Commercial Extra Virgin Olive Oils Research Articles

Molecular Traceability Approach to Assess the Geographical Origin of Commercial Extra Virgin Olive Oil

Extra virgin olive oil (EVOO) is a precious and healthy ingredient of Mediterranean cuisine. Due to its high nutritional value, the interest of consumers in the composition of EVOO is constantly increasing, making it a product particularly exposed to fraud. Therefore, there is a need to properly valorize high-quality EVOO and protect it from fraudulent manipulations to safeguard consumer choices. In our study, we used a straightforward and easy method to assess the molecular traceability of 28 commercial EVOO samples based on the use of SSR molecular markers. A lack of correspondence between the declared origin of the samples and the actual origin of the detected varieties was observed, suggesting possible adulteration. This result was supported by the identification of private alleles based on a large collection of national and international olive varieties and the search for them in the molecular profile of the analyzed samples. We demonstrated that the proposed method is a rapid and straightforward approach for identifying the composition of an oil sample and verifying the correspondence between the origin of olives declared on the label and that of the actual detected varieties, allowing the detection of possible adulterations.

Evaluating Adulteration of Commercial Extra Virgin Olive Oil with Canola and Sunflower Oils Through Electrochemical Impedance Spectroscopy

Evaluating Adulteration of Commercial Extra Virgin Olive Oil with Canola and Sunflower Oils Through Electrochemical Impedance Spectroscopy

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.

Development of a Chemically Modified Sensor Based on a Pentapeptide and Its Application for Sensitive Detection of Verbascoside in Extra Virgin Olive Oil.

In addition to their antioxidant and antimicrobial action in functional foods, beverages, and in some dermato-cosmetic products, olive phenolic compounds are also recognized for their role in the prevention of diabetes and inflammation, treatment of heart disease and, consequently, of the numerous chronic diseases mediated by the free radicals. In recent years, attention has increased, in particular, regarding one of the most important compound in extra virgin olive oil (EVOO) having glycosidic structure, namely verbocoside, due to the existence in the literature of numerous studies demonstrating its remarkable contribution to the prophylaxis and treatment of various disorders of the human body. The purpose of this study was the qualitative and quantitative determination of verbascoside in commercial EVOOs from different regions by means of a newly developed sensor based on a screen-printed carbon electrode (SPCE) modified with graphene oxide (GPHOX), on the surface of which a pentapeptide was immobilized by means of glutaraldehyde as cross-linking agent. The modified electrode surface was investigated using both Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) methods. This newly developed sensor has shown a high sensibility compared to the unmodified electrode, a low detection limit (LOD) of up to 9.38 × 10-8 M, and a wide linearity range between 0.1 µM and 10.55 µM. The applicability of the modified sensor was confirmed by detecting verbascoside in ten different EVOOs samples using the cyclic voltammetry (CV) method, with very good results. The validation of the electroanalytical method was performed by using the standard addition method with very good recoveries in the range of 97.48-103.77%.

Studies on the Detection of Oleuropein from Extra Virgin Olive Oils Using Enzymatic Biosensors.

Oleuropein (OLEU) is an important indicator of the quality and authenticity of extra virgin olive oils (EVOO). Electrochemical sensors and biosensors for the detection of oleuropein can be used to test the adulteration of extra virgin olive oils. The present study aimed at the qualitative and quantitative determination of oleuropein in commercial EVOO samples by applying electrochemical techniques, cyclic voltammetry (CV) and square wave voltammetry (SWV). The sensing devices used were two newly constructed enzyme biosensors, supported on single-layer carbon-nanotube-modified carbon screen-printed electrode (SPE/SWCNT) on whose surface tyrosinase (SPE/SWCNT/Tyr) and laccase (SPE/SWCNT/Lac) were immobilized, respectively. The active surfaces of the two biosensors were analyzed and characterized by different methods, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Fourier transform infrared spectroscopy (FTIR) and the results confirmed the efficient immobilization of the enzymes. SPE/SWCNT/Tyr was characterized by a low detection limit (LOD = 9.53 × 10−8 M) and a very good sensitivity (0.0718 μA·μM−1·cm−2) over a wide linearity range from 0.49 to 11.22 μM. The process occurring at the biosensor surface corresponds to kinetics (h = 0.90), and tyrosinase showed a high affinity towards OLEU. The tyrosinase-based biosensor was shown to have superior sensitive properties to the laccase-based one. Quantitative determination of OLEU in EVOOs was performed using SPE/SWCNT/Tyr and the results confirmed the presence of the compound in close amounts in the EVOOs analysed, proving that they have very good sensory properties.

Quality assessment and geographical origin classification of extra-virgin olive oils imported into China

Extra-virgin olive oil (EVOO) is an important imported commercial product in China. This study comprehensively evaluated the quality of EVOOs imported from different countries into China based on chemical parameters and sensory attributes. Multivariate statistics were used to authenticate their geographical origins. 71.8% of the oils failed to meet the current official standards at inland and abroad established for commercial EVOO category. Pyropheophytin, defect attributes, peroxide value, and K270 were above the limits in 32%, 24%, 23%, and 5% of the failed samples respectively, while free acidity, K232 and delta K were above the limits in 4%. Fatty acids and delta ECN42 were beyond the limits in 2% of the failed samples. Linear discriminant analysis (LDA) and orthogonal partial least squares discriminant analysis (OPLS-DA) based on fatty acids and triacyglycerols succeeded in identifying the origin of olive oils. 3.5% of the total might be mislabelled the geographical origin. The main quality problems of the analyzed oils include oxidation, counterfeiting with refined oils and origin fraud. Considering the results and the fact that most EVOOs in China are imported from other countries, chemometrics combined with critical quality attributes should be an ideal way of EVOO quality control, protecting consumers from frauds.

Sensitive Detection of Hydroxytyrosol in Extra Virgin Olive Oils with a Novel Biosensor Based on Single-Walled Carbon Nanotubes and Tyrosinase.

Hydroxytyrosol (HT) is an important marker for the authenticity and quality assessment of extra virgin olive oils (EVOO). The aim of the study was the qualitative and quantitative determination of hydroxytyrosol in commercial extra virgin olive oils of different origins and varieties using a newly developed biosensor based on a screen-printed electrode modified with single-layer carbon nanotubes and tyrosinase (SPE-SWCNT-Ty). The enzyme was immobilized on a carbon-based screen-printed electrode previously modified with single-layer carbon nanotubes (SPE-SWCNT-Ty) by the drop-and-dry method, followed by cross-linking with glutaraldehyde. The modified electrode surface was characterized by different methods, including electrochemical (cyclic voltammetry (CV), differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS)) and spectrometric (Fourier transform infrared (FTIR) spectroscopy) methods. Cyclic voltammetry was used for the quantitative determination of HT, obtaining a detection limit of 3.49 × 10−8 M and a quantification limit of 1.0 × 10−7 M, with a wide linearity range (0.49–15.602 µM). The electrochemical performance of the SPE-SWCNT-Ty biosensor was compared with that of the modified SPE-SWCNT sensor, and the results showed increased selectivity and sensitivity of the biosensor due to the electrocatalytic activity of tyrosinase. The results obtained from the quantitative determination of HT showed that commercial EVOOs contain significant amounts of HT, proving the high quality of the finished products. The determination of the antiradical activity of HT was carried out spectrophotometrically using the free reagent galvinoxyl. The results showed that there is a very good correlation between the antiradical capacity of EVOOs, the voltammetric response and implicitly the increased concentration of HT. SPE-SWCNT-Ty has multiple advantages such as sensitivity, selectivity, feasibility and low cost and could be used in routine analysis for quality control of food products such as vegetable oils.

Analyzing the Organoleptic Quality of Commercial Extra Virgin Olive Oils: IOC Recognized Panel Tests vs. Electronic Nose.

Virgin olive oil (VOO) classification into quality categories determines its labeling and market price. This procedure involves performing a series of chemical–physical analyses and, ultimately, a sensory analysis through the panel test. This work explores the analysis of VOOs quality with an electronic olfactory system (EOS) and examines its abilities using the panel test as a reference. To do this, six commercial olive oils labelled as extra virgin were analyzed with an EOS and classified by three panels recognized by the International Olive Council. The organoleptic analysis of the oils by the panels indicated that most of the oils in the study were in fact not extra virgin. Besides this, the classifications showed inconsistencies between panels, needing statistical treatment to be used as a reference for the EOS training. The analysis of the same oils by the EOS and their subsequent statistical analysis by PCA revealed a good correlation between the first principal component and the olive oil quality from the panels using average scores. It also showed a more consistent classification than the panels. Overall, the EOS proved to be a cheaper, faster, and highly reliable method as a complement to the panel test for the olive oil classification.

Digital Detection of Olive Oil Rancidity Levels and Aroma Profiles Using Near-Infrared Spectroscopy, a Low-Cost Electronic Nose and Machine Learning Modelling

The success of the olive oil industry depends on provenance and quality-trait consistency affecting the consumers' acceptability/preference and purchase intention. Companies rely on laboratories to analyze samples to assess consistency within the production chain, which may be time-consuming, cost-restrictive, and untimely obtaining results, making the process more reactive than predictive. This study proposed implementing digital technologies using near-infrared spectroscopy (NIR) and a novel low-cost e-nose to assess the level of rancidity and aromas in commercial extra-virgin olive oil. Four different olive oils were spiked with three rancidity levels (N = 17). These samples were evaluated using gas-chromatography-mass-spectroscopy, NIR, and an e-nose. Four machine learning models were developed to classify olive oil types and rancidity (Model 1: NIR inputs; Model 2: e-nose inputs) and predict the peak area of 16 aromas (Model 3: NIR; Model 4: e-nose inputs). The results showed high accuracies (Models 1–2: 97% and 87%; Models 3–4: R = 0.96 and 0.93). These digital technologies may change companies from a reactive to a more predictive production of food/beverages to secure product quality and acceptability.

Microbiological and Enzymatic Activity Modulates the Bitter Taste Reduction in Decanted Coratina Olive Oil.

Coratina monocultivar extra virgin olive oil (EVOO) is known for its level of bitterness, which, if too high, can cause consumer acceptance problems. The aim of this study was to modulate the bitter taste of freshly produced olive oil through endogenous enzymatic activity and microbiota during the decantation phase. The opalescent appearance of the newly produced EVOO was substantially reduced during the first three months of decantation due to the deposition of more than 90% of suspended material, consisting of vegetation water and suspended solid particles. The high content of biophenols and the reduction in water concentration in the oil samples negatively affected the survival of yeasts, which were absent in the oil samples at the end of the third month of decantation. The oleuropeinolytic activity was very intense during the first month of decantation, whereas the reduction in the bitter taste associated with the aglycons was consistent only in the second and third months of decantation. At the end of decantation, the sensory notes of bitterness in the Coratina EVOO were reduced by 33%, lowering the position on the value scale without altering the other qualitative parameters whose values fell within the limits of the commercial EVOO class.

Detection of soft-refined oils in extra virgin olive oil using data fusion approaches for LC-MS, GC-IMS and FGC-Enose techniques: The winning synergy of GC-IMS and FGC-Enose

Extra virgin olive oil (EVOO) is frequently adulterated by mixing it with soft refined oils (SROO). The differentiation of EVOO from its blends with SROO is not possible with the most common approaches, and, for this reason, the discriminating power of liquid chromatography-high resolution mass spectrometry (LC-MS), gas-chromatography ion mobility spectrometry (GC-IMS) and flash gas-chromatography electronic nose (FGC-Enose) was examined previously. Here, the combination of the above-mentioned techniques for an improvement in classification power of the methods is explored. A total of 43 commercial EVOOs and 18 illegal mixtures of SROO with EVOO were previously analysed by LC-(+/−)MS, GC-IMS and FGC-Enose. Low-level and mid-level data fusion of the four datasets were performed. The merged unique fingerprints were submitted to partial least squared discriminant analysis (PLS-DA), and the extrapolated most informative variables were used to build support vector machine (SVM) classifiers. Statistical indicators were calculated and compared to find out the best classifier. The results of PLS-DA-SVM strategies on the combination of datasets demonstrated that, after low-level data fusion, the discriminatory capability of the two merged GC-based techniques was remarkably improved as compared to the individual techniques. This indicates that merging the datasets before PLS-DA better retrieves the most informative variables and, thus, enhances group separation and classification of unknowns. The combination of LC(+/−)MS datasets, both by mid- and low-level data fusion, did not show significant enhancement in terms of discrimination of EVOO from SROO as compared to the individual LC(+)MS matrix. The low-level combination of the four datasets (LC(+/−)MS, GC-IMS, FGC-Enose) was successful, although this laborious option is not a viable path in industry quality assurance. This study primarily provides new paths for the authentication of EVOO, taking advantage of merging multimodal LC-(+/−)MS, GC-IMS and FGC-Enose data, with consequent improvement in the performances of the classification models. The most promising results were achieved by the low-level data fusion of GC-IMS and FGC-Enose data.

Oleuropein from olive leaf extracts and extra-virgin olive oil provides distinctive phenolic profiles and modulation of microbiota in the large intestine

The interest in the modulation of gut microbiota by polyphenols from olives and derived products is increasing. In this work, phenolic leaf extracts (PLE) were in vitro faecal fermented to evaluate the changes in phenolic profiles and the impact on microbiota, using a commercial extra-virgin olive oil (EVOO) as reference. The in vitro fermentation decreased oleuropein content in PLE, determining an increase of hydroxytyrosol and other phenolic metabolites. An increase (p < 0.05) of hydroxytyrosol (LogFC = 6.02; VIP score = 1.05) was also observed in fermented EVOO. Besides, PLE significantly (p < 0.05) changed amino acids (LogFC = 6.1) and fatty acids (LogFC = 5.9) profile of the faeces. Metagenomic sequencing revealed that Coriobacteriaceae at the family level, and Collinsella at the genus level, were the most affected by PLE fermentation. These findings support the modulation of the gut microbiota exerted by phenolics from PLE and EVOO.

Use of portable Raman spectroscopy in the quality control of extra virgin olive oil and adulterated compound oils

The practice of defrauding food and other consumer goods is growing in recent years, and products with high added value are the main targets of this practice, such as extra virgin olive oil (EVOO). In this paper, we evaluated eight samples of EVOO and four samples of compound oils (blends of soybean oil with EVOO) of different commercial brands. For this, we used the portable Raman spectroscopy in the region of 800 to 1800 cm−1, aiming to identify the adulteration of EVOO using soybean oil. Analytical curves were constructed with different concentrations, ranging from 0 to 100 wt% of vegetable oil in EVOO to build regression models. They were developed by chemometric tools, as partial least squares (PLS) and partial least squares by intervals (iPLS). Besides, a univariate model was elaborated based on the ratio of the bands 1440 cm−1 (CH2) and 1655 cm−1 (CC). These models were applied to predict the concentration of adulterant in twelve commercial samples. The iPLS method presented the best analytical results, with R2p of the 0.9967 and RMSEP of 0.0198 wt%, in addition to the limits of detection and quantification of 0.9731 and 3.2436 wt%, respectively. Among the commercial samples evaluated, seven presented higher soybean oil concentrations than the manufacturer's label, thus characterizing the adulteration of the product. Principal component analysis (PCA) was also used to qualitatively evaluate the degree of similarity between commercial EVOO samples, blends, and vegetable oils. The combination of the portable analytical technique with the chemometric methods allowed the identification and quantification, in loco, of adulterants present in commercial EVOO samples.

Evaluating Quality Parameters, the Metabolic Profile, and Other Typical Features of Selected Commercial Extra Virgin Olive Oils from Brazil

The production of extra virgin olive oil (EVOO) in Brazil developed quite recently, and information on commercial Brazilian EVOO’s typical features is very scarce. In just one of the previously published works on Brazilian olive oil, the assessed samples were commercially available. In this study, a comprehensive characterization of EVOO samples acquired at local stores (at Rio de Janeiro and Rio Grande do Sul, from the two most prevalent cultivars, Arbequina and Koroneiki) was carried out considering the most relevant quality parameters, antioxidant capacity, oxidative stability, total phenolic content, fatty acid composition, and minor component metabolic profiling. The latter included: (1) the determination of individual phenolic compounds (belonging to four diverse chemical classes) and triterpenic acids by means of a powerful multi-class reversed-phase LC-MS method; (2) the quantitative profiling of tocopherols, phytosterols, and pigments by normal-phase LC-DAD/fluorescence; and (3) the quantitative appraisal of the volatile pattern of the oils by solid-phase microextraction (SPME)-gas chromatography (GC)-MS. By applying these methods, the concentrations of approximately 70 minor compounds were determined in commercial EVOOs from Brazil. To the best of our knowledge, the content of a very large number of phenolic compounds of those determined in the current report (mainly secoiridoids), the three triterpenic acids (maslinic, betulinic, and oleanolic acids), and the individual chlorophyll derivatives had not been previously evaluated in Brazilian EVOOs. The present work provides a broad picture of the compositional profile and other parameters of relevance of selected commercial Brazilian EVOOs available on local markets, describing their typicity and most particular features, some of which are known to have potential impacts on consumers’ health.

Metabolomic Study to Evaluate the Transformations of Extra-Virgin Olive Oil's Antioxidant Phytochemicals During In Vitro Gastrointestinal Digestion.

In this work, different commercial extra-virgin olive oils (EVOO) were subjected to in vitro gastrointestinal digestion and the changes in bioactive compounds were evaluated by ultra-high-pressure liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry, using untargeted metabolomics. As expected, raw EVOO samples were abundant in total sterols (on average: 3007.4 mg equivalents/kg) and tyrosol equivalents (on average: 334.1 mg equivalents/kg). However, the UHPLC-QTOF screening allowed us to annotate 309 compounds, with a large abundance of sterols (219 compounds), followed by polyphenols (67 compounds) and terpenoids. The in vitro gastrointestinal digestion was found to affect the phytochemical composition of the different EVOO samples. In particular, both unsupervised and supervised statistics depicted the modifications of the bioactive profile following gastric and pancreatic phases. Overall, the compounds which resulted as the most affected by the in vitro digestion were flavonoids (cyanidin and luteolin equivalents), whilst relatively high % bioaccessibility values were recorded for tyrosol equivalents during the pancreatic phase (on average, 66%). In this regard, oleuropein-aglycone (i.e., the major phenolic compound in EVOO) was converted to hydroxytyrosol, moving from an average value of 1.3 (prior to the in vitro digestion) up to 9.7 mg equivalents/kg during the pancreatic step. As proposed in the literature, the increase in hydroxytyrosol might be the result of the combined effect of lipase(s) activity and acidic conditions. Taken together, the present findings corroborate the suitability of untargeted metabolomics coupled to in vitro digestion methods to investigate the bioaccessibility of phenolic compounds. In this regard, a significant impact of in vitro gastrointestinal digestion on polyphenolic profiles has been detected, thus suggesting the need to account for actual bioaccessibility values rather than just considering the amounts in the raw commodity.

Evaluation of Chemical Properties of Commercial Extra Virgin Olive Oil in China.

The aim of the study was to investigate the chemical properties of the most popular commercial extra virgin olive oils (EVOOs) in China. A total of 14 EVOO samples were collected and evaluated, and significant differences were observed with respect to physicochemical properties, fatty acid composition, minor components, and the oxidation stability index (OSI). The results showed that the chemical properties of EVOOs were significantly affected by different producing areas. The oleic acid (C18:1) content (average value: 77.80%), squalene content (average value: 6052.28 mg/kg), and OSI (average value: 9.90 h) of the Spanish olive oil were higher than those of the other oils investigated, while the total phenolic content (average value: 308.34 mg/kg) was the lowest. Greek EVOOs had the lowest total sterol content (average value: 1023.48 mg/kg) and OSI (average value: 4.22 h). The C18:1 content (66.42%) and squalene content (3173.42 mg/kg) of the EVOO from China were lower than those of the other oils, while the palmitic acid (C16:0, 16.82%), linoleic acid (C18:2, 12.18%), total phenolic (553.17 mg/kg), and total sterol content (1904.77 mg/kg) were higher than those of the other olive oils. The EVOOs of the various countries could be distinguished by hierarchical cluster analysis (HCA). In addition, multiple linear regression (MLR) analyses between the OSI and chemical properties revealed that squalene (R = 0.729) and the unsaturation determined by the specific UV adsorption at 232 nm (K232, R = -0.300) were the main factors to affecting the EVOO oxidation stability.

A Simple Screening Method for Extra Virgin Olive Oil Adulteration by Determining Squalene and Tyrosol.

A simple screening method for discrimination between commercial extra virgin olive oils and their blends with other vegetable oils was developed. Squalene, which was contained relatively high amounts in virgin olive oil, was determined by HPLC after a simple pretreatment that was carried out by dilution of oil samples with 2-propanol. Tyrosol, which was contained at relatively high concentration in virgin olive oil among phenolic compounds, was determined by HPLC after a simple liquid-liquid extraction. When using squalene and tyrosol contents as axes, extra virgin olive oils could be discriminated from pure olive oils, blended oils (extra virgin olive oils with sunflower oil or grapeseed oil) and other vegetable oils. These results suggest that determining squalene and tyrosol in seed oil samples could be useful in distinguishing between extra virgin olive oil and blended oils as a screening method.

Extra Virgin Olive Oil Quality as Affected by Yeast Species Occurring in the Extraction Process.

In extra virgin olive oil (EVOO) extraction process, the occurrence of yeasts that could affect the quality of olive oil was demonstrated. Therefore, in this work, at first, the yeasts occurring during different extractive processes carried out in a Tuscany oil mill, at the beginning, in the middle, and the end of the harvesting in the same crop season, were quantified. Then, possible effects on quality of EVOO caused by the predominant yeast species, possessing specific enzymatic activities, were evaluated. Yeast concentrations were higher in extraction processes at the end of the harvesting. Twelve yeast species showing different isolation frequencies during olive oil extractive process and according to the harvesting date were identified by molecular methods. The yeast species dominating olive oil samples from decanter displayed enzymatic activities, potentially affecting EVOO quality according to zymogram analysis. HS-SPME-GC-MS analysis of the volatile compounds in commercial EVOO, inoculated with three yeast species (Nakazawaea molendini-olei, Nakazawaea wickerhamii, Yamadazyma terventina), pointed out significant differences depending on the strain inoculated. In conclusion, during the olive oil extractive processes, some yeast species colonize the extraction plant and may influence the chemical and sensory characteristics of EVOO depending on the cell concentrations and their enzymatic capabilities.

Determination of the Thermal Oxidation Stability and the Kinetic Parameters of Commercial Extra Virgin Olive Oils from Different Varieties

The use of olive oil with cooking purposes, as final seasoning or within cooked foods is increasing worldwide due to its numerous nutritional and health benefits. These attributes are mainly determined by olive oil chemical composition, which can be altered after thermal processing, oxidation processes, or incorrect practices. For this reason, and due to the numerous factors which have influence in olive oil quality, the correct chemical characterization is highly relevant. In this study, fatty acid composition of four extra virgin olive oil (EVOO) varieties was studied. The major fatty acid (FA) determined was oleic acid (77.1% on average), followed by palmitic (11.5% on average). In addition, thermal oxidation behaviour of the four EVOO samples was studied as an indicator of their quality and stability during thermal processing. This was performed through differential scanning calorimetry (DSC) from a temperature of 40°C at six different heating rates in the range of 0.5–10°C min−1. DSC records showed the same pattern and a small shoulder in the thermo-oxidation peak was present for all samples and all heating rates. The presence of initial and final oxidation products (by monitoring K232 and K270 values, respectively) was discarded according to the International Olive Council method.

Effect of Light Exposure on the Quality and Phenol Content of Commercial Extra Virgin Olive Oil during 12‐Month Storage

AbstractStorage conditions influence the maximum time for which the composition and sensory characteristics of olive oils can be guaranteed. The purpose of this research was to study the quality and phenol content of extra virgin olive oil (EVOO) after storage for 1 year in different types of containers under darkness or light. Three Spanish cultivars with quantitatively different phenol contents were selected for the study. Storage under light conditions impaired the physicochemical and sensorial properties of the three cultivars, and reduced total phenolics, but there was an increase in hydroxytyrosol and tyrosol concentrations. It also markedly decreased their total phenolic content, especially when kept in polyethylene containers exposed to light, with reductions ranging from 4.28% for vanillic acid in Picual oils stored in dark glass containers under dark conditions to 97.82% for ferulic acid in Arbequina oils stored in polyethylene containers under light conditions. There was a reduced concentration of flavonoid and lignan concentrations after 1 year of storage, with the greatest decrease (98.01% of initial content) being observed for in the flavonoid apigenin. These results indicate that EVOO should be stored in dark glass containers under dark conditions for the optimal preservation of its quality and phenol content.