Comparative Evaluation of Different Targeted and Untargeted Analytical Approaches to Assess Greek Extra Virgin Olive Oil Quality and Authentication.

Extra virgin olive oil (EVOO) is a key component of the Mediterranean diet, with several health benefits derived from its consumption. Moreover, due to its eminent market position, EVOO has been thoroughly studied over the last several years, aiming at its authentication, but also to reveal the chemical profile inherent to its beneficial properties. In the present work, a comparative study was conducted to assess Greek EVOOs' quality and authentication utilizing different analytical approaches, both targeted and untargeted. 173 monovarietal EVOOs from three emblematic Greek cultivars (Koroneiki, Kolovi and Adramytiani), obtained during the harvesting years of 2018-2020, were analyzed and quantified as per their fatty acids methyl esters (FAMEs) composition via the official method (EEC) No 2568/91, as well as their bioactive content through liquid chromatography coupled to high resolution mass spectrometry (LC-HRMS) methodology. In addition to FAMEs analysis, EVOO samples were also analyzed via HRMS-untargeted metabolomics and optical spectroscopy techniques (visible absorption, fluorescence and Raman). The data retrieved from all applied techniques were analyzed with Machine Learning methods for the authentication of the EVOOs' variety. The models' predictive performance was calculated through test samples, while for further evaluation 30 commercially available EVOO samples were also examined in terms of variety. To the best of our knowledge, this is the first study where different techniques from the fields of standard analysis, spectrometry and optical spectroscopy are applied to the same EVOO samples, providing strong insight into EVOOs chemical profile and a comparative evaluation through the different platforms.

Evaluation of Olive Oil Quality with Electrochemical Sensors and Biosensors: A Review.

Electrochemical sensors, sensor arrays and biosensors, alongside chemometric instruments, have progressed remarkably of late, being used on a wide scale in the qualitative and quantitative evaluation of olive oil. Olive oil is a natural product of significant importance, since it is a rich source of bioactive compounds with nutritional and therapeutic properties, and its quality is important both for consumers and for distributors. This review aims at analysing the progress reported in the literature regarding the use of devices based on electrochemical (bio)sensors to evaluate the bioactive compounds in olive oil. The main advantages and limitations of these approaches on construction technique, analysed compounds, calculus models, as well as results obtained, are discussed in view of estimation of future progress related to achieving a portable, practical and rapid miniature device for analysing the quality of virgin olive oil (VOO) at different stages in the manufacturing process.

Attitudes towards Olive Oil Usage, Domestic Storage, and Knowledge of Quality: A Consumers' Survey in Greece.

Consumption of unbranded olive oil obtained in bulk has previously been reported to be very high in Greece, underlining the need to investigate knowledge regarding its health attributes and storage practices, two areas that can affect oil quality. This study aimed to investigate Greek consumers' use and choice of olive oil, their knowledge about its quality, as well as domestic storage practices of olive oil. A cross-sectional survey was conducted in a representative sample of 857 Greek households that consume olive oil, using a previously validated questionnaire. Most participating households use olive oil produced by themselves or by their extended family or friends (60.3%), and only 27.4% purchase branded olive oil, while 57% reported using extra virgin olive oil (EVOO). Only 38.4% of the respondents reported optimal domestic storage practices to maintain olive oil quality, with a significant greater percentage of non-producers group compared to olive oil producers. In all areas of Greece, the higher the knowledge of olive oil quality, the higher the probability of consumers selecting EVOO and perceiving olive oil price as low. The present survey highlights the need to heighten consumers' knowledge of olive oil attributes and correct storage practices and awareness about branded EVOO and its superior quality.

Isotopic Traceability (13C and 18O) of Greek Olive Oil.

In recent years, isotopic analysis has been proven a valuable tool for the determination of the origin of various materials. In this article, we studied the 18O and 13C isotopic values of 210 olive oil samples that were originated from different regions in Greece in order to verify how these values are affected by the climate regime. We observed that the δ18O isotopic values range from 19.2 ‱ to 25.2 ‱ and the δ13C values range from -32.7 ‱ to -28.3 ‱. These differences between the olive oils' isotopic values depended on the regional temperature, the meteoric water, and the distance from the sea. Furthermore, we studied the 13C isotopic values of biophenolic extracts, and we observed that they have same capability to differentiate the geographic origin. Finally, we compared the isotopic values of Greek olive oils with samples from Italy, and we concluded that there is a great dependence of oxygen isotopes on the climatic characteristics of the different geographical areas.

Evaluating the Variability in the Phenolic Concentration of Extra Virgin Olive Oil According to the Commission Regulation (EU) 432/2012 Health Claim.

The health benefits of extra virgin olive oil (EVOO) are associated to its fatty acids profile (with predominance of oleic acid) and to the minor components that include phenols, among others. Phenols are responsible for the only health claim of olive oil reported in the Commission Regulation (EU) 432/2012. Here, we have applied a liquid chromatography-tandem mass spectrometry method to determine the most abundant phenols included in the health claim (with special emphasis on secoiridoids) in 1239 EVOO samples produced in two consecutive agronomical seasons. The predominant cultivars in Spain ("Picual", "Arbequina", "Hojiblanca", and "Cornicabra") were evaluated. We also studied the influence of harvesting date and orchard location on the EVOO phenolic concentration. A great variability in phenolic content, from 1 to 2850 mg/kg, was found in these EVOOs, and not all of them (4.6 and 23.1% in the two seasons) reported a concentration above 250 mg/kg to certify the health claim.

Chemical Profiles of Twenty-three Monovarietal Olive Oils Produced in Liangshan Region of China.

The main objective of this study was to differentiate twenty-three monovarietal olive oils produced in China (Azappa, Thiaki, Leucocarpa ovoid, manzanillo de labata, etc.) by studying their physicochemical properties, fatty acid profiles and oxidative stability. The majority of analytical indicators had statistically significant differences (p < 0.05). The tested cultivars produced excellent olive oils with an appreciable amount of natural antioxidants and chemical composition within the legal range. Our results demonstrate that Leucocarpa ovoid oil was characterized by high mean levels of total phenols (401.8 mg/kg), oleic acid (79.62%) and oxidative stability (18.64 h). Additionally, five types of olive oil were selected due to their high overall quality. Investigation of virgin olive oils indicates that the differences in the fatty acid profiles, phenols, sterols and tocopherols may be caused by genetic factors. The principal components analysis (PCA) results showed a strong differentiation between various cultivars in regard to their fatty acid composition and phenol, sterol and tocopherol levels. These components can be effective tools for efficient comparison and differentiation of these cultivars. To the best of our knowledge, this is the first work on the differentiation of the chemical constituents of virgin olive oils.

Homogeneity assessment of reference materials for sensory analysis of liquid foodstuffs. The virgin olive oil as case study.

Sensory properties are critical characteristics that determine quality and can be evaluated by trained tasting panels. The panels function as multi-sensor measuring instrument and need the use of reference materials (RMs) for training. The homogeneity between units packaged from a batch of RM can be evaluated by gas chromatography coupled to flame ionization detection (GC-FID), using this instrumental technique as an alternative to sensory analysis. For this purpose, the fingerprint methodology is applied, taking into account that the homogeneity assessment will be based on evaluating the similarity between the fingerprints of the fraction of volatile organic compounds acquired from samples representative of the batch. The proposed methodology is applied with good results to evaluate the homogeneity of several RMs for sensory analysis of virgin olive oil samples, using similarity indices, control charts and exploratory analysis of multivariate data to observe the grouping RM and fingerprint regions representative of each defect.

Effect of storage on quality parameters and phenolic content of Italian extra-virgin olive oils.

The quality of extra virgin olive oils is affected mainly by hydrolytic and oxidative reactions. The present paper investigated the changes of major and minor components and oxidation indices of three monovarietal extra virgin olive oils after 18 months of storage at room temperature and in dark glass bottles conditions. After storage, the basic quality parameters such as free acidity, peroxide values, extinction coefficients, fatty acids composition, chlorophyll and carotenoid content, did not exceed the upper limits set by European Community Regulations for extra-virgin olive oils. Given the importance of the phenolic fraction, UHPLC-HESI-MS metodology was used. A decrease in 3,4-DHPEA-EDA (oleacin) and p-HPEA-EDA (oleochantal) was detected whereas, an increase of tyrosol and hydroxytyrosol was measured as a consequence of degradation of ligstroside and oleuropein derivatives. Based on the results it is possible to observe the high nutritional value of the studied oils even after 18 months of conservation.

Evaluation of changes in the quality of extracted oil from olive fruits stored under different temperatures and time intervals.

Chilling and freezing injuries of olives harvested in geographically high elevated locations may affect the quality of olive, and subsequently lead to oil with a poor quality. This study was aiming to investigate the influence of whether changes and freezing condition on the quality of extracted olive oil. The olive Koroneiki cultivar obtained from two origins was stored at three different temperatures (20, 5 and -18 °C) before oil extraction and common analyses (oil yield, acidity, peroxide value, thiobarbitorik acid value, total phenolics level, and color) were carried out in different time intervals (0, 20, 40, and 60 days) in order to assess the olive oil quality. Our data revealed that longer storage times significantly (P < 0.05) decreased the quality of olive oil. The fruits remained at 20 °C provided the lowest oil quality in all parameters. For example, the acidity of olive oil at 20 °C was 177% higher than samples kept at 5 °C after 20 days of olive storage. The general trend for comparing the quality parameters of extracted oils from olives kept at different temperatures was -18 > 5 > 20 °C. No significant negative effect (P < 0.05) was found for the samples kept at -18 °C, compared to 5 °C. Also, the geographical source of olive had a statistically significant influence (P < 0.05) on the quality of olive oil.

A robustness study of calibration models for olive oil classification: Targeted and non-targeted fingerprint approaches based on GC-IMS.

The dual separation in gas chromatography-ion mobility spectrometry generates complex multi-dimensional data, whose interpretation is a challenge. In this work, two chemometric approaches for olive oil classification are compared to get the most robust model over time: i) an non-targeted fingerprinting analysis, in which the overall GC-IMS data was processed and ii) a targeted approach based on peak-region features (markers). A total of 701 olive samples from two harvests (2014-2015 and 2015-2016) were analysed and processed by both approaches. The models built with data samples of 2014-2015 showed that both approaches were suitable for samples classification (success >74%). However, when these models were applied for classifying samples from 2015-2016, better values were obtained using markers. The combination of data from the two harvests to build the chemometric models improved the percentages of success (>90%). These results confirm the potential of GC-IMS based approaches for olive oil classification.

Stimulated Brillouin scattering in combination with visible absorption spectroscopy for authentication of vegetable oils and detection of olive oil adulteration.

Vegetable oils provide high nutritional value in the human diet. Specifically, extra virgin olive oil (EVOO) possesses a higher price than that of other vegetable oils. Adulteration of pure EVOO with other types of vegetable oils has attracted increasing attentions. In this work, a stimulated Brillouin scattering (SBS) combined with visible absorption spectroscopy method is proposed for authentication of vegetable oils and detection of olive oil adulteration. The results provided here have demonstrated that the different vegetable oils and adulteration oils exhibit significant differences in normalized absorbance values of two relevant wavelengths (455 and 670 nm) and frequency shifts of SBS. The normalized absorbance values of all spectra at the two relevant wavelengths of 670 nm and 455 nm linearly decrease with the increase of the adulteration concentration. The Brillouin frequency shifts exponentially increase with the increase of the adulteration concentration. Due to non-destructive and requiring no sample pretreatment procedure, this method can be effectively employed for authentication and detection of oils adulteration.

Validation of Fluorescence Spectroscopy to Detect Adulteration of Edible Oil in Extra Virgin Olive Oil (EVOO) by Applying Chemometrics.

Due to high price and nutritional values of extra virgin olive oil (EVOO), it is vulnerable to adulteration internationally. Refined oil or other vegetable oils are commonly blended with EVOO and to unmask such fraud, quick, and reliable technique needs to be standardized and developed. Therefore, in this study, adulteration of edible oil (sunflower oil) is made with pure EVOO and analyzed using fluorescence spectroscopy (excitation wavelength at 350 nm) in conjunction with principal component analysis (PCA) and partial least squares (PLS) regression. Fluorescent spectra contain fingerprints of chlorophyll and carotenoids that are characteristics of EVOO and differentiated it from sunflower oil. A broad intense hump corresponding to conjugated hydroperoxides is seen in sunflower oil in the range of 441-489 nm with the maximum at 469 nm whereas pure EVOO has low intensity doublet peaks in this region at 441 nm and 469 nm. Visible changes in spectra are observed in adulterated EVOO by increasing the concentration of sunflower oil, with an increase in doublet peak and correspondingly decrease in chlorophyll peak intensity. Principal component analysis showed a distinct clustering of adulterated samples of different concentrations. Subsequently, the PLS regression model was best fitted over the complete data set on the basis of coefficient of determination (R2), standard error of calibration (SEC), and standard error of prediction (SEP) of values 0.99, 0.617, and 0.623 respectively. In addition to adulterant, test samples and imported commercial brands of EVOO were also used for prediction and validation of the models. Fluorescence spectroscopy combined with chemometrics showed its robustness to identify and quantify the specified adulterant in pure EVOO.

Multivariate approaches for stability control of the olive oil reference materials for sensory analysis - part I: framework and fundamentals.

BACKGROUND: Virgin olive oil is the only food product for which sensory analysis is regulated to classify it in different quality categories. To harmonize the results of the sensorial method, the use of standards or reference materials is crucial. The stability of sensory reference materials is required to enable their suitable control, aiming to confirm that their specific target values are maintained on an ongoing basis. Currently, such stability is monitored by means of sensory analysis and the sensory panels are in the paradoxical situation of controlling the standards that are devoted to controlling the panels. RESULTS: In the present study, several approaches based on similarity analysis are exploited. For each approach, the specific methodology to build a proper multivariate control chart to monitor the stability of the sensory properties is explained and discussed. CONCLUSION: The normalized Euclidean and Mahalanobis distances, the so-called nearness and hardiness indices respectively, have been defined as new similarity indices to range the values from 0 to 1. Also, the squared mean from Hotelling's T2 -statistic and Q2 -statistic has been proposed as another similarity index. © 2018 Society of Chemical Industry.

Applying high-resolution melting (HRM) technology to olive oil and wine authenticity.

Olive oil and wine production have a worldwide economic impact. Their market reliability is under great concern because of the increasing number of fraud and adulteration attempts. The need for a traceability system in all its extension is crucial particularly for the cases of olive oils and wines with certified labels, in which only a limited number of olives and grapevine varieties, respectively, are allowed in a restricted well-defined geographical area. Molecular markers have been vastly applied to the food sector, and in particular High-Resolution DNA Melting technology has been successfully applied for olive oil and wine authentication, as part of the traceability system. In this review, the applications of HRM and their usefulness for this sector considering, Safety, Security and Authenticity will be reviewed. A broad overview of the HRM technique will be presented, focusing on the aspects that are crucial for its success, in particular the new generation of fluorescent dsDNA dyes used for amplicon detection and quantification, and the data analysis. A brief outlook on the olive oil and wine authenticity procedures, based on new DNA technology advances, and in which way this may influence the future establishment of a traceability system will be discussed.

Protected Designation of Origin (PDO), Protected Geographical Indication (PGI) and Traditional Speciality Guaranteed (TSG): A bibiliometric analysis.

Despite the importance of the literature on food quality labels in the European Union (PDO, PGI and TSG), our search did not find any review joining the various research topics on this subject. This study aims therefore to consolidate the state of academic research in this field, and so the methodological option was to elaborate a bibliometric analysis resorting to the term co-occurrence technique. Analysis was made of 501 articles on the ISI Web of Science database, covering publications up to 2016. The results of the bibliometric analysis allowed identification of four clusters: "Protected Geographical Indication", "Certification of Olive Oil and Cultivars", "Certification of Cheese and Milk" and "Certification and Chemical Composition". Unlike the other clusters, where the PDO label predominates, the "Protected Geographical Indication" cluster covers the study of PGI products, highlighting analysis of consumer behaviour in relation to this type of product. The focus of studies in the "Certification of Olive Oil and Cultivars" cluster and the "Certification of Cheese and Milk" cluster is the development of authentication methods for certified traditional products. In the "Certification and Chemical Composition" cluster, standing out is analysis of the profiles of fatty acids present in this type of product.

Olive Oil-related Anti-inflammatory Effects on Atherosclerosis: Potential Clinical Implications.

BACKGROUND AND OBJECTIVE: Atherosclerosis is characterized by a chronic low-grade inflammatory process which can result in atherothrombosis and a number of cardiovascular diseases (CVD). It is believed to be caused by multiple processes that involve inflammation and immunity. Mediterranean Diet (MedD) has been discovered to possess anti-inflammatory properties and associated with a reduction in the CVD risk and mortality. Its main component, extra-virgin olive oil (EVOO), is believed to be largely responsible for these effects and therefore, has been investigated in various studies. The present review article aims to summarize the available literature on the antiinflammatory and cardio-protective effects of EVOO. METHODS: A search based on the key concepts "olive oil", "atherosclerosis", "inflammation" and "cardiovascular disease" was performed to retrieve relevant studies and articles on the association between the consumption of EVOO and the levels of inflammatory biomarkers as well as CVD incidence and mortality from online databases; Pubmed, Embase and Cochrane Library. RESULTS: Consumption of EVOO is associated with a reduction in inflammatory biomarkers and molecules implicated in atherosclerosis as well as CVD incidence and mortality as well as other complications such as heart failure and atrial fibrillation. Moreover, these anti-inflammatory and cardioprotective effects of EVOO are mostly attributable to its high content of polyphenol molecules. CONCLUSION: Currently available evidence supports the anti-inflammatory and cardio-protective roles of EVOO. However, there is limited amount of available randomized controlled trials especially lacking those investigating the use of EVOO as secondary prevention, heterogeneity of study design, limited generalization to wide population groups, and inability to determine the minimum intake of EVOO required to clinically achieve the anti-inflammatory and cardioprotective effects. Therefore, more highquality randomized controlled trials still need to be carried out to overcome these challenges to further assess the health benefits of EVOO consumption and potentially translate it into clinical practice as primary or secondary prevention of atherosclerosis-related conditions.

Effect of Extra Virgin Olive Oil and Table Olives on the ImmuneInflammatory Responses: Potential Clinical Applications.

BACKGROUND AND OBJECTIVE: Extra virgin olive oil (EVOO) is the common element among the Mediterranean countries. It can be considered a nutraceutical and functional food, thanks to its bioactive compounds. It can act and modulate different processes linked to ageing and age-related diseases related to a common chronic low grade inflammation. Depending on the cultivar, the growth conditions, the period of harvesting, the productive process and time of product storage, EVOO could contain different amount of vegetal components. Of course, the same is for table olives. METHODS: The aim of our review is to summarize the effects of EVOO and table olives on the immunemediated inflammatory response, focusing our attention on human studies. RESULTS: Our report highlights the effect of specific molecules obtained from EVOO on the modulation of specific cytokines and anti-oxidants suggesting the importance of the daily consumption of both EVOO and table olives in the context of a Mediterranean dietary pattern. In addition, the different action on immune-inflammatory biomarkers, are depending on the olive tree cultivar. CONCLUSION: Thanks to their bioactive compounds, EVOO and table olive can be considered as nutraceutical and functional foods. The beneficial effects analysed in this review will help to understand the potential application of specific olive components as therapeutic adjuvant, supplements or drugs.

Extra Virgin Olive Oil and Cardiovascular Diseases: Benefits for Human Health.

BACKGROUND AND OBJECTIVE: The cardioprotective properties of Mediterranean Diet were demonstrated for the first time from the Seven Country Study. In the last few decades, numerous epidemiological studies, as well as intervention trial, confirmed this observation, pointing out the close relationship between the Mediterranean diet and cardiovascular diseases. In this context, extra virgin olive oil (EVOO), the most representative component of this diet, seems to be relevant in lowering the incidence of cardiovascular events, including myocardial infarction and stroke. From a chemical point of view, 98-99% of the total weight of EVOO is represented by fatty acids, especially monounsaturated fatty acids such as oleic acid. Tocopherols, polyphenols and other minor constituents represent the remaining 1-2%. All these components may potentially contribute to "health maintenance" with their beneficial effects by EVOOO. METHODS: Studies that examined the effect of EVOO supplementation in healthy subjects and in individuals at cardiovascular risk were included. CONCLUSION: The studies analyzed demonstrated the role of EVOO as anti-inflammatory, antioxidant and vasodilatory nutrient that may contribute to lower the atherosclerotic burden.

Liver Protective Effects of Extra Virgin Olive Oil: Interaction between Its Chemical Composition and the Cell-signaling Pathways Involved in Protection.

BACKGROUND AND OBJECTIVE: The liver is an organ susceptible to a multitude of injuries that causes liver damage, like steatosis, non-alcoholic steatohepatitis, cirrhosis, hepatocellular carcinoma, and ischemia-reperfusion injury. Extra virgin olive oil (EVOO), presents several protective effects on the liver, reducing hepatic steatosis, hepatocyte ballooning, fibrogenesis, preventing lipid peroxidation, among other effects. Due to its high levels of monounsaturated fatty acids, mainly oleic acid and phenolic compounds, such as hydroxytyrosol and oleuropein, EVOO is able to participate in the activation of different signaling pathways in the hepatocytes involved in the prevention of inflammation, oxidative stress, endoplasmic reticulum stress, mitochondrial dysfunction, and insulin resistance, allowing the prevention or resolution of liver damage. The aim of this work is to offer an update of the molecular effects of EVOO in the liver and its protective properties to prevent the establishment of liver damage through the regulation of different cell-signaling pathways. METHODS: Searches that considered the effects of EVOO in in vivo and in vitro models, whith emphasis in the molecular mechanism of liver tissue damage and prevention and/or treatment of steatosis, steatohepatitis, cirrhosis, hepatocellular carcinoma, and ischemia-reperfusion injury. CONCLUSION: The most relevant molecular effects of EVOO involved in the prevention or resolution of liver damage are: (i) Activation of the nuclear transcription factor erythroid-derived 2-like 2 (Nfr2), inducing the cellular antioxidant response; (ii) Inactivation of the nuclear transcription factor-κB (NF- κB), preventing the cellular inflammatory response; and (iii) Inhibition of the PERK pathway, preventing endoplasmic reticulum stress, autophagy, and lipogenic response.

The Protective Effects of Extra Virgin Olive Oil on Immune-mediated Inflammatory Responses.

BACKGROUND AND OBJECTIVE: The increasing interest in the Mediterranean diet (MeDiet) hinges on the relevant role it plays in inflammatory diseases. Several clinical, epidemiological and experimental evidences suggest that consumption of the MeDiet reduces the incidence of certain pathologies related to oxidative stress, chronic inflammation and immune system diseases such as cancer, atherosclerosis and cardiovascular disease (CVD). These reductions can be partially attributed to extra virgin olive oil (EVOO) consumption which has been described as a key bioactive food because of its high nutritional quality and its particular composition of fatty acids, vitamins and polyphenols. Indeed, the beneficial effects of EVOO have been linked to its fatty acid composition, which is very rich in monounsaturated fatty acids (MUFA), and has moderate saturated and polyunsaturated fatty acids (PUFA). The current knowledge available on the beneficial effects of EVOO and its phenolic compounds, specifically its biological properties and antioxidant capacity against immune-mediated inflammatory responses (atherosclerosis, rheumatoid arthritis, diabetes, obesity, cancer, inflammatory bowel disease or neurodegenerative disease, among others) in addition to its potential clinical applications. CONCLUSION: The increasing body of studies carried out provides compelling evidence that olive polyphenols are potential candidates to combat chronic inflammatory states.