A novel crushing process which involves increasing the level of oxygen during the virgin olive oil (VOO) extraction has been applied to develop new knowledge on the biosynthesis of the compounds responsible for sensory, nutritional, and technological quality of VOO. The singular composition of VOO is the result of a series of physical, chemical, and biochemical processes that occur during its extraction procedure. The extraction conditions, temperature, time, addition of water, and oxygen availability, can modulate the final composition of VOO. The last parameter, oxygen, is a known co‐factor for the many endogenous enzyme activities present in the olive fruit, mainly oxide‐reductases. The present study focuses on the influence of oxygen during the crushing of olive fruits on enzyme activities and the process yield. Three different cultivars, namely “Picual,” “Arbequina,” and “Blanqueta”, were selected for the study. The increase of oxygen concentration during crushing produces a significant change in the volatile composition and sensory profile; however, no significant differences were shown on the content of fatty acid composition, total phenols, pigments, tocopherols, and qualitative parameters. This could be a useful analysis tool while designing new prototypes of mills or while working with breeding selection programs. Practical applications: The application of oxygen during olive fruit crushing in the oil extraction process has been studied. The information provided by this study enables to increase the knowledge on metabolism pathway in olive fruit while working with breeding selection programs. The present study can be useful to clarify the optimum time, crushing, or malaxation to apply atmospheric control to the VOO extraction. Moreover, the results obtained in this work suggest new research opportunities in order to design new prototypes of mills that allow the modification of the sensory characteristics VOO. The increase of oxygen concentration during crushing produces a significant change in the volatile composition and sensory profile; however, no significant differences were shown on the content of fatty acid composition, total phenols, pigments, tocopherols, and qualitative parameters. Oxygen availability can modulate the final composition of virgin olive oil.

No abstract

RESUMEN Empleo de ultrasonidos de potencia en el proceso de elaboración del aceite de oliva virgen. Resultados a nivel de planta de laboratorioMediante aplicación indirecta con baño ultrasónico de 25 kHz, han sido analizados los efectos de la aplicación de ultrasonidos de potencia sobre la etapa de termobatido del proceso de elaboración del aceite de oliva virgen a nivel de planta de laboratorio.Un rápido calentamiento de la pasta de aceituna molida desde la temperatura ambiente a la temperatura óptima de trabajo (30°C) y una mejora en la extractabilidad del proceso han sido los dos hechos observados más importantes bajo el punto de vista del rendimiento industrial.Las características de los aceites, en cuanto a paráme-tros de: índice de acidez, índice de peróxidos, K270, K232 y amargor (K225), no se han visto afectadas, en las condiciones en que se han llevado a cabo los ensayos, por el tratamiento de la masa con ultrasonidos de potencia. PALABRAS-CLAVE: Batido -Elaboración de aceite de oliva virgen -Extractabilidad -Ultrasonidos de potencia. SUMMARY Use of high power ultrasounds in virgin olive oil extraction process. Results at laboratory scaleThe effects of high-power ultrasound on olive paste, in a laboratory thermomixing operation for virgin olive oil extraction, have been studied. Indirect sonication in a thermomixer with an ultrasound cleaning bath, at 25 kHz, has been applied.A quick heating of olive paste, to optimal temperature conditions and an extractability improvement of the extraction process were found with the sonication of olive paste.The effects of high-power ultrasound on some components of the oil obtained were studied. Free acidity, peroxide value, K270, K232, and bitterness (K225) were determined immediately and 4 months later. KEY-WORDS: Extractability INTRODUCCIÓNEn los últimos años, el aceite de oliva virgen ha visto incrementado su producción y consumo a consecuencia de su demanda como producto natural, sano y nutritivo, siendo éste, prácticamente, el único aceite de gran producción que por su particular forma de obtención, puede ser consumido directamente sin necesidad obligada de pasar por refinación.El aceite de oliva virgen es obtenido empleando exclusivamente procedimientos físicos, en una serie de procesos concatenados empezando por la molienda del fruto, para romper la estructura de las células donde se aloja el aceite; seguido de un termobatido a un tiempo y temperatura controlada, a fin de obtener una fase oleosa continua y diferenciada lo mas posible del resto de los componentes de la masa; una separación de fases mediante aplicación de presión o fuerza centrífuga, en la que se consigue separar el aceite del agua de vegetación y de los sólidos; y una decantación final, con o sin centrifugación previa, para separar el resto de partículas en suspensión en el aceite. En definitiva, el proceso de obtención del aceite de oliva virgen es todo un conjunto de operaciones básicas de transferencia de calor, transporte de masas, filtraciones y sedimentaciones que tiene como objetivo l...

In commercial terms, Extra Virgin Olive Oil (EVOO) is considered an exceptional food with excellent sensory and nutritional quality due to its taste, odor, and bioactive compounds; as such, it is of great health interest. This quality can be affected by the oxidative degradation, both chemical and enzymatic (the activity of oxidative, endogenous enzymes from the polyphenol oxidase and peroxidase olive fruit type), of essential components during the extraction and conservation of EVOO. In the bibliography, oxygen reduction during the malaxation process and oil storage has been studied in different ways. However, research concerning oxygen reduction in the crushing of the olive fruit or the malaxation of the paste, or both, in the “real extraction condition” is scarce. Oxygen reduction has been compared to control conditions (the concentration of atmospheric oxygen (21%)). Batches of 200 kg of the olive fruit, ‘Picual’ cultivar, were used and the following treatments were applied: Control (21% O2 Mill–21% O2 Mixer), “IC-NM”: Inerted crushing -Normal malaxation (6.25% O2 Mill-21% O2 Mixer), “NC-IM”: Normal crushing-Inerted malaxation (21% O2 Mill-4.39% O2 Mixer) and “IC-IM”: Inerted crushing -Inerted malaxation (5.5% O2 Mill-10.5% O2 Mixer). The parameters of commercial quality covered by regulation (free acidity, peroxide value and absorbency in ultra-violet (K232 and K270)) did not suffer any change concerning the control, and so the oils belong to the commercial category of “Extra Virgin Olive Oil”. The phenolic compounds of the olives involved in the distinctive bitter and pungent taste, health properties, and oxidative stability are increased with the downsizing amounts of oxygen in the IC-NM, NC-IM, and IC-IM treatments with an average of 4, 10, and 20%, respectively. In contrast, the total amount of volatile compounds decreases by 10–20% in all oxygen reduction treatments. The volatile compounds arising from the lipoxygenase pathway, which are responsible for the green and fruity notes of EVOO, also decreased in concentration with the treatments by 15–20%. The results show how oxygen reduction in the milling and malaxation stages of olive fruit can modulate the content of phenols, volatile compounds, carotenoids, and chlorophyll pigments in the EVOO to avoid the degradation of the compound with sensorial and nutritional interest.