Search Results (53)

Virgin olive oil (VOO) quality is strongly influenced by olive cultivar and fruit maturity stage, yet their combined effects remain insufficiently characterized in many traditional olive-growing regions. This study evaluated the physicochemical parameters, phenolic compounds content, antioxidant activity, fatty acid profile, volatile compounds, and sensory attributes of VOOs obtained from five autochthonous cultivars of Extremadura (Spain)—‘Corniche’, ‘Manzanilla Cacereña’, ‘Morisca’, ‘Pico Limón’, and ‘Verdial de Badajoz’—harvested at three ripening stages (Green, Verging-on-ripe, and Ripe). Early harvest oils exhibited significantly higher total phenolic content (up to 478 mg/kg expressed by caffeic acid equivalent, CAE), oxidative stability (up to 188 h), intense green-fruity notes dominated by (E)-2-hexenal and (Z)-3-hexenal, and stronger bitterness and pungency. As ripening progressed, phenolic compounds and LOX-derived C6 volatiles markedly decreased, while oil yield, linoleic acid, saturated aldehydes, and oxidation markers increased in most cultivars. Cultivar-specific responses were evident: ‘Corniche’ and ‘Manzanilla Cacereña’ maintained higher oleic acid and stability, whereas ‘Morisca’ and ‘Pico Limón’ were more prone to phenolic compound loss and sensory deterioration at full ripeness. Multivariate analysis confirmed strong genotype × maturity interactions shaping oil quality. Optimal harvest timing must therefore be tailored to each cultivar to maximize phenolic content, oxidative stability, and sensory excellence while balancing industrial yield. Full article

The effect of cold atmospheric plasma (CAP) (a pin-to-liquid DBD) (28–32 kV, 1–10 min) on virgin olive oil (VOO) lipid oxidation was kinetically investigated. Quality assessment was performed (bioactive compound concentrations and fatty acid profiles) while the samples were further characterized by Fourier Transform Infrared (FTIR) spectroscopy and proton Nuclear Magnetic Resonance (¹H NMR). Intense processing (>5 min and voltages > 31 kV) significantly affected the quality of VOO, enhancing the oxidative reactions. CAP treatment led to an eight-fold increase in peroxide values and to a decrease in total antioxidants by up to 80% compared to untreated VOO. Carbonyl compounds (aldehydes, carboxylic acids) and hydroperoxide intermediates were the main oxidation products, while polyunsaturated fatty acids (PUFAs) dropped from 81.17% to 76.51%. The double bonds in the acyl chains were also highly reactive and facilitate the oxidation and subsequent fragmentation of the VOO. Full article

The objective of this study was to evaluate the impact of the material (plastic or glass) and color (green or colorless) of extra virgin olive oil (EVOO) and virgin olive oil (VOO) bottles on the acquisition of SORS spectra using portable equipment. Sixteen bottles of EVOO and three bottles of VOO were analyzed, including different volumes. A range of similarity indices was calculated between vial-reference (offline measurements) and bottles (online measurements), including R², COS θ, NEAR, and a new index called WSI (Weighted Similarity Index). WSI is calculated from the pondered linear combination of the previous three, and a threshold of >0.95 is established as high similarity. The results showed that plastic bottles, regardless of color and volume, and colorless glass bottles had WSI values > 0.95. In contrast, green glass bottles demonstrated a lower degree of similarity (WSI < 0.95), which impacted the reliability of their spectral fingerprints. A hierarchical cluster analysis (HCA) was performed by locating EVOO bottles according to their material in two clusters. A study of storage under optimal, non-optimal, and commercial conditions showed that both EVOO and VOO maintain highly similar spectral profiles for 10–18 days (WSI > 0.965), even in bottles purchased in supermarkets. These results demonstrate that the SORS technique is suitable for the direct analysis of olive oils in plastic and colorless glass containers, without the need to open the bottles. The SORS technique is a fast, reliable, non-invasive, and non-destructive tool for quality control of olive oil. Full article

This study examined the influence of short-term olive fruit storage on the quality of virgin olive oil (VOO) from three cultivars (‘Kalinjot’, ‘Leccino’, and ‘Frantoio’) grown in southwest Albania. Olive fruits were processed immediately after harvest, or after 10 days of storage under ambient conditions (20–22 °C) and refrigeration (5 °C). Oils were evaluated for physicochemical quality parameters (free acidity, peroxide value, and UV absorption indices), as well as bioactive and sensory-related compounds (bitterness index, chlorophylls, carotenoids, and total phenolic content). Results showed that immediate processing yielded the highest quality oils, with low free acidity (0.28–0.35%) and preserved bioactive compounds. Ambient storage led to marked deterioration, including significant increases in free acidity and peroxide values, loss of pigments, and 20–70% reduction in phenolic content, accompanied by decreased bitterness. In contrast, cold storage mitigated these effects, maintaining values closer to baseline and preserving sensory and functional attributes. ANOVA confirmed significant effects of storage duration, temperature, and cultivar on most parameters, with ‘Kalinjot’ exhibiting greater stability compared to ‘Frantoio’ and ‘Lecino’. These findings highlight that minimizing the interval between harvest and milling is critical for ensuring oil quality, while refrigerated storage offers a practical strategy to safeguard chemical and sensory characteristics when immediate processing is not feasible. Full article

This study investigated, for the first time, the effects of pulsed electric field (PEF) pretreatment—applied prior to malaxation at 2–7 kV/cm for 30–90—on oil yield, quality parameters, and volatile profiles of virgin olive oils (VOO) from four representative Croatian autochthonous varieties: Istarska Bjelica and Rosulja (Istria), and Levantinka and Oblica (Dalmatia). Mild PEF conditions significantly increased oil yield (2.5–36%), with the strongest effects observed in varieties with low baseline yields. Basic quality parameters were largely unaffected, but volatile organic compound (VOC) profiles were markedly altered. PEF increased VOCs from the lipoxygenase (LOX) pathway, particularly at lower field strengths, and altered their composition, suggesting changes in the activity of the enzymes involved in their biosynthesis. Among these enzymes, LOX was analyzed, and its activity responded to PEF treatment in a cultivar-dependent manner. Furthermore, PEF generally reduced minor VOCs associated with oxidation and microbial activity. These findings demonstrate the potential of PEF as a non-thermal, sustainable technology for improving oil extraction efficiency while simultaneously enhancing the aroma profile of VOOs. Full article

Extra virgin olive oil (EVOO) can degrade during production or storage to virgin olive oil (VOO) or lampante olive oil (LOO). Fraud can also occur during commercialisation through the adulteration of EVOO (Ad-EVOO) with cheaper sunflower oil (SFO). Therefore, rapid screening techniques for quality control are needed. We evaluated an electronic nose (EN) with chemometrics—linear discriminant analysis (LDA), artificial neural-network discriminant analysis (ANN-DA), and partial least-squares regression (PLS)—in two scenarios: (i) classification into four classes (EVOO, VOO, LOO, and Ad-EVOO adulterated with 25% w/w SFO); and (ii) Ad-EVOO series containing 5–40% w/w SFO. Classes were corroborated by HS-SPME-GC-MS, with elevated (E)-2-hexenal and 3-hexen-1-ol in EVOO and increases in nonanal, ethyl acetate, and 2-propanol in deteriorated oils. Using the EN, LDA separated the classes, and ANN-DA achieved 90% accuracy under cross-validation, with the greatest confusion between VOO and LOO. In adulteration, discrimination emerged from 20% SFO, and PLS estimated %Ad-EVOO with R²pred = 0.972 (RMSEC/RMSEP = 8.059/5.627). In conclusion, the EN provides objective, rapid, and non-destructive screening that supports sensory panels and chromatographic analyses during reception and storage in industrial settings. Full article

This study investigated the effects of ultrasonic treatment of olive paste prior to malaxation on oil yield (Y), enzyme activity and virgin olive oil (VOO) quality in four Croatian olive varieties: Istarska Bjelica, Rosulja, Oblica and Levantinka. The oils were extracted using the Abencor system according to a central composite experiment design, with treatment durations of 3–17 min and power levels of 256–640 W. The parameters analyzed included Y, oxidative stability index (OSI), antioxidant capacity (AC), phenolic and α-tocopherol content, volatile compounds, fatty acid profile, and the activity of lipoxygenase, β-glucosidase, polyphenol oxidase, and peroxidase. Olive variety was the most influential factor in all variables. The response surface methodology showed that ultrasonic treatment at low-to-medium intensity improved several quality attributes. For example, Y increased by 4% in Oblica, phenolic content increased by up to 17% in Istarska Bjelica, and OSI and AC increased by 13–15% in Istarska Bjelica and Levantinka. In contrast, longer treatment and higher ultrasound power had a negative effect. No significant differences were found in other parameters examined. Overall, the application of ultrasound led to measurable, though moderate, improvements in Y and VOO quality, with results strongly dependent on olive variety and treatment conditions. These results underline the need for further optimization tailored to each variety. Full article

Flash thermal pretreatment (FTT) is a promising technique for enhancing virgin olive oil (VOO) quality. This study investigated the effects of FTT, both cooling (15–25 °C) and heating (30–40 °C), on phenolics, tocopherols, fatty acid composition, oxidative stability (OSI), antioxidant capacity (AC), and volatile composition in VOOs from three Croatian varieties: Istarska Bjelica, Levantinka, and Oblica. A full factorial experimental design was used with two independent variables: treatment temperature and olive variety. Olive pastes were treated after crushing and before malaxation. Data were evaluated using ANOVA, partial least squares (PLS) regression, and response surface methodology (RSM). Istarska Bjelica showed the highest OSI improvement (+16%) mostly linked to elevated phenolic compounds. Levantinka exhibited moderate responses, with slight OSI and AC declines. Oblica was most sensitive to heating, showing OSI and AC reductions (up to 28%), despite increased oleocanthal and olacein. RSM identified optimal FTT temperatures for each variety: 18.9 °C (Istarska Bjelica), 15.4 °C (Levantinka), and 15.5 °C (Oblica). These findings support variety-specific FTT as an effective strategy to improve VOO functional and sensory quality. Full article

Introduction: Olive oil’s health benefits are widely known and extensively documented; its advantages are widespread, covering numerous areas of human health. Clinical and experimental data indicate that a Mediterranean Diet (MedDiet) with Extra Virgin Olive Oil (EVOO) lowers the risk of illnesses associated with oxidative stress, chronic inflammation, and weakened immunity, including cancer and cardiovascular disease (CVD). The European Food Safety Authority (EFSA) confirms that olive oil’s polyphenols help protect blood lipids against oxidative damage; thus, EVOO, crucial in the MedDiet, could be a functional food component. Olive oils must contain at least 5 mg of Hydroxytyrosol (HYTY) and its derivatives (oleuropein and Tyrosol (TY)) per 20 g to qualify for the EFSA-approved health claim. To provide a summary of clinical study results, this systematic review assessed the impact of Virgin olive oil (VOO) consumption on cardiovascular risk and disease prevention. Methods: The systematic review’s studies were collected from PubMed, Cochrane, Web of Science, and Scopus following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and the Population Intervention Comparison Outcome Population (PICO) framework. Results: Seventeen clinical studies were identified, which highlighted the association between VOO consumption (including EVOO) and a reduced risk of cardiovascular disease. Particularly, improvements in biomarkers involved in cardiometabolic pathways and subsequent cardiovascular events were recorded. The beneficial effect was attributed to the polyphenols contained in EVOO. Indeed, EVOO supplementation as part of the Mediterranean diet could improve patients’ quality of life in secondary prevention by demonstrating a positive correlation with the cardioprotective role of polyphenols. Discussion: A balanced diet with VOO represents a simple yet potent method to counteract metabolic dysfunctions associated with CVD. Despite these results, further multicenter clinical studies with a wider range of patients are required to confirm and better understand EVOO’s effects on the prevention of cardiovascular risk. Full article

Various protein-rich foods are traditionally immersed in virgin olive oil (VOO), a medium rich in phenols, which are health-promoting and sensorially important compounds. Immersing tofu in VOO may modify the sensory properties and nutritional value of both due to the oil’s hydrophilic phenol interactions with proteins and water. In this study, cubes of fresh tofu (T) (70% water) and freeze-dried tofu (FD-T) (5% water) were immersed in VOO for 7 days of cold storage. The changes in the phenolic compound content and standard quality parameters of the oil were noted after 1, 3, 5, and 7 days of contact with the tofu. The total phenols in the oil were determined using the Fast Blue BB assay, while single phenols were analyzed by HPLC-UV/VIS. During the 7 days, the total phenols in the oil decreased by up to 56% and 26% under the influence of fresh and freeze-dried tofu, respectively, including a significant decrease in hydroxytyrosol, oleacein, tyrosol, and oleocanthal. The water content and its release from fresh tofu significantly contributed to this decline. The degradation of the quality of the oil in contact with the fresh tofu was observed only in its sensory properties, with a marked reduction in the intensity of its fruitiness, bitterness and pungency. Full article

Extra virgin olive oil (EVOO) is one of the main daily food items consumed around the world, particularly in the Mediterranean region, and it has unique organoleptic properties. This study aims to determine the best frying conditions of EVOO supplemented with natural exogenous antioxidants enriched in hydroxytyrosol (HTyr) and its derivatives from olive fruit extract (OFE) to conserve its positive sensorial attributes while minimizing its sensorial defects, in particular, rancidity under high thermal processes. In this study, an experienced panel assessed the sensory attributes of nine EVOO varieties, olive oil 0.4° (mixed virgin olive oil (VOO) with refined olive oil (ROO)), Orujo olive oil, and olive oil 1° (EVOO mixed with ROO), compared with two sunflower oil types, performed using a deep-frying (D-F) process with numerous variables, i.e., frying time, frying temperature, and the addition of polyphenols enriched with HTyr. Results showed that most EVOO samples were stable under D-F at 170 °C for 3 h, with added polyphenols (∼650 mg/kg). Moreover, at these best values, the results stated that Arbequina, Picual, Royuella, Hojiblanca, Arbosana, and Manzanilla oils have low rancidity scores with values of 0, 1.7, 1.8, 2.3, 3.1, and 3.7, respectively, and stable/higher positive sensorial attributes, i.e., fruity, bitter, and pungent properties; however, olive oil 1° and olive oil 0.4° have high rancidity and low positive sensorial attributes. Notably, OFE helps maintain bitterness close to control in Picual, Koroneiki, Empeltre, and Arbosana oils. Furthermore, amongst the 19 tested sensory descriptors, only 8 descriptors—namely, fusty/muddy sediment, winey/vinegary/acid/sour, frostbitten olives (wet wood), rancid, fruity (green), fruity (ripe), bitter, and pungent—were successfully developed to allow characterization of the sensory quality of various olive oil categories under D-F. The present research confirmed that OFE may be used to provide stable EVOOs with higher positive sensorial qualities and lower defects and could be used as a natural antioxidant and promising strategy during the D-F process with EVOOs, not only for domestic practices but also at the industrial level. Full article

Virgin olive oil (VOO) is a globally esteemed product renowned for its chemical composition, nutritional value, and health benefits. Consumers seeking natural, nutritious, and healthy foods increasingly favor VOO. The optimization of the extraction system ensures the production of high-quality VOO with abundant antioxidant compounds that naturally protect it from degradation. Proper storage is crucial in maintaining the quality of VOO, prompting the exploration of novel extraction and preservation techniques. Factors such as light, temperature, and oxygen greatly influence the degradation process, resulting in reduced levels of natural antioxidants like polyphenols. Undesirable by-products and non-aromatic compounds may be formed, making the oil unacceptable over time. On the basis of all this consideration, this study aimed to evaluate the synergic use of two different gases (CO₂ and argon) during the malaxation phase to limit radical development and delay lipid autoxidation. Additionally, unconventional preservation systems, namely argon headspace, shellac, and bottle in bag, were assessed over a period of 150 days. The results evidenced that the use of CO₂ and argon during the malaxation process resulted in an improvement in the oil quality compared to the one obtained with the traditional system. However, in traditional oils, the alternative packaging systems determined interesting outcomes as they were able to positively affect different parameters, while the packaging effect was more mitigated in the test oils. Full article

Olive anthracnose, caused by Colletotrichum fungi, and the olive fruit fly Bactrocera olea are, respectively, the most important fungal disease and pest affecting olive fruits worldwide, leading to detrimental effects on the yield and quality of fruits and olive oil. This study focuses on the content of hydroxytyrosol (HYT) and its derivatives (the “olive oil polyphenols” health claim) in olive oils extracted from fruits of ‘Galega Vulgar’ and ‘Cobrançosa’ cultivars, naturally affected by olive anthracnose and olive fly. The olives, with different damage levels, were harvested from organic rainfed orchards, located in the center of Portugal, at four harvest times over three years. Galega oils extracted from olives with a higher anthracnose and olive fly incidence showed no conformity for the extra virgin olive oil (EVOO) and virgin olive oil (VOO) categories, presenting high acidity and negative sensory notes accompanied by the disappearance of oleacein. Conversely, no sensory defects were observed in Cobrançosa oils, regardless of disease and pest incidence levels, and quality criteria were still in accordance with the EVOO category. The total HYT and tyrosol (TYR) content (>5 mg/20 g) allows for the use of the “olive oil polyphenols” health claim on the label of all the analyzed Cobrançosa olive oils. Full article

The electronic nose is a non-invasive technology suitable for the analysis of edible oils. One of the practical applications in the olive oil industry is the classification of virgin oils based on their sensory characteristics. Notwithstanding that this technology, at this stage, cannot realistically replace the currently used methods, it is fruitful for a preliminary analysis of the oil quality. This work makes use of this technology to develop a methodology for the detection of the threshold by which an extra-virgin olive oil (EVOO) drops into the virgin olive oil (VOO) category. With this aim, two features were studied: the level of fruitiness level and the type of defect. The results showed a greater influence of the level of fruitiness than the type of defect in the determination of the detection threshold. Furthermore, three of the sensors (S2, S7 and S9) of the commercial e-nose PEN3 were identified as the most discriminating in the classification between EVOO and VOO oils. Full article

The Selçuk district of Izmir is one of the most essential regions in terms of olive oil production. In this study, 60 olive oil samples were obtained from five different locations (ES: Eski Şirince Yolu, KK: Kınalı Köprü, AU: Abu Hayat Üst, AA: Abu Hayat Alt, and DB: Değirmen Boğazı) in the Selçuk region of Izmir during two (2019–2020 and 2020–2021) consecutive cropping seasons. Quality indices (free acidity, peroxide value, p-Anisidine value, TOTOX, and spectral absorption at 232 and 270 nm) and the fatty acid, phenolic, and sterol profiles of the samples were determined to analyze the changes in the composition of Selcuk olive oils according to their growing areas. When the quality criteria were analyzed, it was observed that KK had the lowest FFA (0.11% oleic acid, PV (6.66 meq O₂/kg), p-ANV (11.95 mmol/kg), TOTOX (25.28), and K232 (1.99) values and K270 had the highest value. During the assessment of phenolic profiles, the ES group exhibited the highest concentration of the phenolic compound p-HPEA-EDA (oleocanthal), with a content of 93.58 mg/kg, equivalent to tyrosol. Upon analyzing the fatty acid and sterol composition, it was noted that AU displayed the highest concentration of oleic acid (71.98%) and β-sitosterol (87.65%). PCA analysis illustrated the distinct separation of the samples, revealing significant variations in both sterol and fatty acid methyl ester distributions among oils from different regions. Consequently, it was determined that VOOs originating from the Selçuk region exhibit distinct characteristics based on their geographical locations. Hence, this study holds great promise for the region to realize geographically labeled VOOs. Full article