Omics Ensure the Authenticity of Portuguese Olive Oils

The grow­ing Portuguese olive oil indus­try may add a com­pet­i­tive advan­tage to its prod­ucts thanks to the Portuguese olive oil omics for trace­abil­ity and authen­tic­ity, also known as the Por30 project.

The research effort, which is being led by the University of Évora, aims to ensure the authen­tic­ity and trace­abil­ity of Portuguese oils using genomic and metabolomic approaches that address geo­graph­i­cal and vari­etal aspects and dif­fer­ences of olives across Portugal.

Authenticity and trace­abil­ity are emerg­ing top­ics in food sci­ence. Food authen­ti­ca­tion pro­ce­dures help ensure the authen­tic­ity and ori­gin of food prod­ucts as well as the iden­ti­fi­ca­tion of fraud­u­lent prac­tices. An indus­try chal­lenge is the devel­op­ment of reli­able ana­lyt­i­cal cer­ti­fi­ca­tion tools to meet these objec­tives.

“Genomic and metabolomic approaches are more reli­able than other approaches to authen­ti­cate and trace olive oil,” Maria João Cabrita, from the food sci­ence group of the the University of Évora’s Institute of Mediterranean Agricultural and Environmental Sciences (ICAAM), told Olive Oil Times.

“The metabolomic approach gives us a lot of infor­ma­tion about the chem­i­cal com­po­si­tion of olive oils and we are try­ing to cor­re­late chem­i­cal data with, or explain them, with some vari­ables such as rain, tem­per­a­ture, loca­tion,” she added.

Traditionally, food authen­ti­ca­tion relied on the iden­ti­fi­ca­tion of chem­i­cal marker com­pounds, such as volatile and phe­no­lic com­pounds, toco­pherols, pig­ments, sterols, fatty acids, tri­a­cyl­glyc­erols and sen­so­r­ial analy­sis.

Identification was then fol­lowed by the quan­tifi­ca­tion and com­par­i­son of the obtained val­ues with those estab­lished for gen­uine mate­r­ial. This approach had lim­i­ta­tions and required that tar­get mol­e­cules (mark­ers) were pre­vi­ously iden­ti­fied.

The genomic approach is based on the olive oil DNA eval­u­a­tion, as well as the def­i­n­i­tion of mol­e­c­u­lar mark­ers for each olive vari­ety stud­ied.

The metabolomic approach uses a num­ber of tech­niques, such as pro­fil­ing and fin­ger­print­ing, focus­ing on the study of the volatile com­po­si­tion of oils using com­pre­hen­sive mul­ti­di­men­sional gas chro­matog­ra­phy, as well as the study of min­eral ele­ments using ICP-MS tech­niques.

In addi­tion, the study of sta­ble iso­tope (SIRMS) com­po­si­tion of light ele­ments by iso­tope ratio mass spec­troscopy (IRMS) and the use of nuclear mag­netic res­o­nance spec­troscopy to pro­vide a spec­tral sig­na­ture of the dif­fer­ent fatty acids of mono­va­ri­etal extra vir­gin olive oils are used to iden­tify ori­gin.

These tech­niques are also used to dis­crim­i­nate among other types of extra vir­gin olive oils, such as organic or nonor­ganic.

Portugal is the world’s sev­enth largest pro­ducer of olive oil and the fourth largest olive oil exporter. The coun­try has recently seen its olive grove sur­face expand, impact­ing olive oil pro­duc­tion. Since extra vir­gin olive oil is a high-qual­ity prod­uct eco­nom­i­cally impor­tant for the coun­try, it is imper­a­tive that Portugal has a thor­ough under­stand­ing of its olive vari­eties and oils, to pro­tect the value of their unique­ness.

Alentejo is respon­si­ble for two-thirds of Portugal’s national olive crop and this is why Por30 has focused on this region and some of its most impor­tant olive vari­eties: Galega Vulgar, Carrasquenha, Cordovil de Serpa, Cobrançosa, Blanqueta de Elvas, Madural, and Verdeal Alentejana.

Picual and Arbequina have also been con­sid­ered because of their global rep­u­ta­tion and large pres­ence in Alentejo, where the increase of super-inten­sive cul­ti­va­tion has made these non­tra­di­tional cul­ti­vars gain impor­tance. A deeper knowl­edge of Portuguese olive vari­eties and the olive oils they pro­duce can encour­age the plant­ing of more Portuguese olive vari­eties.

Por30 also stud­ies some oils from Trás-os-Montes, north of Portugal.

“The orig­i­nal idea was to study more regions, but it was not an easy task to obtain the olive oils, since we need vari­etal olive oils,” Cabrita said.

Launched in 2016 and expected to end this October, Por30 is a national project involv­ing Évora and Nova de Lisboa Universities, with some involve­ment of the National Institute of Agrarian and Veterinary Research, which pro­vides assis­tance in olive oil sam­pling.

Samples have been deliv­ered by sev­eral oil pro­duc­ers, although no olive oil Protected Designations of Origin or reg­u­la­tory bod­ies have been engaged in the project.

“Apart from genomic, which is not yet fin­ished, we can say that apply­ing the cor­rect sta­tis­ti­cal tools, the volatile com­po­si­tion of olive oil reflects the vari­etal ori­gin of olive oils,” Cabrita said. ​“They have dif­fer­ent volatile pro­files that can be linked with the vari­eties.”

“Regarding the geo­graphic ori­gin, the iso­topic ratios sig­na­ture of olive oils from the north are dif­fer­ent from the south,” she added, indi­cat­ing that a cer­ti­fi­ca­tion seal is not planned at this moment. ​“We sub­mit­ted an arti­cle that to the best of our knowl­edge is the first report that records and eval­u­ates bulk δ2H [hydro­gen iso­tope] of Portuguese extra vir­gin olive oils.”

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