Molecular and metabolic effects of extra-virgin olive oil on the cardiovascular gene signature in rodents.

BACKGROUND AND AIMS: Overweight and obesity are major risk factors for degenerative diseases, including cardiometabolic disorders and cancer. Research on fat and fatty acids' type is attracting less attention than that on carbohydrates. High adherence to a Mediterranean diet is associated with a better prognosis. One characteristic of the Mediterranean diet is extra-virgin olive oil (EVOO) as the foremost source of dietary fat. EVOO is different from other vegetable oils because it contains peculiar "minor" components, mainly phenolic in nature. Even though olive oil is highly caloric, unrestricted use of olive oil in the PREDIMED trial did not result in weight gain. We sought to study the effects of EVOO in an appropriate mouse model of increased body weight. Furthermore, we explored the biochemical and metabolomic responses to EVOO consumption. METHODS AND RESULTS: C57BL/6N male mice were weight-matched and fed ad libitum with the following diets, for 16 weeks: 1) saturated fatty acid diet (SFA) or 2) extra-virgin olive oil diet (EVOO), a custom-prepared diet, isocaloric compared to SFA, in which 82% of fat was replaced by high (poly)phenol EVOO. We evaluated glucose homeostasis, serum biochemistry and plasma metabolomics, in addition to cardiac and hepatic gene profile, and mitochondrial respiration rate. CONCLUSION: Replacing saturated fatty acids (e.g. lard) with EVOO translates into moderate yet beneficial cardiometabolic and hepatic effects. Future research will further clarify the mechanisms of action of EVOO (poly)phenols and their role in a balanced diet.

Bioactive Compounds and Stability of a Typical Italian Bakery Products "Taralli" Enriched with Fermented Olive Paste.

Olive paste (OP) is a novel by-product of olive mill industry composed of water, olive pulp, and skin. Due to its richness in bioactive compounds, OP exploitation for human consumption has recently been proposed. Starter driven fermented OP is characterized by a well-balanced lipid profile, rich in mono and polyunsaturated fatty acids, and a very good oxidative stability due to the high concentration of fat-soluble antioxidants. These characteristics make OP particularly suitable as a functional ingredient for food/feed industry, as well as for the formulation of nutraceutical products. New types of taralli were produced by adding 20% of fermented OP from black olives (cv Cellina di Nardò and Leccino) to the dough. The levels of bioactive compounds (polyphenols, triterpenic acids, tocochromanols, and carotenoids), as well as the fatty acid profile, were monitored during 180 days of storage and compared with control taralli produced with the same flour without OP supplementation. Taralli enriched with fermented OP showed significantly higher levels of bioactive compounds than conventional ones. Furthermore, enriched taralli maintained a low amount of saturated fatty acids and high levels of polyphenols, triterpenic acids, tocochromanols, and carotenoids, compared to the initial value, up to about 90 days in the usual conditions of retailer shelves.

In Vitro Anti-Inflammatory Effects of Phenolic Compounds from Moraiolo Virgin Olive Oil (MVOO) in Brain Cells via Regulating the TLR4/NLRP3 Axis.

Neuroinflammation is a feature of many classic neurodegenerative diseases. In the healthy brain, microglia cells are distributed throughout the brain and are constantly surveilling the central nervous system (CNS). In response to CNS injury, microglia quickly react by secreting a wide array of apoptotic molecules. Virgin olive oil (VOO) is universally recognized as a symbol of the Mediterranean diet. In the current study, using lipopolysaccharide (LPS)-stimulated BV2 microglia, the anti-inflammatory effects of VOO phenolic extracts from Moraiolo cultivar (MVOO-PE) were investigated. The results showed that low concentration of MVOO-PE prevented microglia cell death and attenuated the LPS-induced activation of toll-like receptor 4 (TLR4)/NOD-like receptor pyrin domain-containing-3 (NLRP3) signaling cascade. The levels of TLR4 and NF-kB were diminished, as well as NLRP3 inflammasome and interleukin-1ß (IL-1ß) production. Cyclooxygenase-2 (COX-2) isoenzyme and ionized calcium binding adaptor molecule 1 (Iba-1) inflammatory mediator were also reduced. By modulating the TLR4/NLRP3 axis, MVOO-PE pretreatment was able to significantly down-regulate the mRNA expression of inflammatory mediators and suppress the cytokine secretion. Finally, we showed protective effect of MVOO-PE in a transwell neuron-microglia co-culture system. In conclusion, these results suggest that MVOO-PE could exerts anti-inflammatory activity on brain cells and become a promising candidate for preventing several neuroinflammatory diseases.

Toward a Harmonized and Standardized Protocol for the Determination of Total Hydroxytyrosol and Tyrosol Content in Virgin Olive Oil (VOO). The Pros of a Fit for the Purpose Ultra High Performance Liquid Chromatography (UHPLC) Procedure.

Τoward a harmonized and standardized procedure for the determination of total hydroxytyrosol and tyrosol content in virgin olive oil (VOO), the pros of a recently published in house validated ultra high performance liquid chromatography (UHPLC) protocol are discussed comparatively with those of other procedures that determine directly or indirectly the compounds hosted under the health claim on "olive oil polyphenols" (EC regulation 432/2012). Authentic VOOs were analyzed with five different liquid chromatographic separation protocols and 1H-NMR one in five different laboratories with expertise in VOO phenol analysis within three months. Data comparison indicated differences in absolute values. Method comparison using appropriate tools (Passing-Bablok regression and Bland Altman analyses) for all protocols vs. the UHPLC one indicated slight or statistically significant differences. The results were also discussed in terms of cost effectiveness, detection means, standard requirements and ways to calculate the total hydroxytyrosol and tyrosol content. Findings point out that the in-house validated fit for the purpose UHPLC protocol presents certain pros that should be exploited by the interested parties. These are the simplicity of sample preparation, fast elution time that increase the number of samples analyzed per day and integration of well-resolved peaks with the aid of only two commercially available external standards. Importance of correction factors in the calculations is stressed.

Oleuropein aglycone and polyphenols from olive mill waste water ameliorate cognitive deficits and neuropathology.

AIM: In TgCRND8 (Tg) mice we checked the dose-response effect of diet supplementation with oleuropein aglycone (OLE) at 12.5 or 0.5 mg kg-1 of diet. We also studied the effects of dietary intake of the mix of polyphenols present in olive mill waste water administered at a total dose as high as the highest dose of OLE (50 mg kg-1 of diet) previously investigated. METHODS: Four month-old Tg mice were equally divided into four groups and treated for 8 weeks with a modified low fat (5.0%) AIN-76 A diet (10 g day-1  per mouse) as such, supplemented with OLE (12.5 or 0.5 mg kg-1 of diet) or with a mix of polyphenols (50 mg kg-1 of diet) found in olive mill waste water. Behavioural performance was evaluated by the step down inhibitory avoidance and object recognition tests. Neuropathology was analyzed by immunohistochemistry. RESULTS: OLE supplementation at 12.5 mg kg-1 of diet and the mix of polyphenols was found to improve significantly cognitive functions of Tg mice (P < 0.0001). Aß42 and pE-3Aß plaque area and number were significantly reduced in the cortex by OLE and in the cortex and hippocampus by the mix of polyphenols (P < 0.01, P < 0.001 and P < 0.0001). Similar autophagy induction was found in the brain cortex of differently treated mice. CONCLUSION: Our results extend previous data showing that the effects of OLE on behavioural performance and neuropathology are dose-dependent and not closely related to OLE by itself. In fact, diet supplementation with the same dose of a mix of polyphenols found in olive mill waste water resulted in comparable neuroprotection.

Irrigation and fruit canopy position modify oil quality of olive trees (cv. Frantoio).

BACKGROUND: Fruit development and oil quality in Olea europaea L. are strongly influenced by both light and water availability. In the present study, the simultaneous effects of light environment and irrigation on fruit characteristics and oil quality were studied in a high-density orchard over two consecutive years. Olive fruits were harvested from three canopy positions (intercepting approximately 64%, 42% and 30% of above canopy radiation) of fully-productive trees subjected to full, deficit or complementary irrigation. RESULTS: Fruits receiving 61-67% of above canopy radiation showed the highest fruit weight, mesocarp oil content and maturation index, whereas those intercepting only 27-33% showed the lowest values. Palmitoleic and linoleic acids increased in oils obtained from fruits exposed to high light levels, whereas oleic acid and the oleic-linoleic acid ratio decreased. Neither canopy position, nor irrigation affected K232 , K270 , ΔK and the concentration of lignan in virgin olive oils (VOOs). Total phenols, 3,4-DHPEA-EDA [2-(3,4-hydroxyphenyl)ethyl (3S,4E)-4-formyl-3-(2-oxoethyl)hex-4-enoate] and p-HPEA-EDA (decarboxymethyl ligstroside-aglycone) increased in VOOs produced from fruits harvested from the top of the canopy, whereas full irrigation decreased total phenols and 3,4-DHPEA-EDA concentrations with respect to the complementary irrigation treatment. CONCLUSION: Light and water availability are crucial not only for tree productivity, but also they clearly affect olive oil quality. © 2017 Society of Chemical Industry.

Content of fatty acids and phenolics in Coratina olive oil from Tunisia: influence of irrigation and ripening.

The quality indices and chemical composition of Coratina olive oil produced in the northern region of Tunisia were evaluated, to determine the effect of three different irrigation regimes of the trees on the olive oils. The olives were sampled at two different stages of maturity, the oils were extracted, and standard methods were used to analyze the composition and quality of the oils. The fatty-acid contents and quality parameters were only slightly affected by the irrigation regime. The contents of palmitic, oleic, and linoleic acids were above 12, 72, and 8%, respectively, for the second harvest, regardless of the irrigation level of the olive trees. Parameters such as the α-tocopherol content and the phenolic profile were found to be significantly affected by the harvesting time; however, inconsistent changes were observed for the irrigation regimes, especially for the oil of the second harvest. It was shown that the irrigation conditions of the olive trees as well as the harvesting time of the fruits gave rise to a diverse range of olive oils in Tunisia.

Preventive activity of olive oil phenolic compounds on alkene epoxides induced oxidative DNA damage on human peripheral blood mononuclear cells.

The aim of this study was to investigate the ability of epoxides of styrene (styrene-7,8-oxide; SO) and 1,3-butadiene (3,4-epoxy-1-butene; 1,2:3,4:-diepoxybutane) to cause oxidative stress and oxidative DNA damage on human peripheral blood mononuclear cells (PBMCs) and whether a complex mixture of olive oil phenols (OOPE) could prevent these effects. The DNA damage was measured by the single-cell gel electrophoresis (SCGE; comet assay). We found that the DNA damage induced by alkene epoxides could be prevented by N-acetyl-cysteine (10 mM) and catalase (100 U/ml). Alkene epoxides caused a significant (P < 0.05) increase of both peroxide concentration in extra- and intracellular environment and formamidopyrimidine DNA glycosylase (FPG)- and Endonuclease III (ENDO III)-sensitive sites in PBMCs, demonstrating the presence of oxidized bases. OOPE (1 µg of total phenols/ml) was able to prevent the alkene epoxide induced DNA damage both after 2 and 24 h of incubation. In addition, OOPE completely inhibited the SO-induced intracellular peroxide accumulation in PBMCs and prevented the oxidative DNA damage induced by SO, as evidenced by the disappearance of both FPG- and ENDO III-sensitive sites. This is the first study demonstrating the ability of OOPE to prevent the DNA damage induced by alkene epoxides providing additional information about the chemopreventive properties of olive oil.

Effect of stoned olive pomace on rumen microbial communities and polyunsaturated fatty acid biohydrogenation: an in vitro study.

BACKGROUND: Stoned olive pomace (SOP), which represents approximately 50% of the conversion process of olives to olive oil, is largely not utilised and creates costs for its disposal and has negative environmental impacts. In vitro trial experiments were employed to study the effect of feeds integrated with this bio-waste, which is rich in polyphenols, on rumen biohydrogenation, using sheep rumen liquor as inoculum. RESULTS: Fatty acid (FA) analysis and a polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) approach aimed at characterising the microbial community indicated that including SOP in feeds at the level of 50 g/kg and 90 g/kg induced changes in the FA profile and microbial populations. The simultaneous decrease of Butyrivibrio proteoclasticus and accumulation of vaccenic acid was observed. A depression in the populations of Neisseria weaveri, Ruminobacter amylophilus and other unclassified bacteria related to members of the Lachnospiraceae and Pasteurellaceae families was detected, suggesting that these microbial groups may be involved in rumen biohydrogenation. CONCLUSIONS: Supplementation of feeds with SOP alters the rumen bacterial community, including bacteria responsible for the hydrogenation of vaccenic acid to stearic acid, thereby modifying the FA profile of the rumen liquor. Hence, a use of SOP aimed to produce meat or dairy products enriched in functional lipids can be hypothesised.

The Anti-Neuroinflammatory Effect of Extra-Virgin Olive Oil in the Triple Transgenic Mouse Model of Alzheimer's Disease.

Background: Chronic intake of extra virgin olive oil is beneficial for brain health and protects from age-related cognitive decline and dementia, whose most common clinical manifestation is Alzheimer's disease. Besides the classical pathologic deposits of amyloid beta peptides and phosphorylated tau proteins, another frequent feature of the Alzheimer's brain is neuroinflammation. Objective: In the current study, we assessed the effect that extra virgin olive oil has on neuroinflammation when administered to a mouse model of the disease. Methods: Triple transgenic mice were randomized to receive a diet enriched with extra virgin olive oil or regular diet for 8 weeks. At the end of this treatment period the expression level of several inflammatory biomarkers was assessed in the central nervous system. Results: Among the 79 biomarkers measured, compared with the control group, mice receiving the extra virgin olive oil had a significant reduction in MIP-2, IL-17E, IL-23, and IL-12p70, but an increase in IL-5. To validate these results, specific ELISA kits were used for each of them. Confirmatory results were obtained for MIP-2, IL-17E, IL-23, and IL-12-p70. No significant differences between the two groups were observed for IL-5. Conclusions: Our results demonstrate that chronic administration of extra virgin olive oil has a potent anti-neuroinflammatory action in a model of Alzheimer's disease. They provide additional pre-clinical support and novel mechanistic insights for the beneficial effect that this dietary intervention has on brain health and dementia.

Evaluation of the Effect of an Olive Phenolic Extract on the Secondary Shelf Life of a Fresh Pesto.

Recent advances in the olive oil sector aim to develop sustainable strategies for the valorisation of mechanical extraction co-products as a rich source of bioactive compounds with antioxidant and antimicrobial activities. In this work, we studied the effectiveness of a phenolic extract (PE) from olive vegetation water (OVW) as a new antioxidant of natural origin for improving the quality and extending the secondary shelf life (SSL) of a fresh basil pesto sold as a served loose product at the deli counter, simulating the storage conditions after packaging, opening, and serving. For that, the PE was mixed with the oily phase of fresh pesto in two different concentrations and compared to a control pesto (CTRL) made with the addition of common additives (ascorbic acid (E300) and sorbic acid (E200)). The physicochemical parameters, phenolic and volatile composition, sensory profiles, and antioxidant capacity of the experimental pesto samples were evaluated after opening. The results proved that the enrichment with the PE improved the stability of the pesto and, hence, its overall quality. The PE provided higher protection than the CTRL against primary and secondary oxidation at both concentrations tested and delayed the accumulation of the volatile compounds responsible for the 'rancid' off-flavour up to 7 days after first opening, while also preserving higher levels of the pesto phytonutrients (such as the rosmarinic, caffeic, and chicoric acids and α-tocopherol). These results show that the generation of food waste in households, catering chains, retail, and/or restaurants can be reduced, improving the sustainability of the food industry and the competitiveness of the olive oil sector.

Feeding pigs with hazelnut skin and addition of a concentrated phenolic extract from olive-milling wastewaters during pork processing: Effects on salami quality traits and acceptance by the consumers.

Two groups of ten barrows received a conventional- (CTRL) or an experimental- (HZL) finishing diet containing 11% of hazelnut skin. From each barrow, two types of salami (namely, NITR, and PHEN) were obtained. NITR salami was added with E250 and E252. The latter were replaced by a phenolic concentrated extract from olive-milling wastewaters in PHEN salami. Salami fatty acids (FA), antioxidant capacity, lipid and color stability during refrigerated storage were assessed. A consumer test was also performed. Feeding strategy minimally affected the investigated parameters. PHEN salami had lower TBARS than NITR salami (P-value <0.001) during refrigerated storage despite comparable antioxidant capacity and similar PUFA content. Moreover, within CTRL group, lipid oxidation was lower in PHEN than NITR salami (P-value = 0.040). At the blind taste, dietary treatment did not affect salami sensorial properties nor consumer acceptance, whereas NITR salami showed better color (P-value = 0.036). Interestingly, HZL and PHEN salami showed improved sensorial properties and consumer acceptance after that consumers received information on salami origin.

Exploring the relevance of the type of horizontal separator to optimize the extraction efficacy for the Arbequina variety.

The productivity of virgin olive oil depends not only on agronomic factors but also on the technological factors of the extraction process. The 'Arbequina' variety has extractability problems, which is a challenge for master millers anywhere. This work aims to evaluate the behavior of different decanters and seeks to modulate the effect of some processing parameters and their interactions with oil extraction efficiency in the case of 'Arbequina.' Fruit characteristics, processing parameters, and extractability were collected over 10 years from 38 decanters that belong to five different brands. The results have shown that fruit moisture is the most relevant factor for oil extractability, especially over 52%. Furthermore, extractability is positively correlated with malaxing temperature, addition of water, and total fat content in the fruit. However, the results show that before applying a regulation, the type of decanter must be considered. The model used in this study has allowed us to optimize the regulations for each type of decanter to reduce oil losses within the pomace, achieving an extraction efficiency within the range of 78%-91.5%. In fact, the best extraction efficiency results (91.5%) were obtained by processing at temperatures >26°C and water injection of 5%.

Effect of Controlled Oxygen Supply during Crushing on Volatile and Phenol Compounds and Sensory Characteristics in Coratina and Ogliarola Virgin Olive Oils.

In virgin olive oil industries, the technological choices of the production plant affect the biochemical activities that take place in the olives being processed throughout the entire process, thereby affecting the quality of the final product. The lipoxygenase pool enzymes that operated their activity during the first phases of the process need the best conditions to work, especially concerning temperature and oxygen availability. In this study, a system was equipped to supply oxygen in the crusher at a controllable concentration in an industrial olive oil mill at pilot plant scale, and four oxygen concentrations and two cultivars, Coratina and Ogliarola, were tested. The best concentration for oxygen supply was 0.2 L/min at the working capacity of 0.64 Ton/h. Further, using this addition of oxygen, it was possible to increase the compound's concentration, which is responsible for the green, fruity aroma. The effect on volatile compounds was also confirmed by the sensory analyses. However, at the same time, it was possible to maintain the concentration of phenols in a good quality olive oil while also preserving all the antioxidant properties of the product due to the presence of phenols. This study corroborates the importance of controlling oxygen supply in the first step of the process for process management and quality improvement in virgin olive oil production.

Characterization of Olive Fruit Damage Induced by Invasive Halyomorpha halys.

The brown marmorated stink bug, Halyomorpha halys (Stål), is an invasive species causing economic crop losses. This species was recently detected attacking olive fruits. The aim of this study was to characterize feeding damage. Olive samples were initially collected from a field where H. halys was reported to cause damage to olive fruits. Hence, we conducted a field trial on the Moraiolo variety using sleeve cages to test the effect of H. halys feeding pressure on olive fruit drop and evaluated the effect of feeding on fruit quality. We tested two densities of H. halys (two or eight adults/cage) at two different stages of olive development, pre- and post-pit hardening. High pressure of H. halys before pit hardening caused a significant fruit drop compared to the control. In addition, chemical analysis of damaged and infested fruits revealed higher levels of total phenols compared to healthy fruits. These findings indicate that feeding by H. halys induced a stress response in the plants that could translate in quality variations in the olive drupes.

Frozen Ready-to-(h)eat Meals: Evolution of Their Quality during a Real-Time Short Shelf Life.

The purpose of this experimentation was to study the evolution of the quality of two types of blast-frozen ready-to-(h)eat meals, tortellini and a vegetable soup, during a short shelf life of 70 days. The analyses, performed in order to identify any variations resulting either from the freezing process or from the subsequent storage, carried out at the temperatures of -30 °C and -18 °C, respectively, examined the consistency of the tortellini and the soup, the acidity and the peroxide value of the oil extracted from them, the phenols and carotenoids present in the soup, the volatile compounds in the tortellini and the soup, and a sensory analysis of both products. The results showed that, during the 70 days of shelf life, there was no variation in the texture of the tortellini, but there were changes in the consistency of the soup, which decreased as the days of storage went on. Furthermore, statistically significant increases (p < 0.05) in the acidity and in the peroxide value of the oil of the soup were observed during the storage period; however, no statistically significant difference (p > 0.05) in the peroxide value of the oil of the tortellini was found. Moreover, no quantitative changes were observed in the phenolic compounds and carotenoids in the soup or in the volatile substances of either product. Finally, the sensory analysis confirmed, together with the chemical data, that the blast-freezing process adopted was suitable to maintain the good quality of these fresh meals, even if some technical modifications (in particular, lower freezing temperatures) should be adopted to improve the final quality of the products.

Potential of the Oxidized Form of the Oleuropein Aglycon to Monitor the Oil Quality Evolution of Commercial Extra-Virgin Olive Oils.

The quality of commercially available extra-virgin olive oils (VOOs) of different chemical compositions was evaluated as a function of storage (12 months), simulating market storage conditions, to find reliable and early markers of the virgin olive oil (VOOs) quality status in the market. By applying a D-optimal design using the Most Descriptive Compound (MDC) algorithm, 20 virgin olive oils were selected. The initial concentrations of oleic acid, hydrophilic phenols, and α-tocopherol in the 20 VOOs ranged from 58.2 to 80.5%, 186.7 to 1003.2 mg/kg, and 170.7-300.6 mg/kg, respectively. K270, ∆K, (E, E)-2.4-decadienal and (E)-2-decenal, and the oxidative form of the oleuropein aglycon (3,4-DHPEA-EA-OX) reflected the VOO quality status well, with 3,4-DHPEA-EA-OX being the most relevant and quick index for simple monitoring of the "extra-virgin" commercial shelf-life category. Its HPLC-DAD evaluation is easy because of the different wavelength absorbances of the oxidized and non-oxidized form (3,4-DHPEA-EA), respectively, at 347 and 278 nm.

Method for the analysis of volatile compounds in virgin olive oil by SPME-GC-MS or SPME-GC-FID.

During the course of the EU H2020 OLEUM project, a harmonized method was developed to quantify volatile markers of the aroma of virgin olive oil with the aim to support the work of sensory panel test to assess the quality grade. A peer validation of this method has been carried out, with good results in terms of analytical quality parameters. The method allows the quantification of volatile compounds by SPME-GC with two possible detectors, flame ionization detector and mass spectrometry, depending on the technical facilities of the labs applying this method. The method was optimized for the quantification of 18 volatile compounds that were selected as being markers responsible for positive attributes (e.g. fruity) and sensory defects (e.g. rancid and winey-vinegary). The quantification is carried out with calibration curves corrected by the internal standards. Additionally, a protocol is provided to prepare the calibration samples. This procedure enhances reproducibility between labs since one of the main sources of errors is the application of different procedures in calibration.

Olive phenolic compounds: metabolic and transcriptional profiling during fruit development.

BACKGROUND: Olive (Olea europaea L.) fruits contain numerous secondary metabolites, primarily phenolics, terpenes and sterols, some of which are particularly interesting for their nutraceutical properties. This study will attempt to provide further insight into the profile of olive phenolic compounds during fruit development and to identify the major genetic determinants of phenolic metabolism. RESULTS: The concentration of the major phenolic compounds, such as oleuropein, demethyloleuropein, 3-4 DHPEA-EDA, ligstroside, tyrosol, hydroxytyrosol, verbascoside and lignans, were measured in the developing fruits of 12 olive cultivars. The content of these compounds varied significantly among the cultivars and decreased during fruit development and maturation, with some compounds showing specificity for certain cultivars. Thirty-five olive transcripts homologous to genes involved in the pathways of the main secondary metabolites were identified from the massive sequencing data of the olive fruit transcriptome or from cDNA-AFLP analysis. Their mRNA levels were determined using RT-qPCR analysis on fruits of high- and low-phenolic varieties (Coratina and Dolce d'Andria, respectively) during three different fruit developmental stages. A strong correlation was observed between phenolic compound concentrations and transcripts putatively involved in their biosynthesis, suggesting a transcriptional regulation of the corresponding pathways. OeDXS, OeGES, OeGE10H and OeADH, encoding putative 1-deoxy-D-xylulose-5-P synthase, geraniol synthase, geraniol 10-hydroxylase and arogenate dehydrogenase, respectively, were almost exclusively present at 45 days after flowering (DAF), suggesting that these compounds might play a key role in regulating secoiridoid accumulation during fruit development. CONCLUSIONS: Metabolic and transcriptional profiling led to the identification of some major players putatively involved in biosynthesis of secondary compounds in the olive tree. Our data represent the first step towards the functional characterisation of important genes for the determination of olive fruit quality.

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

The aim of this study was to investigate how the treatment of olive paste of the Picholine variety with pulsed electric fields (PEF) under real operating conditions in a large-scale olive oil extraction plant affects the extractability, chemical composition and sensory profile of the oils. The application of pulsed electric fields (PEF) as a non-thermal food processing technology is interesting for many food extraction processes. The results of this study show that pulsed electric fields can be used as a pretreatment before oil separation to increase the extractability of the process and improve the content of functional components. The application of pulsed electric field (PEF) treatment (2.4 kV/cm, 4 kJ/kg, 6 µs pulse width) to olive paste through a continuous system significantly increased the extractability and total concentration of phenols (especially oleuropein derivatives) compared to the control. In addition, the volatile compounds, α-tocopherol, the fatty acid profile and the main legal quality parameters of extra virgin olive oil (EVOO), including free acidity, peroxide values, extinction indices and sensory analysis, were evaluated. The pulsed electric fields (PEF) treatment did not modify these EVOO quality parameters, neither the α-tocopherol content nor the volatile profile. The sensory properties of EVOO were not affected as well as the PEF treatment showed a similar intensity of fruity and pungent attributes without any off-flavor according to the European Union legal standards. An increase in the bitter taste attribute was observed in the PEF oils. Consequently, this study demonstrates that pulsed electric fields (PEF) processing could be implemented in olive oil processing as pretreatment for improving the efficiency of the process.