maria Lamuela-Raventos, a food sci­ence pro­fes­sor at the University of Barcelona and a researcher at Ciberobn (the research center for obe­sity and nutri­tion of Spain), told Olive Oil Times.

“For this reason, we wanted to eval­u­ate why this was hap­pen­ing, so we per­formed an in vitro assay where we sep­a­rated sofrito in three frac­tions or parts: solid (insol­u­ble part), water frac­tion and oil frac­tion,” she added. “In this paper we observed that some of the polyphe­nols from the tomato, onion and garlic were moving to the oil frac­tion, being more bio-acces­si­ble, so easier to be absorbed.”

Additionally, the researchers noticed that the polyphe­nols in the olive oil were also reduced, by degrad­ing or by migrat­ing to the food matrix.

“There is an exchange of polyphe­nols during cook­ing, some more apolar from veg­eta­bles go to the oil frac­tion, while some from the oil are absorbed by the veg­eta­bles,” Lamuela-Raventos, who was also the main author of the study, said. “However, the tem­per­a­ture is impor­tant while cook­ing, because high tem­per­a­tures over 100 degrees Celsius (212 degrees Fahrenheit) oxi­dized polyphe­nols.”

Having used sci­ence for years to assess the qual­i­ties of dif­fer­ent edi­bles and food ingre­di­ents, Lamuela-Raventos regards the Mediterranean diet as one of the health­i­est.

“[The Mediterranean diet] is one of the health­i­est diets in the world,” she said. “As a sci­en­tist, I observe that the results with the tra­di­tional Mediterranean foods and dishes – such as extra virgin olive oil, sofrito, wine and more – give really very good results in inter­ven­tion nutri­tional stud­ies.”

However, sci­ence and good health are not the only para­me­ters to be taken under con­sid­er­a­tion when it comes to the Mediterranean diet, Lamuela-Raventos added.

“As a con­sumer, I try to follow a Mediterranean diet not only for health rea­sons but also because of the way cook­ing and eating habits with family and friends are good not only for health but also for socia­bil­ity and hap­pi­ness,” she said.

“We are con­tin­u­ing our research about cook­ing with extra virgin olive oil with other food rich in pro­teins such as chicken or in car­bo­hy­drates such as pota­toes,” Lamuela-Raventos added. “We want to eval­u­ate if extra virgin olive oil polyphe­nols are absorbed in these foods while cook­ing.”

The health effects of the Mediterranean diet have been dif­fi­cult to repro­duce in non-Mediterranean pop­u­la­tions, the researchers noted, in all like­li­hood due to the dif­fer­ent cook­ing tech­niques used.

The researchers’ work estab­lished that, apart from con­sum­ing the ingre­di­ents and staple foods of the regime, tra­di­tional cook­ing from the Mediterranean can also play an impor­tant role in taking full advan­tage of the ben­e­fits of the Mediterranean diet.

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• Medical Xpress