Application of Pulsed Electric Fields to Pilot and Industrial Scale Virgin Olive Oil Extraction: Impact on Organoleptic and Functional Quality

Abstract

The quality of virgin olive oil (VOO) is largely determined by the technology used in the industrial process of extracting the oil. Technological innovations within this field aim to strike a proper balance between oil yield and the optimal chemical composition of VOO. The application of pulsed electric fields (PEF) that cause the electroporation of the plant cell membranes favors a more efficient breakage of the olive fruit tissue, which in turn could facilitate the extraction of the oil and some of its key minor components. Pilot-scale and industrial extraction tests have been conducted to assess the effect of PEF technology on the oil extraction yield and on the organoleptic and functional quality of VOO. The best results were obtained by combining the PEF treatment (2 kV/cm) with short malaxation times and a low processing temperature. Under these conditions, PEF technology could decisively improve the oil yield by up to 25% under optimal conditions and enhance the incorporation of phenolic and volatile compounds into the oils. The PEF treatment neither affected the physicochemical parameters used to determine the commercial categories of olive oils, nor the tocopherol content. Similarly, the sensory evaluation of the PEF-extracted oils by means of a panel test did not detect the appearance of any defect or off-flavor. In addition, the intensity of positive attributes (fruity, bitter and pungent) was generally higher in PEF oils than in control oils.

Investigation on the Effects of a Pulsed Electric Field (PEF) Continuous System Implemented in an Industrial Olive Oil Plant

“…This seems to promote the release and transfer of polar molecules such as 3,4- DHPEA-EDA into the oil phase, which is known to slow down the negative oxidative phenomena in EVOO [ 34 ] and improve sensory and health properties [ 33 ]. The higher amount of oleuropein derivatives in EVOOs obtained after PEF treatment in olive pastes observed in this work is consistent with previous studies [ 19 , 23 , 29 , 38 ]. The ability of PEF technology to improve the solubility of oleuropein derivatives has already been described by Veneziani et al [ 29 ], who observed an increase in these phenolic compounds responsible for health-promoting benefits depending on the different olive varieties and their maturity index.…”

“…However, previous studies suggest that the variability of the content of this compound in EVOO is not influenced by processing conditions, while its actual content in oils depends on genetic and agronomic factors [ 39 ]. Our results are supported by a recent work [ 38 ] that investigated the differential effects of PEF treatment on secoiridoid derivatives as well as on tocopherol content. Our results differ from those of Abenoza et al [ 19 ] and Puértolas et al [ 20 ], who reported a higher increase in α-tocopherol content in EVOO from PEF treatment compared to EVOO from the traditional mechanical extraction process.…”

“…Both oils analyzed by the experts belonged to the marketable category “extra virgin”, which according to the current regulations [ 26 , 30 ] is characterized by a median of defects of zero or less (=0) and a median of fruitiness of more than zero (>0). These results indicate that the PEF technology does not impart an off-flavor to the oil, as has already been observed by several other authors [ 19 , 20 , 38 ] in oils of the Arbequina , Arroniz and Manzanilla varieties. As shown in Table 6 , both the control oils and the oils obtained by treating the olive pastes with PEF had a higher “bitter” aftertaste than the control oils, which is related to the increase in phenolic concentration in the oils obtained with PEF technology.…”

Olive Polyphenol Oxidase Gene Family

“…However, the application of this claim is restricted to those oils that contain at least 250 ppm of hydroxytyrosol and its derivatives [ 5 ]. This EFSA health claim has promoted the development of different lines of research to obtain oils enriched in HTy derivatives, such as a better understanding of the metabolism of phenolic compounds in the olive, through the identification of key enzymes/genes, the development of new extraction technologies that favor the accumulation of phenols [ 6 ] or the search for molecular markers that could help olive breeders in the identification of new olive genotypes with improved phenolic profiles.…”

Influence of Malaxation Conditions on Phenolic Composition of Virgin Olive Oils: A Brief Review

“…Furthermore, several novel and emerging technologies have been developed and applied to satisfy the growing consumer demand for VOO with higher quality and healthrelated composition, such as microwaves [27,28], pulsed electric fields (PEF) [29][30][31][32][33][34][35], and ultrasound treatments [27,[36][37][38][39][40][41][42][43][44][45][46][47]. Moreover, these technologies have been studied for their capability to enhance VOO chemical-sensory quality, as well as its health-related composition.…”