`Study Shows Adding Water Decreases Yield and Quality, Even in Non-Irrigated Olives - Olive Oil Times

Study Shows Adding Water Decreases Yield and Quality, Even in Non-Irrigated Olives

By Costas Vasilopoulos
Apr. 8, 2013 17:26 UTC

Researchers at the Department of Food Technology of the University of Extremadura in Spain have released a new study about the pos­si­ble effects of using addi­tives dur­ing the extrac­tion process of olive oil.

More specif­i­cally, they focused on adding water and talc pow­der dur­ing the malax­a­tion stage of olive oil pro­duc­tion. Adding water dur­ing malax­a­tion is a com­mon method to get more oil out of the paste.

Surprisingly, the added water caused a decrease in oil yield and oil extractabil­ity for both of the cul­ti­vars tested.

Other stud­ies have cau­tioned against adding water when dru­pes are har­vested from irri­gated orchards since they already con­tain enough water inside, but this study sug­gests pro­duc­ers should think twice about adding water to non-irri­gated olives as well.

Free acid­ity was not sig­nif­i­cantly affected by the added water, but the extracted olive oil con­tained reduced phe­nols and a lower antiox­i­dant value.

Meanwhile, the research showed that adding talc dur­ing malax­a­tion can sig­nif­i­cantly improve extractabil­ity and oil yield, an out­come con­sis­tent with the results of pre­vi­ous stud­ies car­ried out on olive fruits of dif­fer­ent cul­ti­vars. There was no impact of the talc addi­tion on free acid­ity, but olive oil color was sig­nif­i­cantly affected, turn­ing greener, bluer and lighter than nor­mal.

For the study, researchers used olive fruits from the Carrasquena and the Picual cul­ti­vars, and processed them with an Abencor lab­o­ra­tory scale sys­tem machine.

The results out­lined in the study could serve as a rec­om­men­da­tion for mill own­ers to rethink the widely-used tech­nique of adding water dur­ing malax­a­tion, and sup­ports the ben­e­fits of the two-phase pro­duc­tion method over the three-phase method. Refraining from adding water can reduce energy con­sump­tion, pro­duc­ing less liq­uid residue and yield olive oil of a bet­ter qual­ity.


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