Adding Water During Olive Oil Production Lowers Quality, Researchers Find

Arbequina extra virgin olive oil produced without added water had higher levels of polyphenol and better oxidative stability than oils produced with added water.
By Paolo DeAndreis
Jul. 18, 2022 16:12 UTC

New research pub­lished in Food Chemistry has con­firmed that adding water dur­ing the olive oil extrac­tion process can pro­foundly affect extra vir­gin olive oil qual­ity.

A team of Portuguese sci­en­tists eval­u­ated what hap­pens when water is added to the olive oil pro­duc­tion process using Arbequina olives, one of the most widely grown olive tree cul­ti­vars in the Iberian penin­sula.

They found sig­nif­i­cant dif­fer­ences in the water-added extra vir­gin olive oil com­pared to the same batch of olives processed with no water addi­tion. The olives trans­formed with­out adding water had higher lev­els of polyphe­nols in the result­ing oil and were far more resilient to oxi­da­tion.

See Also:Spanish Study Suggests More Effective Way to Transform Cold-Stored Olives

The researchers ana­lyzed the chem­i­cal and sen­sory pro­file of Arbequina olive oil extrac­tion in sev­eral set­tings: from no water added dur­ing the pro­duc­tion process to a max­i­mum of 6.2 per­cent of water added for every kilo­gram of processed olives.

In all cases, with or with­out water, the result­ing olive oils were clas­si­fied as extra vir­gin olive oil, accord­ing to the International Olive Council stan­dard.

Despite the extra vir­gin olive oil clas­si­fi­ca­tion, com­pared with the water incor­po­ra­tion… extrac­tion with­out water addi­tion resulted in [olive] oils that showed less pri­mary oxi­da­tion (lower per­ox­ide val­ues and K232), greater total phe­no­lic con­tent (+12 to 22 per­cent) and higher oxida­tive sta­bil­ity (+22 to 31 per­cent),” the researchers wrote.

Additionally, olive oil pro­duced with­out added water had a 5 to 13-per­cent higher sec­oiri­doid con­tent, mainly com­pris­ing olea­cein, a pow­er­ful antiox­i­dant.

As a result, olives trans­formed with­out any added water pro­duced an oil with a more intense ripe fruity sen­sa­tion.

The researchers con­cluded that olive oil pro­duc­tion with­out adding water results in higher-qual­ity Arbequina extra vir­gin olive oil with higher polyphe­nol counts.

The qual­ity and the sta­bil­ity of the Arbequina oils can be favored if extracted with­out adding water dur­ing the olives indus­trial milling,” they wrote. Doing this also means greater resilience to pro­longed stor­age and han­dling.

Water addi­tion has been used for gen­er­a­tions by many millers as it was often con­sid­ered an effi­cient method to get more oil out of the paste. However, this belief has been chal­lenged over the years.

For exam­ple, a study con­ducted nearly a decade ago by sci­en­tists at the University of Extremadura in Spain showed that adding water to the process caused a decrease in oil yield and oil extractabil­ity for both of the cul­ti­vars that had been tested.

Such stud­ies sug­gest the need for millers who still add water to exam­ine the ben­e­fits of water-less extrac­tion, which might also result in reduced energy con­sump­tion, less liq­uid residue and a higher qual­ity olive oil.


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