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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.

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.

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.

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.

• Science Direct
• Umbria 24