Discrimination of botanical origin of olive oil from selected Greek cultivars by SPME-GC-MS and ATR-FTIR spectroscopy combined with chemometrics.

BACKGROUND: Consumers today wish to know the botanical origin of the olive oil they purchase. The objective of the present study was the development of robust chemometric models based on gas chromatography-mass spectrometry (GC-MS) and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) for the purpose of botanical differentiation of three commercial Greek olive oil cultivars. RESULTS: Using the solid-phase microextraction technique (SPME), volatile compounds (VC) were obtained and analyzed by GC-MS. Five hydrocarbons and one ester were selected by the forward stepwise algorithm, which best discriminated the olive oil samples. From ATR-FTIR analysis, the spectral regions chosen from the forward stepwise algorithm were associated with CO stretching vibration of the esters of triglycerides and the CH bending vibrations of the CH2 aliphatic group and double bonds. Application of the supervised methods of linear and quadratic discriminant cross-validation analysis, based on VC data, provided a correct classification score of 97.4% and 100.0%, respectively. Corresponding statistical analyses were used in the mid-infrared spectra, by which 96.1% of samples were discriminated correctly. CONCLUSION: ATR-FTIR and SPME-GC-MS techniques in conjunction with the appropriate feature selection algorithm and classification methods proved to be powerful tools for the authentication of Greek olive oil. The proposed methodology could be used in an industrial setting for determination of the botanical origin of Greek olive oil. © 2020 Society of Chemical Industry.

Preliminary study on the potential application of Fourier-transform mid-infrared for the evaluation of overall quality and authenticity of Moroccan virgin olive oil.

BACKGROUND: Olive oil provides a wide range of health-promoting compounds. The quality of olive oil is an even more complex concept as it is affected by several factors, such as variety, season, stage of maturation, extraction processing, and so on. The main objective of this study was to determine the potential of chemical and mid-infrared spectroscopy techniques to determine the quality and authenticity of virgin olive oil (VOO). For this, we studied 41 VOOs originating from five regions of Morocco (Fez/Meknes, Eastern, Northern, Beni-Mellal/Khenifra, and Marrakech/Safi) and produced using different agricultural and technological conditions during two successive crop seasons (2015-2016 and 2016-2017). RESULTS: By applying principal component analysis and factorial discriminant analysis with leave-one-out validation to the mid-infrared spectroscopy, clear discrimination between VOO samples according to their geographic origin and variety was observed, with correct classification rates of 91.87% and 91.87% being observed respectively. The application of partial least-squares regression to mid-infrared and chemical data sets allowed excellent prediction of free acidity, peroxide value, k270 , and chlorophyll level with R2 of 0.99, 0.97, 0.98, and 0.93 respectively, and good prediction of k232 (R2 = 0.84). CONCLUSION: The results demonstrate that mid-infrared spectroscopy coupled with chemometric tools could be used as a rapid screening tool for evaluating the overall quality and authenticity of VOO. © 2020 Society of Chemical Industry.

Fresh and Aromatic Virgin Olive Oil Obtained from Arbequina, Koroneiki, and Arbosana Cultivars.

Three factors for the extraction of extra virgin olive oil (EVOO) were evaluated: diameter of the grid holes of the hammer-crusher, malaxation temperature, and malaxation time. A Box-Behnken design was used to obtain a total of 289 olive oil samples. Twelve responses were analyzed and 204 mathematical models were obtained. Olives from super-intensive rainfed or irrigated crops of the Arbequina, Koroneiki, and Arbosana cultivars at different stages of ripening were used. Malaxation temperature was found to be the factor with the most influence on the total content of lipoxygenase pathway volatile compounds; as the temperature increased, the content of volatile compounds decreased. On the contrary, pigments increased when the malaxation temperature was increased. EVOO from irrigated crops and from the Arbequina cultivar had the highest content of volatile compounds. Olive samples with a lower ripening degree, from the Koroneiki cultivar and from rainfed crops, had the highest content of pigments.

Study of the minor fraction of virgin olive oil by a multi-class GC-MS approach: Comprehensive quantitative characterization and varietal discrimination potential.

For the first time, a multi-class GC-MS method was applied to perform the quantitative-profiling of the minor fraction of VOOs (considering >40 compounds) in a single run. This comprehensive methodology has demonstrated a remarkable profiling ability on five groups of compounds (phenolic and triterpenic compounds, tocopherols, sterols and free fatty acids) with wide range of polarities/volatilities and chemical entities. After the complete analytical validation of the method, 32 VOO samples from eight different cultivars (some of them very scarcely studied before) were analyzed and the quantitative results were subjected to both non-supervised and supervised multivariate statistics for testing the capability of the determined VOO minor compounds to discriminate the varietal origin of the samples. Typical compositional profiles were defined for each cultivar and promising potential varietal markers were pointed out. The models built to discriminate Cayon and Maurino samples from the rest exhibited the best quality parameters. The relative levels of tocopherols together with characteristic concentration of luteolin, ß-sitosterol and tyrosol were, for instance, the most specific features of Cayon VOOs.

Headspace Solid-Phase Microextraction-Gas Chromatography-Mass Spectrometry Quantification of the Volatile Profile of More than 1200 Virgin Olive Oils for Supporting the Panel Test in Their Classification: Comparison of Different Chemometric Approaches.

A reliable and robust tool for supporting the panel test in virgin olive oil classification is still required. We propose four chemometric approaches based on t test, principal component analysis (PCA) and linear discriminant analysis (LDA), applied for combining sensorial data, and chemical measurements. The former was from the panel test, and the latter was from headspace solid-phase microextraction-gas chromatography-mass spectrometry quantitation of 73 volatile organic compounds (VOCs) of 1223 typical commercial virgin olive oils, with most of them recognized as difficult to classify with accuracy by the panel test. The approaches were developed and validated, and the best results, with 83.5% correct classification, were using the PCA-LDA approach. Among the other methods, developed for proposing simplified procedures based on a smaller number of VOCs, the best method gave 80.1% correct classification only using 10 VOCs. All of the approaches suggested that octane, heptanal, pent-1-en-3-ol, Z-3-hexenal, nonanal, and 4-ethylphenol should be considered as a basis of volatiles for classification of olive oil samples.

Authentication of the geographical origin of extra-virgin olive oil of the Arbequina cultivar by chromatographic fingerprinting and chemometrics.

This paper proposes to use chromatographic fingerprints coupled to multivariate techniques to authenticate the geographical origin of extra-virgin olive oils (EVOO) of the Arbequina botanical variety. This methodology uses the whole or part of the chromatogram as input data for the classification models but does not identify or quantify the chemicals constituents. Arbequina monovarietal EVOOs from three geographical origins were studied: two from adjacent European Protected Designation of Origin areas, Siurana and Les Garrigues, in Catalonia in the northeast of Spain; and the third from the south of Spain (Andalucia and Murcia). Three chromatographic fingerprints of each sample were obtained by both reverse and normal phase liquid chromatography coupled to charged aerosol detector (HPLC-CAD), and high temperature gas chromatography coupled to flame ionization detector [(HT)GC-FID]. Principal component analysis (PCA) was used as exploratory technique and soft independent modelling of class analogy (SIMCA) and partial least square-discriminant analysis (PLS-DA) were used as classification methods. High and low-level data fusion strategies were also applied to improve the classification results obtained when the data acquired from each analytical technique were separately used. The results were best for the PLS-DA model with low-level fusion of two techniques (HT)GC-FID with HPLC-CAD, independently of the phase mode. Sensitivity and specificity were 100% in almost all classes, error was 0% for all classes and an inconclusive ratio of just 4% was obtained for the Les Garrigues class due to double assignations.

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.

Combined targeted and untargeted profiling of volatile aroma compounds with comprehensive two-dimensional gas chromatography for differentiation of virgin olive oils according to variety and geographical origin.

Comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC × GC-TOF-MS) was combined with conventional mono-dimensional GC-MS to differentiate Croatian virgin olive oils (VOO) according to variety and geographical origin, based on the profile of volatile aroma compounds isolated by HS-SPME. More than 1000 compounds were detected after untargeted profiling and 256 were identified or tentatively identified, providing one of the most detailed profiles of volatile aroma compounds in VOO up to date. Among them, 131 volatile compounds were significantly different across monovarietal VOOs, while 60 were found useful for the discrimination according to geographical origin. Many major lipoxygenase and minor non-lipoxygenase-generated compounds were shown to have discriminating ability with respect to both factors. Multivariate statistical analysis extracted twenty-one volatile markers with the highest discriminant power for varietal differentiation. The approach reported may have practical application in better understanding, defining, managing, and communicating the varietal or geographical typicity of monovarietal VOOs.

Anticancer activity modulation of an innovative solid formulation of extra virgin olive oil by cultured zeolite scaffolds.

This paper deals with the design and manufacture of pure and hybrid synthetic (Mixed Matrix Membranes, MMMs) zeolite scaffolds (containing various amount of zeolite crystals dispersed in a polymeric matrix) to obtain new biomaterials. These scaffolds can potentially be used in the field of translational medicine to obtain innovative results to address tumorigenesis mechanisms with the promotion of an effort to deal with technical methods and information. Since olive oil has beneficial effects in healthy human cells and slows down and/or inhibits cell growth, the aim of this work was to monitor the protective and beneficial antitumor effects of olive oil in a new solid formulation (Spread Bio-Oil) on cancer cell cultured on zeolite scaffolds. In order to investigate the cytotoxicity of the new bio-oil spread and to test antiproliferative activity on the cancer cells we used two phenotypically different human breast cancer cell lines (MCF-7 and MDA-MB-231) seeded on various morphologies of zeolite membranes. We report the fabrication and characterization of pure and hybrid (MMMs) zeolite membranes and evaluated the intensively cell adhesion, spreading and cell growth by adhesion test, MTT, optical microscopy analyses and Scanning Electronic Microscopy (SEM) microphotography analyses. Our results demonstrate that both cell lines adhered and grow on all zeolite surfaces and that both show better viability after Spread Bio-Oil treatments. All cell adhesions are a specific membrane-type and, in particular, MCF-7 cells interact and adhere preferentially on pure zeolite membranes. Cancer cells seem to recognize and prefer the characteristics of the supports according to the following trend: Co-ZSM-5 > Co-S-1 > 13X. Moreover, Co-ZSM-5 zeolite membranes were the best scaffolds and MDA-MB-231 cells after administration of Spread Bio-Oil showed less viability with respect to MCF-7 responding better to all concentrations of the innovative food. Our data indicate that Spread Bio-Oil decreases at very low concentration values (5, 10, 25, 50, 100, 200 and 300 µg/mL) cell proliferation in a dose- and time-dependent manner. The work confirms both the superiority of pure zeolite scaffolds for cultures of human normal and cancer cells and Spread Bio-Oil as an innovative food preserving all the beneficial and healthy properties of the extra virgin olive oil from which it derives.

Towards understanding the varietal typicity of virgin olive oil by correlating sensory and compositional analysis data: a case study.

To investigate if the anecdotal varietal typicity concepts for two monovarietal virgin olive oils (VOO) can be scientifically supported and explained, VOO samples were sorted according to typicity grade and related to sensory and compositional data for volatiles and phenols. Clear inter-varietal, as well as intra-varietal boundaries between more and less typical samples were established by univariate and multivariate statistics. A variety-typical complex odor was related to a complex VOO volatile composition with relatively high amounts of lipoxygenase-derived compounds, accompanied by hydrocarbons, terpenes, and benzenoids. A simpler odor, described mostly as green and typical for the other monovarietal VOO, coincided with the lower amounts of the same volatiles. The intensity of bitterness and pungency was mostly in correlation with the amount of major phenols. Two monovarietal VOOs were clearly distinguished with respect to their variety-typical expression of pungency: the one described as gradually increasing was tentatively related to pinoresinol, while the other, described as immediately strong and burning, was assumed to originate mainly from p-HPEA-EDA. Intra-varietal typicity grades correlated with hedonic liking, as well as with general VOO positive sensory attributes related to key volatiles and phenols.

Gas Chromatography-Mass Spectrometry-Olfactometry To Control the Aroma Fingerprint of Extra Virgin Olive Oil from Three Tunisian Cultivars at Three Harvest Times.

Gas chromatography-mass spectrometry-olfactometry was used for the analysis of volatile compounds and key odorants of three less studied Tunisian olive oil cultivars for the first time. A total of 42 aroma compounds were identified and quantified in extra virgin olive oils. The present study revealed that the most dominant volatiles in olive oil samples qualitatively and quantitatively were aldehydes and alcohols, followed by terpenes and esters. Indeed, chemometric analysis has shown a correlation between chemical compounds and sensory properties. The determination of aroma-active compounds of olive oil samples was carried out using aroma extract dilution analysis. A total of 15 aroma-active compounds were detected in the aromatic extract of extra virgin olive oil, of which 14 were identified. On the basis of the flavor dilution (FD) factor, the most potent aromatic active compound was hexanal (FD = 512) in Fakhari olive oil, (FD = 256) in Touffehi oils, and (FD = 128) in Jemri olive oil.

Chemical and sensory differences between high price and low price extra virgin olive oils.

The aim of the study was to identify new potential chemical markers of extra virgin olive oil (EVOO) quality by using a multicomponent analysis approach. Sixty-six EVOOs were purchased from the Italian market and classified according to their price as low price EVOOs (LEVOOs) and high price EVOOs (HEVOOs) costing 3.60-5.90euro/L and 7.49-29.80euro/L respectively. Sensory and chemical parameters strictly related to olive oil quality have been investigated, like volatile substances, polar phenolic substances, antioxidant activity, fatty acid composition, and α-tocopherol. Significant differences in terms of chemical composition and sensory features have been highlighted between the two EVOOs classes investigated, proving a generally lower level of quality of LEVOOs, clearly showed also by means of principal component analysis. Among the most interesting outcomes, R ratio (free tyrosol and hydroxytyrosol over total free and bound forms), measuring the extent of secoiridoids hydrolysis, resulted to be significantly higher in LEVOOs than in HEVOOs. Other key differences were found in the volatile substances composition, in the stearic acid percentage and in p-coumaric acid content.

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.

Resolution-optimized headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) for non-targeted olive oil profiling.

A prototype gas chromatography-ion mobility spectrometry (GC-IMS) system, hyphenating temperature-ramped headspace GC to a modified drift time IMS cell, was evaluated and compared to a conventional, isothermal capillary column (CC)-IMS system on the example of the geographical differentiation of extra virgin olive oils (EVOO) from Spain and Italy. It allows orthogonal, 2D separation of complex samples and individual detection of compounds in robust and compact benchtop systems. The information from the high-resolution 3D fingerprints of volatile organic compound (VOC) fractions of EVOO samples were extracted by specifically developed chemometric MATLAB® routines to differentiate between the different olive oil provenances. A combination of unsupervised principal component analysis (PCA) with two supervised procedures, linear discriminant analysis (LDA) and k-nearest neighbors (kNN), was applied to the experimental data. The results showed very good discrimination between oils of different geographical origins, featuring 98 and 92% overall correct classification rate for PCA-LDA and kNN classifier, respectively. Furthermore, the results showed that the higher resolved 3D fingerprints obtained from the GC-IMS system provide superior resolving power for non-targeted profiling of VOC fractions from highly complex samples such as olive oil. Graphical abstract Principle of the determination of geographic origins of olive oils by chemometric analysis of three-dimensional HS-GC-IMS fingerprints.

Optical Spectroscopic Analysis for the Discrimination of Extra-Virgin Olive Oil.

We demonstrate the ability to discriminate between five brands of commercially available extra-virgin olive oil (EVOO) using Raman spectroscopy or fluorescence spectroscopy. Data was taken on both a 'bulk optics' free space system and on a compact handheld device, each capable of taking both Raman and fluorescence data. With the compact Raman device we achieved an average sensitivity and specificity of 98.4% and 99.6% for discrimination, respectively. Our approach illustrates that both Raman and fluorescence spectroscopy can be used for portable discrimination of EVOOs. This technique may enable detection of EVOO that has undergone counterfeiting or adulteration. The main challenge with this technique is that oxidation of EVOO causes a shift in the Raman signal over time. It would therefore be necessary to retrain the database regularly. We demonstrate preliminary data to address this issue, which may enable successful discrimination over time. We show that by discarding the first principal component, which contains information on the variations due to oxidation, we can improve discrimination efficiency.

Extra virgin olive oil: a key functional food for prevention of immune-inflammatory diseases.

Nowadays, it is clear that an unhealthy diet is one of the prime factors that contributes to the rise of inflammatory diseases and autoimmunity in the populations of both developed and developing countries. The Mediterranean diet has been associated with a reduced incidence of certain pathologies related to chronic inflammation and the immune system. Olive oil, the principal source of dietary lipids of the Mediterranean diet, possesses a high nutritional quality and a particular composition, which is especially relevant in the case of Extra Virgin Olive Oil (EVOO). EVOO is obtained from olives solely by mechanical or other physical preparation methods, under conditions that do not alter the natural composition. EVOO is described as a key bioactive food with multiple beneficial properties and it may be effective in the management of some immune-inflammatory diseases. In this review, the key research is summarised which provides evidence of the beneficial effects of EVOO and its minor components focusing on their mechanisms on immune-inflammatory diseases such as rheumatoid arthritis, systemic lupus erythematosus, inflammatory bowel disease and sclerosis.

Olive oil sensory defects classification with data fusion of instrumental techniques and multivariate analysis (PLS-DA).

Three instrumental techniques, headspace-mass spectrometry (HS-MS), mid-infrared spectroscopy (MIR) and UV-visible spectrophotometry (UV-vis), have been combined to classify virgin olive oil samples based on the presence or absence of sensory defects. The reference sensory values were provided by an official taste panel. Different data fusion strategies were studied to improve the discrimination capability compared to using each instrumental technique individually. A general model was applied to discriminate high-quality non-defective olive oils (extra-virgin) and the lowest-quality olive oils considered non-edible (lampante). A specific identification of key off-flavours, such as musty, winey, fusty and rancid, was also studied. The data fusion of the three techniques improved the classification results in most of the cases. Low-level data fusion was the best strategy to discriminate musty, winey and fusty defects, using HS-MS, MIR and UV-vis, and the rancid defect using only HS-MS and MIR. The mid-level data fusion approach using partial least squares-discriminant analysis (PLS-DA) scores was found to be the best strategy for defective vs non-defective and edible vs non-edible oil discrimination. However, the data fusion did not sufficiently improve the results obtained by a single technique (HS-MS) to classify non-defective classes. These results indicate that instrumental data fusion can be useful for the identification of sensory defects in virgin olive oils.

OGDD (Olive Genetic Diversity Database): a microsatellite markers' genotypes database of worldwide olive trees for cultivar identification and virgin olive oil traceability.

Olive (Olea europaea), whose importance is mainly due to nutritional and health features, is one of the most economically significant oil-producing trees in the Mediterranean region. Unfortunately, the increasing market demand towards virgin olive oil could often result in its adulteration with less expensive oils, which is a serious problem for the public and quality control evaluators of virgin olive oil. Therefore, to avoid frauds, olive cultivar identification and virgin olive oil authentication have become a major issue for the producers and consumers of quality control in the olive chain. Presently, genetic traceability using SSR is the cost effective and powerful marker technique that can be employed to resolve such problems. However, to identify an unknown monovarietal virgin olive oil cultivar, a reference system has become necessary. Thus, an Olive Genetic Diversity Database (OGDD) (http://www.bioinfo-cbs.org/ogdd/) is presented in this work. It is a genetic, morphologic and chemical database of worldwide olive tree and oil having a double function. In fact, besides being a reference system generated for the identification of unkown olive or virgin olive oil cultivars based on their microsatellite allele size(s), it provides users additional morphological and chemical information for each identified cultivar. Currently, OGDD is designed to enable users to easily retrieve and visualize biologically important information (SSR markers, and olive tree and oil characteristics of about 200 cultivars worldwide) using a set of efficient query interfaces and analysis tools. It can be accessed through a web service from any modern programming language using a simple hypertext transfer protocol call. The web site is implemented in java, JavaScript, PHP, HTML and Apache with all major browsers supported. Database URL: http://www.bioinfo-cbs.org/ogdd/.

Oil quality parameters and quantitative measurement of major secoiridoid derivatives in Neb Jmel olive oil from various Tunisian origins using qNMR.

BACKGROUND: Olive oil contains compounds with interesting biological activities which are influenced by the cultivar, the geographic origin and other factors. The aims of this work were to (1) investigate these factors in Neb Jmel olive oil from various Tunisian origins; (2) determine the influence of geographic conditions on phenolic composition of Neb Jmel olive oil and consequently on the antioxidant compounds; and (3) verify whether oils could be discriminated based on geographical origin. RESULTS: The characterisation of extra-virgin Neb Jmel olive oil produced in its original location has been conducted. Owing to the effect of the genotype and environmental, agronomic and technological factors on the chemical composition of olive oil and its quality, all studied olives were collected at the same season, and their oil obtained under the same processing technique. Many analyses were carried out to characterise the different olive oils: free acidity, peroxide value, fatty acid composition, Rancimat assay, pigments content and phenolic compounds by (1) H NMR. A recently developed method for the direct measurement of the oleocanthal and oleacein levels in olive oil by quantitative (1) H NMR was applied. The method was applied to the study of four Neb Jmel olive oils samples, and a broad variation of concentrations of all four secoiridoids was recorded. The concentration of each ranged from 55 to 529 mg kg(-1) and the sum of the four major secoiridoids (known as D3) ranged from 436 to 1063 mg kg(-1) . CONCLUSION: The quantification of major phenolic compounds of olive oil by NMR indicated that environmental conditions influence the production of qualitative phenolic fractions. All these compounds can be used as base 'markers' to characterise and differentiate these olive oil on geographic origin. © 2016 Society of Chemical Industry.