Olive Varieties

New Phenolic Compounds Found in EVOO

New phenolic compounds belonging to the oleuropein and ligstroside aglycon family have been discovered in oils from the Koroneiki and Mission olive varieties.

May. 11, 2016
By Jedha Dening

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The Mediterranean diet is the world’s most stud­ied dietary pat­tern and has been shown to pro­vide valu­able health ben­e­fits and reduce the risk of numer­ous dis­eases.

Extra virgin olive oil (EVOO) is the major source of lipids in the Med Diet and is con­sumed on a daily basis. EVOO con­tains pow­er­ful phe­no­lic com­pounds that exert many of these known health ben­e­fits, namely hydrox­y­ty­rosol, tyrosol and their deriv­a­tives.

Understanding the chem­i­cal iden­tity of the var­i­ous phe­no­lic com­pounds is crit­i­cally impor­tant for fur­ther­ing research and for per­mit­ting spe­cific health claims in rela­tion to spe­cific phe­no­lic com­pounds. However, it has been noted that some lit­er­a­ture does not accu­rately define terms and can often be mis­lead­ing, in some cases caus­ing prob­lems in trans­lat­ing results and out­comes. Without a doubt, there are tech­ni­cal dif­fi­cul­ties; how­ever, there is no offi­cially defined method for the mea­sure­ment of phe­no­lic com­pounds, par­tic­u­larly in rela­tion to making health claims, some­thing that the European Union Legislation (EU 432/2012) has recently per­mit­ted.

According to research pub­lished in OLIVAE, key com­pounds in hydrox­y­ty­rosol and tyrosol “are found in olive oil mainly in the ester­i­fied forms of olea­cein (3,4‑DHPEA – EDA) and oleo­can­thal (p‑DHPEA – EDA) as well as oleu­ropein agly­con (3,4‑DHPEA-EA) and ligstro­side agly­con (p‑HPEA-EA), which all have sig­nif­i­cant bio­log­i­cal activ­i­ties.” However, the researchers also sug­gest that in par­tic­u­lar, “oleu­ropein agly­con and ligstro­side agly­con are terms that are not accu­rately defined and are often used in a mis­lead­ing way.” Most notably the con­fu­sion comes from report­ing the var­i­ous com­pli­cated and descrip­tive names, “hydrox­y­lated form, monoalde­hy­dic form, dialde­hy­dic form, hydrated form, open ring, closed ring, car­boxy­lated, decar­boxy­lated” and so forth.

During their research, Panagiotis Diamantakos1, Angeliki Velkou, Brian Killday, Thanasis Gimisis, Eleni Melliou1, and Prokopios Magiatis dis­cov­ered for the first time ever, new olive oil (OO) ingre­di­ents belong­ing to the oleu­ropein and ligstro­side agly­con family. The researchers sug­gest naming the new com­pounds oleoko­ronal, oleomis­sional and ligstro­dial “to min­i­mize the con­fu­sion aris­ing from the use of com­pli­cated or abbre­vi­ated names.”

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To dis­cover the com­pounds, the researchers con­ducted screen­ing of 2,000 vari­eties of OO using NMR analy­sis. To ensure the results were not an arti­fact of the extrac­tion and dilu­tion process, and to prove that they were real ingre­di­ents, the researchers used a EVOO sample with­out any sol­vent and put it through an exci­ta­tion pulse exper­i­ment before com­par­ing it to a diluted form of the same EVOO. The exper­i­ment revealed “the enol form 14 of ligstro­side agly­con” for both EVOO sam­ples, indi­cat­ing that the ingre­di­ents were real.

According to the research, Koroneiki and Mission vari­eties were the first observ­able EVOO vari­eties dis­cov­ered to con­tain oleoko­ronal and oleomis­sional. The authors stated that “in most of the oils stud­ied the con­cen­tra­tion of oleoko­ronal and oleomis­sional and of the related dialde­hy­des was lower than that of oleo­can­thal and olea­cein and in many cases they were totally absent.”

At this stage, it appears that these newly noted phe­no­lics are only present in cer­tain vari­eties, or may be depen­dent on the pro­duc­tion para­me­ters of oils.

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