Genotype Plays Significant Role in Fatty Acid Content of Virgin Olive Oil

Researchers from Córdoba and Madrid, in Spain, have iden­ti­fied and mea­sured the main causes of vari­abil­ity in the fatty acid con­tent of vir­gin olive oils.

The study pub­lished in Food Chemistry shows that most dif­fer­ences in vir­gin olive oil fatty acids pro­files are due to the geno­type of the olive cul­ti­vars. Lesser but sig­nif­i­cant vari­abil­ity also comes from the impact of the dif­fer­ent cli­mate con­di­tions.

According to the sci­en­tists, their results will con­tribute to future olive breed­ing pro­grams to obtain cul­ti­vars meant for healthy and high-qual­ity olive oil pro­duc­tion.

“Fatty acids are an essen­tial com­po­nent of olive oil. Looking at them from a health per­spec­tive, the more monoun­sat­u­rated and polyun­sat­u­rated fatty acids are present in olive oil, the more the olive oil is con­sid­ered healthy,” Feliciano Priego Capote, pro­fes­sor of ana­lyt­i­cal chem­istry at the University of Córdoba and co-author of the study, told Olive Oil Times.

The fatty acids pro­file, which mea­sures the pro­por­tions of the dif­fer­ent fatty acids, also impacts olive oil sta­bil­ity. ​“A higher pres­ence of monoun­sat­u­rated fatty acids sug­gests higher sta­bil­ity of olive oil against oxi­da­tion and chem­i­cal alter­ations that can dete­ri­o­rate the olive oil prop­er­ties,” Priego Capote said.

The researchers col­lected vir­gin olive oil sam­ples from 45 cul­ti­vars from three con­sec­u­tive crop years. Another 71 sam­ples from an equal num­ber of cul­ti­vars were gath­ered across two suc­ces­sive sea­sons. All sam­ples came from the World Olive Germplasm Bank in Córdoba.

The researchers eval­u­ated the sig­nif­i­cant dif­fer­ences among the fatty acid sam­ples from dif­fer­ent cul­ti­vars. They also mea­sured how sig­nif­i­cant the vari­a­tion of these fatty acids pro­files was from one sea­son to the next.

“We found that the most sig­nif­i­cant fac­tor [in deter­min­ing olive oil fatty acids pro­file] is the cul­ti­var,” Priego Capote said. ​“We can say that there is a genetic pre­dis­po­si­tion that marks the olive oil’s fatty acids pro­file as a func­tion of the cul­ti­var.”

The geno­type accounted for 56 per­cent of the total mea­sured sam­ple vari­abil­ity.

While pre­vi­ous research sug­gested a mod­est inter­an­nual vari­abil­ity, the Córdoba study reached dif­fer­ent con­clu­sions.

“What we found is that there are sig­nif­i­cant vari­a­tions in the fatty acids pro­file in con­sec­u­tive years,” Priego Capote said. ​“Those can essen­tially be explained by cli­ma­to­log­i­cal con­di­tions.”

A rel­e­vant exam­ple of this effect is the impact of accu­mu­lated pre­cip­i­ta­tion on the vari­abil­ity of fatty acids. The researchers mea­sured pre­cip­i­ta­tion vol­umes from June to October across the dif­fer­ent crop sea­sons, all char­ac­ter­ized by sim­i­lar high tem­per­a­tures.

“Accumulated pre­cip­i­ta­tion has a sig­nif­i­cant effect on the con­cen­tra­tion of monoun­sat­u­rated fatty acids and polyun­sat­u­rated fatty acids,” Priego Capote said. ​“We observed that the lower the vol­ume of accu­mu­lated pre­cip­i­ta­tion in those months, the lower the monoun­sat­u­rated fatty acids found in the sam­ples. Saturated fatty acids and polyun­sat­u­rated fatty acids were instead found in higher con­cen­tra­tion.”

By ana­lyz­ing the dif­fer­ences among sam­ples in the dif­fer­ent years, the study also iden­ti­fied a cul­ti­var-per-crop year effect which impacts 25 per­cent of the total fatty acids vari­abil­ity.

“Essentially, it means that not all cul­ti­vars evolve in the same way through the years, not all respond to the same vari­a­tions in con­sec­u­tive years,” Priego Capote said. ​“For instance, some cul­ti­vars decrease monoun­sat­u­rated fatty acids in their sec­ond crop year while oth­ers increase them. That means that there are addi­tional fac­tors which can affect a par­tic­u­lar cul­ti­var to a greater extent.”

The new research did not specif­i­cally eval­u­ate the envi­ron­men­tal effect on fatty acid vari­abil­ity.

“In pre­vi­ous research, we have seen how the loca­tion of a tree can trig­ger some fatty acids vari­abil­ity,” Priego Capote said. ​“For instance, we have seen that the ele­va­tion above sea level can impact the fatty acids pro­file.”

“The three fac­tors to be con­sid­ered in mea­sur­ing vari­abil­ity are, there­fore, genet­ics, inter­an­nual vari­abil­ity, which is essen­tially linked to cli­mate, and envi­ron­ment,” he added.

By iden­ti­fy­ing how the fatty acids pro­file will change through time, in addi­tion to pre­cise data about olive oil polyphe­nol con­tent, researchers believe it could become eas­ier to pre­dict the dura­bil­ity and sta­bil­ity of the final prod­uct.

“Given their dif­fer­ences, we should prob­a­bly say that not all olive oils should have the same best-before-date,” Priego Capote said.

“In another paper, our team found a for­mula com­bin­ing olive oil’s fatty acids pro­file and phe­no­lic pro­file to pre­dict the Rancimat response, which is a test for the eval­u­a­tion of sta­bil­ity,” he added.