New Production Technology Improves Olive Oil Quality

Tests show that high vacuum-assisted extraction technologies increase polyphenols and lower volatile compounds in extra virgin olive oils. Further tests are needed to understand their impact on yields.
By Paolo DeAndreis
Nov. 23, 2020 07:26 UTC

High vac­uum-assisted extrac­tion tech­nolo­gies improved the healthy char­ac­ter­is­tics of extra vir­gin olive oil while also decreas­ing sen­sory defects, accord­ing to new research from the University of Perugia.

Italian sci­en­tists have found that under cer­tain con­di­tions the polyphe­nol con­tent of the extra vir­gin olive oil can be increased up to 48 per­cent when using the high vac­uum-assisted extrac­tion tech­nolo­gies.

We have noticed an increase in the phe­no­lic com­pounds that var­ied approx­i­mately between 20 and 48 per­cent.- Gianluca Veneziani, researcher, University of Perugia

A reduc­tion in the con­tent of volatile com­pounds, which are respon­si­ble for cre­at­ing fla­vor defects in olive oils, was also observed.

Our exper­i­ments in the first phase of the research brought us to eval­u­ate the impact of the high vac­uum-assisted extrac­tion on both the sen­so­r­ial pro­file and the health prop­er­ties pro­file of olive paste and oil,” Gianluca Veneziani, a researcher at the uni­ver­sity and one of the authors of the study told Olive Oil Times.

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The research, pub­lished in the jour­nal Food Chemistry, was con­ducted using three dif­fer­ent cul­ti­vars – Moraiolo, Coratina and Peranzana – and showed dif­fer­ent results for each one of the cul­ti­vars.

We have noticed an increase in the phe­no­lic com­pounds that var­ied approx­i­mately between 20 and 48 per­cent,” Veneziani said. As our team noted in a pre­vi­ous study when you intro­duce a tech­nol­ogy that it is going to inter­vene on the cel­lu­lar struc­ture of a fruit, the out­come is heav­ily depen­dent on its own genet­ics.”

He added that while some cul­ti­vars might already tend to pro­duce high quan­ti­ties of polyphe­nols, some oth­ers might enjoy a lit­tle help” in reach­ing those high lev­els. Elevated lev­els of polyphe­nols are gen­er­ally asso­ci­ated with high-qual­ity extra vir­gin olive oil.

The other goal of the study was to observe the impact of the high vac­uum-assisted extrac­tion tech­nolo­gies on the con­tent of volatile com­pounds, a cru­cial aspect of the research due to the impact of these com­pounds on the fla­vor and qual­ity of extra vir­gin olive oil.

The researchers found that lower tem­per­a­tures dur­ing malax­a­tion led to a low­ered strip­ping effi­ciency in the extract­ing process. This means that the com­pounds respon­si­ble for neg­a­tively affect­ing the fla­vor of the extra vir­gin olive oil decreased as a func­tion of lower oper­at­ing tem­per­a­tures.

We also observed the reduc­tion of some volatile mol­e­cules we could con­sider neg­a­tive, such as ethanol, ethyl acetate and acetic acid,” Veneziani said. Those are respon­si­ble for minor defects of olive oil but the strip­ping of these spe­cific mol­e­cules has shown to be very effi­cient, reduc­ing them much more than what might hap­pen to pos­i­tive con­tents. A result that is prob­a­bly due to the cel­lu­lar struc­ture of those com­pounds.”

Veneziani added that the dif­fer­ent behav­iors from each of the three dif­fer­ent cul­ti­vars was attrib­uted to their dif­fer­ent genet­ics.

When lower tem­per­a­tures are engaged, some cul­ti­vars might see more strip­ping effects than oth­ers,” he said.

With the coop­er­a­tion of the research team of the Scuola Sant’Anna in Pisa, Tuscany, the sci­en­tists noted how the high vac­uum sys­tem favor­ably impacted the behav­ior of the olive cells in the malax­a­tion phase.

We have com­pared what was hap­pen­ing there to what usu­ally hap­pens with con­ven­tional malax­ing,” Veneziani said.

We dis­cov­ered that high vac­uum tech­nolo­gies tend to increase the intra­cel­lu­lar flow in the olive paste,” he added, hint­ing at the effects on the mechan­i­cal and struc­tural prop­er­ties of the olive cells.


As a result of the cryo-scan­ning elec­tron microscopy analy­sis, Veneziani con­tin­ued, we found that the olive oil micro-drops tend to get big­ger, as an increase in coa­les­cence can be noted.”

That increase might have a direct impact on the decanter effi­ciency and on the final olive oil yield.

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The study came about as the result of a part­ner­ship between the University of Perugia and Alfa Laval, a major inter­na­tional pro­cess­ing equip­ment pro­ducer.

However, the results of the study will have no imme­di­ate impact on the type of pro­duc­tion equip­ment avail­able on the mar­ket, though researchers con­sider it a promis­ing first step.

Our next step will be to scale up the exper­i­ment and bring our obser­va­tions to real life indus­trial pro­cess­ing oper­a­tions,” Veneziani said.

What the sci­en­tists need to assess is the impact of the new processes on the final olive oil yield. They also intend to bet­ter under­stand the behav­ior of the dif­fer­ent olive cul­ti­vars in the new envi­ron­ment since rel­e­vant dif­fer­ences sur­faced dur­ing the lab test.

Investigating the effects of the new processes on a larger num­ber of cul­ti­vars could even­tu­ally play an impor­tant role in bring­ing the new high-vac­uum extrac­tion tech­nolo­gies to the mar­ket.

What we shall also have to con­firm is the impact on both the phe­no­lic con­tent and volatile com­pounds, specif­i­cally focus­ing on the strip­ping of those mol­e­cules that do usu­ally play a role in dam­ag­ing the olive oil over time,” Veneziani said.


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