`Ultrasound Prevents Olive Oil from Going Solid in the Fridge

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Ultrasound Prevents Olive Oil from Going Solid in the Fridge

Jan. 16, 2013
By Julie Butler

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The harm­less but unsightly crys­tal­liza­tion that occurs when olive oil is stored in a fridge could be pre­vented by ultra­sound treat­ment, Span­ish sci­en­tists say.

They are seek­ing an inter­na­tional patent for their method, which includes apply­ing ultra­sonic pulses of 300 – 350W to olive oil in an opaque glass bot­tle, ide­ally for ten min­utes, then remov­ing any air in the bot­tle by sparg­ing’ with an inert gas such as argon.

The researchers, from the Uni­ver­si­tat de les Illes Balears (UIB), said they found extra vir­gin olive oil thus pre-treated could be stored for at least 16 months at 4 – 6°C (39.2 – 42.86°F), retain­ing its physico-chem­i­cal and sen­sory prop­er­ties, yet with no or very lit­tle crys­tal­liza­tion.

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Fast and afford­able

The tech­nol­ogy is said to be quick and cost effec­tive, using afford­able and com­mer­cially avail­able equip­ment, and is offered for license to com­pa­nies engaged in pro­duc­tion and pack­ag­ing of olive oil.

In tests using empel­tre vari­ety extra vir­gin olive oil from the island of Mal­lorca with an ini­tial grade of acid­ity of 0.7 the sci­en­tists found keep­ing it at 0 – 8°C (32 – 46.4°F) was opti­mal for its preser­va­tion. The results show that the stor­age period of this oil in par­tic­u­lar, one that due to its acid­ity is very close to los­ing the extra vir­gin cat­e­gory, increases from 6 months to 12 months.”

How­ever with­out treat­ment, stor­age at low tem­per­a­tures causes unat­trac­tive cloudy blobs in the oil due to crys­tal­liza­tion of its fatty acids, mainly oleic acid.

Ultra­sound does­n’t harm” oil qual­ity

Exper­i­ments found the ultra­sound treat­ment did not affect key phys­i­cal and chem­i­cal indi­ca­tors of extra vir­gin olive oil qual­ity and avoided or sig­nif­i­cantly reduced the prob­lem of crys­tal­liza­tion.

Pre­treat­ment with ultra­sonic pulses and stor­age of oil under opti­mal con­di­tions may be a good method of preser­va­tion, because apart from main­tain­ing the oil’s physico-chem­i­cal and organolep­tic qual­i­ties, the oil can be kept in a liq­uid state for longer at fridge tem­per­a­ture because a com­mon prob­lem with oils kept at low tem­per­a­ture — crys­tal­liza­tion of the fatty mate­r­ial — is avoided,” the patent appli­ca­tion says.

Accord­ing to a a UIB web­site, the method can be used for the preser­va­tion of extra vir­gin olive oils of all vari­eties and espe­cially those with a high degree of acid­ity. It has not been tested with plas­tic con­tain­ers due to the ease of trans­fer of com­po­nents of the con­tainer to its con­tents dur­ing the process.”



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