Study Finds Olives Grown at Higher Altitudes Yield Better Quality Oils

Summary

A study by Jerash University in Jordan found that olives grown at higher ele­va­tions pro­duce higher qual­ity oils than those grown at lower ele­va­tions, with oils from the Kufranja area hav­ing the best qual­ity and longest stor­age abil­ity. The research showed that cli­matic con­di­tions, post-har­vest pro­ce­dures, and weather all play a sig­nif­i­cant role in deter­min­ing olive oil qual­ity, sug­gest­ing that future olive groves should be planted at higher ele­va­tions for bet­ter qual­ity oils.

A recent study by Jerash University, in Jordan, has found that olives cul­ti­vated at higher ele­va­tions yield higher qual­ity oils that those cul­ti­vated at lower ele­va­tions.

The researchers com­pared oils pro­duced at 750 feet below sea level, in the Jordan Valley, with those pro­duced at 1,600, 2,230 and 2,580 meters above sea level in Al-Subaihi, Kufaranja and Madaba, respec­tively.

Al-Shdiefat and his team looked at the val­ues of 13 dif­fer­ent fatty acids from 12 sam­ples, three of which were pro­vided by each of the four regions. The oils used in the study all came from non-irri­gated farms, were har­vested in early November and stored in the exact same con­di­tions until the study could be done.

What they found was that oils pro­duced from olives grown at higher ele­va­tion tended to have higher ratios of unsat­u­rated to sat­u­rated fatty acids, espe­cially oleic acid, which is con­sid­ered the main and most impor­tant acid in olive oil com­po­si­tion.

“High ele­va­tion olive oil, such as that from the Kufranja area, is of good qual­ity and is char­ac­ter­ized by long con­ser­va­tion and stor­age peri­ods as com­pared with other oils, thus pre­serv­ing its phys­i­cal and chem­i­cal prop­er­ties and high nutri­tional value,” Saleh Al-Shdiefat, a pro­fes­sor in the depart­ment of agri­cul­ture at Jerash University, wrote in the study.

The only anom­aly in the study was that oils from the slightly lower Kufaranja region (2,230 feet) had higher val­ues of unsat­u­rated fatty acids that the Madaba region (2,580 feet).

“Mainly the cli­matic con­di­tions, espe­cially tem­per­a­ture, light expo­sure and pre­cip­i­ta­tion, in addi­tion to the cul­tural prac­tices and post har­vest pro­ce­dures until press­ing in the mills [accounted for this anom­aly],” Al-Shdiefat told Olive Oil Times.

In other words, the weather and har­vest­ing prac­tices also have a sig­nif­i­cant impact in deter­min­ing olive oil qual­ity, but when the best prac­tices are applied to higher ele­va­tion groves and the weather coop­er­ates with grow­ers, the result­ing oils are of a higher qual­ity.

Meanwhile, oils pro­duced from olives grown in the Jordan Valley had the low­est ratios of unsat­u­rated to sat­u­rated fatty acids, but had the high­est lev­els of linoleic and linolenic fatty acids, which con­tribute to the fla­vor of the olives and are prefer­able in table olives.

“While olive oil pro­duced below sea level, such as in the Jordan Valley area, is the most desir­able oil on the table, it has the low­est qual­ity of the four sites, and it is the most vul­ner­a­ble to oxi­da­tion and has low stor­age abil­ity,” Al-Shdiefat wrote.

Al-Shdiefat said that the find­ings from his study should be used to deter­mined where future olive groves should be planted and what cur­rent groves should be used for, whether it be table olives or the pro­duc­tion of olive oils des­tined for export.

“Taking the out­put results con­cern­ing qual­ity issues into con­sid­er­a­tion, it is prefer­able not to plant more olive trees in the Jordan Valley areas,” he said.

Olive cul­ti­va­tion and oil pro­duc­tion are the most impor­tant agri­cul­tural activ­i­ties in Jordan and pro­vides liveli­hoods for Jordanian liv­ing in rural areas. Roughly 24 per­cent of Jordan’s arable land is planted with olive trees and the sec­tor has received sig­nif­i­cant invest­ment both domes­ti­cally and from abroad over the past decade.

According to the International Olive Council, Jordan pro­duced 24,000 tons of olive oil in the 2018/19 cam­paign, of which 1,000 tons were exported. The king­dom also pro­duced 30,000 tons of table olives in the cam­paign, of which 5,000 tons were exported.

“In Jordan, we are look­ing to improve olive and olive oil qual­ity,” Al-Shdiefat said.

This means find­ing the best places to plant new olive trees, so that the result­ing oils will have the high­est pos­si­ble qual­ity chem­i­cal com­po­si­tions. Based on the results of this study, that means shift­ing cul­ti­va­tion away from the lower ele­va­tions and look­ing for new places to cul­ti­vate olives out­side of the west and north­east of the coun­try, where olives have been tra­di­tion­ally grown for mil­len­nia.

“This research is the start­ing point of this issue.” Al-Shdiefat said. ​“We need to be look­ing for other ele­va­tions more than 1,000 meters [3,280 feet] above sea level that are found in the south­ern part of Jordan [to see if olives can be grown suc­cess­fully there].”

The study was pub­lished by the Canadian Center of Science and Education.

• Canadian Center of Science and Education