Application of High Power Ultrasounds in the Virgin Olive Oil Extraction Previous to Olive Paste Malaxation
Mohamed Aymen Bejaoui1*, Araceli Sánchez-Ortiz*, Angélica Quintero*, Antonio Jiménez* and Gabriel Beltrán2*.
* IFAPA Centro “Venta del Llano”. Junta de Andalucía. P.O. Box 50, 23620 Mengíbar, Jaén, Spain.
 
Continuous application of high power ultrasounds (HPU) on olive paste previous to malaxation and its effect on process yield and the virgin olive oil (VOO) quality have been studied.
Olive oil elaboration pilot scale was composed of four units: a rollers mill, a rectangular pipeline for olive paste transport equipped with three 40 KHz frequency piezoelectric transducers powered by a 150 W ultrasonic generator, a thermo-malaxer and a paste centrifuge.  
Olive fruits from `Picual´ cultivar were collected at early véraison ripening stage, moisture and oil content were analyzed. VOO elaborated with HPU application was compared with reference without HPU application. HPU treatment applied was 100% of the power and olive paste flow of 20 kg/hour to achieve 30ºC of paste temperature. For the VOO samples were determined the quality index (free acidity value, peroxide value, K232, K270), bitterness, phenolic content (Total and biophenols), tocopherol content and pigments.  
The application of ultrasound induced a quick heating of the paste from 20ºC to 30ºC in 3 minutes whereas it took 20 to 30 minutes without HPU application. Sonication treatment improves about 1 % the industrial oil yield and gave higher extractability  46.83 % without HPU application to 52.57 % using HPU. 
VOO quality did not show changes in the quality parameters (free acidity value, peroxide value, K232, K270), and the fatty acid composition. Bitterness, phenolic content, tocopherol content and pigments were affected by HPU application. 
Oil obtained with HPU application showed a higher content of tocopherol, chlorophylls and carotenoids. Regarding bitterness and phenolic content (total phenols and biophenols), mainly for biophenols, decreased with HPU treatment.

1 email: mohamed.aymen.ext@juntadeandalucia.es
2 email: gabriel.beltran@juntadeandalucia.es