No abstract

The quality of the olives oil can be altered during their processing. This paper studies the influence that the washing of olive oils has on their alkyl esters content and on other quality parameters. A Central Composite Rotatable Design (CCRD) with five center points has been used to modify the factors, rotational frequency of the motor of the vertical centrifuge (between 34 and 47 Hz) and percentage of added water (between 6 and 34%). Results show that the content in alkyl esters of olive oils increases by the flow from the decanter to the vertical centrifuge. The use of water in the vertical centrifuge decreases the content in ethyl and methyl esters 0.8 and 0.6 mg/kg, respectively, per percentage unit of added water. The acidity, peroxide index, K232, chlorophyll, and carotenoid contents are slightly altered by the oil flow from the decanter to vertical centrifuge, but not by operating factors. K270, total polyphenols and orthodiphenols change with the speed of the vertical centrifuge, but water does not affect them. For the normal operation frequency of the centrifuge (50 Hz), K270 is increased about 14%, while the total polyphenols and orthodiphenols decrease by 27 and 62%, respectively. Practical applications: Quality control of olive oils (virgin and extra virgin). Olive‐oil production process: differences in the content of EE and TP between the vertical centrifuge way out and the decanter way out.

SUMMARY:The main objective of this paper is to obtain extra virgin olive oils (EVOOs) which are balanced in volatile and phenolic compounds. An experimental design was performed and response surface methodology was applied. The factors for malaxation were: temperature 20-40 °C, time 30-90 min, and hole diameter of hammer-crusher 4.5-6.5 mm. The results show that high temperatures and small hole diameter must be used in order to obtain a higher content in phenolic compounds, while for volatile compounds a low temperature and large hole diameter must be used. The models predict that the best and more balanced EVOO are obtained with the hole diameter of greater size and a medium-low temperature. Thus, for a hammer-crusher hole diameter of 6.5 mm 337 and 356 mg/kg total HPLC phenols were obtained for malaxation temperature of 20 and 25 °C, respectively and, likewise, 12.7 and 11.5 mg/kg total LOX volatiles. KEYWORDS: Balanced olive oils; Oil mill; Phenolic compounds; Response Surface Methodology; Volatile compounds RESUMEN:Modelado de compuestos volátiles y fenólicos y optimización de las condiciones de operación para obtener aceites de oliva virgen extra equilibrados. El principal objetivo es obtener aceites de oliva vírgenes extra (AOVEs) equilibrados en compuestos volátiles y fenólicos. Se ha realizado un diseño experimental y aplicado metodología de superficie de respuesta. El rango de los factores de batido fue, temperatura 20-40 ºC y tiempo 30-90 min, y diámetro de orificio del molino de martillos 4,5-6,5 mm. Los resultados muestran que a altas temperaturas y pequeño diámetro de orificio se obtienen elevados contenidos en compuestos fenólicos, mientras que para volátiles se debe usar temperatura baja y orificio de gran diámetro. Los modelos predicen que el mejor y más equilibrado EVOO se obtiene con el orificio de mayor tamaño y temperatura media-baja. Así, para diá-metro de orificio de 6,5 mm se obtienen 337 y 356 mg/kg de fenoles totales HPLC, para temperaturas de batido de 20 y 25 °C respectivamente y, asimismo, 12,7 y 11,5 mg/kg de volátiles totales LOX.

No abstract