Improved liquid chromatography tandem mass spectrometry method for the determination of phenolic compounds in virgin olive oil

Chromatographic fingerprinting of epiphytic fungal strains isolated from Withania somnifera and biological evaluation of isolated okaramine H

Medicinal plants are "goldmines" of natural products, and continue to provide key scaffolds for drug development. They have immense therapeutic potential, encapsulating a plethora of metabolites within them, which have yet to be explored. Withania somnifera (L.) Dunal is one such medicinal plant known since time immemorial for its therapeutic activity in the Ayurveda system of medicine. Studies have revealed Nature's marvel of these medicinal plants harbouring endophytic and epiphytic microorganisms from phyllosphere to rhizosphere. Chromatographic fingerprinting was carried out using HPTLC and HPLC on five epiphytic strains isolated from the leaves, stem and fruits of Withania somnifera. Out of five filamentous fungi, one fungus identified as Aspergillus aculeatus S20 was well explored. An indole alkaloid, okaramine H, was isolated using systematic chromatographic investigation at a retention time of 26.278 min showing λmax at 206, 236, 284 and 370 nm. Confirmation was achieved using NMR and mass spectrometry (MS) as analytical techniques. Structure elucidation was done by studying the fragmentation pattern using MS/MS and an accurate mass was determined using HR-ESI-QTOF-MS showing m/z of 521.2546 [M + H]+. The percentage purity of isolated okaramine H was found to be >90. Well known for its insecticidal activity, okaramine H was explored for its antileishmanial activity against the Leishmania donovani parasite for the first time. Under in vitro conditions, the compound showed an inhibitory effect on Leishmania donovani promastigotes with an IC50 of 147 μg mL-1.

Bioactive compounds in Spanish extra virgin olive oils: Migration and stability according to the culinary technique used

Extra virgin olive oil (EVOO) is a basic food of the Mediterranean diet and an important source of bioactive compounds, especially phenolic substances. The culinary techniques to which the oil is subjected before consumption cause the migration of these compounds, hence the importance of studying their stability before and after culinary treatment. We determined the behaviour of the phenols present in EVOO and its total antioxidant capacity before and after the use of various culinary techniques such as deep frying, boiling (in a water/oil mixture (W/O) and sauteing, observing that the study parameters varied according to the variety of oil and the culinary technique used. Significant statistical differences were observed between the different varieties of EVOO according to the culinary technique used. But this was not the case with respect to polyphenol content, for which no statistically significant differences were observed among the different varieties of EVOO according to the culinary techniques employed (p > 0.05), except with the Arbequina variety (p < 0.05). With respect to the individual polyphenols - tyrosol, p-vainillin, vanillic acid, gallic acid, trans-caffeic acid, ferulic acid and luteolin - our analysis shows that although there were differences in content between raw EVOO and EVOO treated with each of the culinary techniques, these differences were not statistically significant (p > 0.05). There were significant losses of oleocanthal with the W/O boiling technique, but content increases were observed following sauteing and deep frying with respect to raw EVOO. Total antioxidant capacity presented a similar pattern in all samples, with increases after sauteing and decreases after W/O boiling and deep frying. ABTS was the most suitable technique for determining antioxidant capacity in EVOO. In short, the behaviour of the bioactive compounds in EVOO depends on the temperature and the cooking medium used.

Classification and Antioxidant Activity Evaluation of Edible Oils by Using Nanomaterial-Based Electrochemical Sensors

The classification of olive oils and the authentication of their biological or geographic origin are important issues for public health and for the olive oil market and related industries. The development of techniques for olive oil classification that are fast, easy to use, and suitable for online, in situ and remote operation is of high interest. In this study, the possibility of discriminating and classifying vegetable oils according to different criteria related to biological or geographical origin was assessed using cyclic voltammograms (CVs) as input data, obtained with electrochemical sensors based on carbonaceous nanomaterials and gold nanoparticles. In this context, 44 vegetable oil samples of different categories were analyzed and the capacity of the sensor array coupled with multivariate analysis was evaluated. The characteristics highlighted in voltammograms are related to the redox properties of the electroactive compounds, mainly phenolics, existing in the oils. Moreover, the antioxidant activity of the oils' hydrophilic fraction was also estimated by conventional spectrophotometric methods (1,1-diphenyl-2-picrylhydrazyl (DPPH) and galvinoxyl) and correlated with the voltammetric responses of the sensors. The percentage of DPPH and galvinoxyl inhibition was accurately predicted from the voltammetric data, with a correlation coefficients greater than 0.97 both in calibration and in validation. The results indicate that this method allows for a clear discrimination of oils from different biological or geographic origins.

Hydroxytyrosol in Foods: Analysis, Food Sources, EU Dietary Intake, and Potential Uses

Hydroxytyrosol (HT) is a phenolic compound with proven biological properties present in a limited number of foods such as table olives, virgin olive oil (VOO) and wines. The present work aims to evaluate the dietary intake of HT in the European (EU) population by compiling scattered literature data on its concentration in foods. The consumption of the involved foods was estimated based on the EFSA Comprehensive European Food Consumption Database. The updated average contents of HT are as follows: 629.1, 5.2 and 2.1 µg/g for olives, olive oil and wine, respectively. The HT estimated intake in the European Union (EU) adult population falls within 0.13–6.82 mg/day/person, with table olives and wine being the main contributors. The estimated mean dietary intake of HT in EU countries is 1.97 ± 2.62 mg/day. Greece showed the highest HT intake (6.82 mg/day), while Austria presented the lowest (0.13 mg/day). Moreover, HT is an authorized novel food ingredient in the EU that can be added to different foods. Since the estimated HT intake is substantially low, the use of HT as a food ingredient seems feasible. This opens new possibilities for revalorizing waste products from olive oil and olive production which are rich HT sources.

Application of the INFOGEST Standardized Method to Assess the Digestive Stability and Bioaccessibility of Phenolic Compounds from Galician Extra-Virgin Olive Oil

The INFOGEST standardized method was applied to assess the potential bioaccessibility and bioaccessibility of the phenolic compounds from a Galician extra-virgin olive oil (EVOO). The in vitro digestion model involves three steps and generates two fractions after each one: an aqueous fraction (namely, water phase (Wp)) and an oily fraction (namely, oily phase (Op)). The results showed that secoiridoids were the most abundant family in the Galician EVOO polar fraction, representing 98% of the total phenolic compounds. After oral digestion, phenolic acids and simple phenols were mainly detected in Wp, while lignans and flavonoids were mostly found in Op. After gastric digestion, extensive hydrolysis of secoiridoids was observed to generate free tyrosol, hydroxytyrosol, and hydroxytyrosol acetate. The instability of secoiridoids after intestinal digestion was again responsible for the release of simple phenols, which were mainly recovered in Wp together with flavonoids. In contrast, lignans were stable to duodenal conditions and remained in Op.

Total Analysis of the Major Secoiridoids in Extra Virgin Olive Oil: Validation of an UHPLC-ESI-MS/MS Method

Extra virgin olive oil (EVOO), one of the key foods of the Mediterranean diet, is distinguished by its high content of nutritional and antioxidant compounds compared to other vegetable oils. During EVOO production, the major secoiridoids of EVOO, oleacein, oleocanthal, ligstroside, and oleuropein aglycones, undergo a series of transformations to open- and closed-structure forms. The resulting mixture of compounds can become more complex during the analytical procedure, due to the keto-enol tautomerism of the open forms and their interaction with polar solvents, and therefore more challenging to analyze. Employing the same extraction method used to analyze the other EVOO phenolic compounds, we report here a simple UHPLC-ESI-MS/MS procedure for the quantification of those secoiridoids that is able to co-elute the different isomers of each compound. The method was validated following AOAC guidelines, and the matrix effect and recoveries were within satisfactory limits.

Choline chloride-based deep eutectic solvents as potential solvent for extraction of phenolic compounds from olive leaves: Extraction optimization and solvent characterization

This study evaluates the use of deep eutectic solvents (DES) prepared with choline chloride ([Ch]Cl) and carboxylic acids for phenolic compound extraction from olive leaves. These extracts were then compared to those obtained using ethanol. The effects of temperature and water addition during DES- and ethanol-based extractions were analyzed using response surface methodology. Due to the lack of solid-liquid equilibrium (SLE) data for [Ch]Cl + acetic acid, SLE, and DES density and viscosity with and without water addition were measured and analyzed. [Ch]Cl:acetic acid (54.1 °C, 50.0% water addition) extracted 15% more phenolic compounds than ethanol (54.1 °C, 0.5% water addition), according to UHPLC-MS based analyses. SLE analyses showed that [Ch]Cl + acetic acid presented a eutectic region at close to a 1:2 molar ratio. DES precursors and water addition influenced solvent physical properties and phenolic compound yield. DES was confirmed to be an innovative, strong solvent for phenolic compound extraction from olive leaves.

Simultaneous determination of polyphenol content Vitis amurensis Rupr. by tandem mass spectrometry

Vitis amurensis Ruprecht contains a large number of polyphenolic compounds which are biologically active components. For the most efficient and safe extraction supercritical carbon dioxide was used. In this work, for the first time, a comparative metabolomic study of biologically active substances of wild grapes collected from five different places of the Primorsky and Khabarovsk territories is carried out. To identify target analytes in ethanol extracts of grape berries, high performance liquid chromatography (HPLC) was used in combination with an amaZon SL ion trap (manufactured by BRUKER DALTONIKS, Germany) equipped with an ESI electrospray ionization source in negative and positive ion modes. The mass spectrometer was used in the scan range m / z 100 - 1.700 for MS and MS / MS. Used fragmentation of the 4th order. Primary mass spectrometric results showed the presence of 94 biologically active compounds corresponding to the species V. amurensis, moreover, salvianolic acids F, D and G, oleanoic, ursolic, myristoleic acids, berbericinin, mearnsetin, esculin, nevadensin, stigmasterol, fucosterol, phlorizin, L-tryptophan identified for the first time in V. amurensis.

Application of 1H and 13C NMR Fingerprinting as a Tool for the Authentication of Maltese Extra Virgin Olive Oil

The application of ¹H and ¹³C nuclear magnetic resonance (NMR) in conjunction with chemometric methods was applied for the discrimination and authentication of Maltese extra virgin olive oils (EVOOs). A total of 65 extra virgin olive oil samples, consisting of 30 Maltese and 35 foreign samples, were collected and analysed over four harvest seasons between 2013 and 2016. A preliminary examination of ¹H NMR spectra using unsupervised principle component analysis (PCA) models revealed no significant clustering reflecting the geographical origin. In comparison, PCA carried out on ¹³C NMR spectra revealed clustering approximating the geographical origin. The application of supervised methods, namely partial least squares discriminate analysis (PLS-DA) and artificial neural network (ANN), on ¹H and ¹³C NMR spectra proved to be effective in discriminating Maltese and non-Maltese EVOO samples. The application of variable selection methods significantly increased the effectiveness of the different classification models. The application of ¹³C NMR was found to be more effective in the discrimination of Maltese EVOOs when compared to ¹H NMR. Furthermore, results showed that different ¹H NMR pulse methods can greatly affect the discrimination of EVOOs. In the case of ¹H NMR, the Nuclear Overhauser Effect (NOESY) pulse sequence was more informative when compared to the zg30 pulse sequence, since the latter required extensive spectral manipulation for the models to reach a satisfactory level of discrimination.

Nutraceutical and Technological Properties of Buffalo and Sheep Cheese Produced by the Addition of Kiwi Juice as a Coagulant

Kiwifruit is an interesting alternative to chymosin for milk coagulation. Although the clotting properties of actinidin (the proteolytic agent present in kiwi) have been widely investigated, little is known about the nutraceutical and organoleptic effects of kiwifruit on the characteristics of cheese. We investigated kiwifruit pulp, compared to calf rennet, in cheesemaking using sheep and buffalo milk. Although the kiwifruit extract showed a longer coagulation and syneresis time than calf rennet, it could nevertheless be exploited as a plant coagulant due to its positive effect on the nutraceutical properties. In fact, the sheep and buffalo cheese were higher in polyphenols and phytosterols than the cheese obtained using calf rennet. In addition, the nutraceutical properties were enhanced, with just a slight effect on the aroma of the cheese.

Distribution of bioactives in entire mill chain from the drupe to the oil and wastes

Industrial olive oil production generates large amounts of by-products, mainly pomaces and wastewaters. The latter, in particular, represents serious environmental problems requiring special treatments prior to disposal. While olive pomace finds use as alternative energy source, wastewaters still remain a task since it is not reusable, representing an additional cost on olive oil for its treatments. This study is a "comprehensive" overview on the distribution of bioactives in entire mill chain from the drupe to the oil and wastes. Identification was achieved through liquid chromatography coupled with mass spectrometry, spectrofotometric and fluorimetric detection. Phenols resulted the most abundant class of substances, with the highest hydroxytyrosol amounts in wastewater (214 mg/kg). Pomace contained a total of 304 mg/kg in terms of bioactives, thus representing a potential food supplement ingredient for functional foods with high nutritional values.

Domestic Sautéing with EVOO: Change in the Phenolic Profile

(1) Background: The health benefits of extra-virgin olive oil (EVOO), a key component of the Mediterranean diet, are attributed to its polyphenol profile. EVOO is often consumed cooked, and this process may degrade and transform polyphenols. (2) Methods: In this work, we determined how temperature, time, and the interaction between them affects the EVOO polyphenolic profile during a domestic pan-frying process, simulating the cooking conditions of a home kitchen, without the control of light or oxygen. Applying a 22 full factorial design experiment, "Hojiblanca" EVOO was processed at two temperatures (120 °C and 170 °C) either for a short time or a long time, mimicking a domestic process, and polyphenol content was analyzed by UPLC-ESI-QqQ-MS/MS. (3) Results: Temperature degraded the polyphenols of EVOO during the sauté cooking process, whereas time had an effect on some individual phenols, such as hydroxytyrosol, but not on the total phenol content. The polyphenol content decreased by 40% at 120 °C and 75% at 170 °C compared to raw EVOO. (4) Conclusions: Cooked EVOO still meets the parameters of the EU's health claim.

Characterization of bioactive and nutraceutical compounds occurring in olive oil processing wastes

RATIONALE

Several bioactive compounds, including phenolic acids and secoiridoids, are transferred from olive drupes to olive oil during the first stage of production. Here, the characterization of these low molecular weight (LMW) compounds in olive oil and in closely related processing materials, like olive leaves (OL) and olive mill wastewaters (OMW), was faced up, for the first time, by matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry (TOF MS).

METHODS

A novel binary matrix composed of 1,8-bis(tetramethylguanidino)naphthalene (TMGN) and 9-aminoacridine (9AA) (1:1 molar ratio), displaying excellent ionization properties at low levels of laser energy, was employed in reflectron negative ion mode by a MALDI TOF/TOF system equipped with a neodymium-doped yttrium lithium fluoride (Nd:YLF) laser (345 nm). MS/MS experiments were performed by using ambient air as the collision gas.

RESULTS

Four major secoiridoids typically present in olive oil, i.e., the aglycones of oleuropein and ligstroside, and oleacein and olecanthal at m/z 377.1, 361.1, 319.1 and 303.1, respectively, were detected in virgin olive oil (VOO) extracts, along with some of their chemical/enzymatic hydrolysis by-products, such as elenolic (m/z 241.1), decarboxymethyl-elenolic acids (m/z 183.1) and hydroxytyrosol (m/z 153.1). Besides oleuropein aglycone and oleacein, hydroxylated derivatives of decarboxymethyl-elenolic acid and hydroxytyrosol were evidenced in OMW.

CONCLUSIONS

While oleuropein was confirmed in OL extracts, several interesting phenolic compounds, including hydroxytyrosol, were recognized in OMW. The proposed approach based on the use of a novel binary matrix for MALDI MS/MS analyses of LMW bioactive compounds can be considered a promising analytical tool for a rapid screening of the phenolic fraction in olive oils and related processing wastes.

Effects of Organic and Conventional Growing Systems on the Phenolic Profile of Extra-Virgin Olive Oil

Extra-virgin olive oil (EVOO) is largely appreciated for its proven nutritional properties. Additionally, organic foods are perceived as healthier by consumers. In this context, the aim of the present study was to compare the phenolic profiles of EVOO from olives of the Hojiblanca variety, cultivated under organic and conventional systems. The quantification and identification of individual polyphenols was carried out by liquid chromatography coupled to mass spectrometry in tandem mode (LC-MS/MS). Significantly higher levels (p < 0.05) of phenolic compounds were found in organic EVOOs. The methodology used was able to detect previously unreported differences in bioactive components between organic and conventional EVOOs.

Using Extra Virgin Olive Oil to Cook Vegetables Enhances Polyphenol and Carotenoid Extractability: A Study Applying the sofrito Technique

Olive oil is the main source of fat in the Mediterranean diet and the most frequently used ingredient in Mediterranean cuisine. Cooking with olive oil has been attracting attention because it can act as a food excipient, thereby increasing the bioaccessibility and bioavailability of ingested bioactive compounds. The aim of this study was to understand the effect of cooking with olive oil on the bioactive components in other ingredients (tomato, onion, and garlic) of sofrito sauce, a representative model of Mediterranean cuisine. After the cooking process, polyphenols from tomato, onion, and garlic were detected in the olive oil, especially naringenin, ferulic acid, and quercetin, as well as a high content of carotenoid Z-isomers, which are more bioavailable than the E-isomers. Therefore, traditional Mediterranean cuisine could play an important role in the health-improving effects of the Mediterranean diet.

Development and Validation of a QuEChERS-LC-MS/MS Method for the Analysis of Phenolic Compounds in Rapeseed Oil

In recent years, the determination of phenolic compounds in vegetable oil has aroused broad attention because these compounds have beneficial effects on health. In this work, a novel method based on the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method and LC-MS/MS was developed for the analysis of phenolic compounds. A total of 18 mL of acetonitrile, 3 mL of water, and 270 mg of C₁₈ sorbent were utilized in the optimized QuEChERS procedure. The LC-MS/MS analysis was performed in a C₁₈ column under gradient-elution conditions with eluent of acetonitrile and water with 0.1% acetic acid. The QuEChERS approach achieved decent extraction recoveries (75.32-103.93%) for most phenolic compounds. The QuEChERS-LC-MS/MS method was validated in terms of accuracy, precision, sensitivity, and linearity. The proposed method was further evaluated using different prepared rapeseed oils. The result demonstrated that QuEChERS-LC-MS/MS is a rapid and reliable method for determining phenolic compounds in rapeseed oils.

Insights into the Analysis of Phenolic Secoiridoids in Extra Virgin Olive Oil

Extra virgin olive oils (EVOOs) containing more than 5 mg/20 g tyrosol, hydroxytyrosol, and their secoiridoids can be recognized by health claims related to the protection of blood lipids from oxidative stress. Therefore, a reliable, accurate, and standardized analytical procedure is needed to determine these markers of EVOO quality. In order to overcome the limitations of current methods, a detailed investigation of sample preparation and chromatographic conditions was performed by UHPLC-UV-HRMS. The use of a C18 fused-core column and nonacidified gradient elution provided single, sharp peaks for oleocanthal and oleacein, allowing their reliable quantitation in UV profiles. Positive- and negative-UHPLC-HRMS/MS characterization of methanolic extracts revealed the presence of dimethyl acetal, methyl hemiacetal, and monohydrate derivatives of all secoiridoids. These artifacts were formed in aqueous methanol, which is usually employed to extract and analyze EVOO phenols, making the HPLC profiles more complex and the measurements less accurate and reproducible. Acetonitrile proved to be a suitable solvent to avoid the formation of secoiridoid dimethyl acetals and methyl hemiacetals and to efficiently extract EVOO bioactive phenols. Finally, the phenolic contents of Italian EVOO samples were determined by UHPLC-UV analysis of acetonitrile extracts before (direct method) and after acid hydrolysis (indirect method). The results indicated that the use of tyrosol and hydroxytyrosol as reference standards allowed more accurate quantitative data to be obtained. Direct and indirect methods provided comparable levels of EVOO phenols, highlighting the usefulness of acid hydrolysis in routine analyses. The improved procedure defines the most reliable conditions to provide an analytical method with suitable accuracy and repeatability in the analysis of healthy and functional EVOO phenols.

Quantitation of Oleuropein and Related Phenolics in Cured Spanish-Style Green, California-Style Black Ripe, and Greek-Style Natural Fermentation Olives

Oleuropein, ligstroside, and related hydrolysis products are key contributors to olive bitterness, and several of these phenolics are implicated in the prevention of lifestyle age-related diseases. While table olive processing methods are designed to reduce oleuropein, the impact of processing on ligstroside and related hydrolysis products (e.g., oleacein, oleocanthal, hydroxytyrosol glucoside, ligstroside aglycone, and oleuropein aglycone) is relatively unknown. Herein, levels of these compounds were measured in Spanish-style green (SP), Californian-style black ripe (CA), and Greek-style natural fermentation (GK) olives using rapid ultrahigh-performance liquid chromatography (UHPLC) tandem mass spectrometry (MS/MS). GK olives had the highest concentration of all compounds measured, with the exception of oleocanthal, which was highest in SP olives (0.081 mg kg^-1 wet weight (w.wt)). CA olives had the lowest levels of most compounds measured, including ligstroside (0.115 mg kg^-1 w.wt) and oleuropein (0.974 mg kg^-1 w.wt). Hydroxytyrosol was the predominate compound in all three styles of commercial olives, with similar concentrations observed for GK and SP olives (134.329 and 133.685 mg kg^-1 w.wt, respectively) and significantly lower concentrations observed for CA olives (19.981 mg kg^-1 w.wt).

Characterization and evaluation of phenolic profiles and color as potential discriminating features among Spanish extra virgin olive oils with protected designation of origin

Changes in phenolic profiles and color parameters can help to differentiate between extra virgin olive oils (EVOOs) with protected designation of origin (PDO). Phenolic profile characterization and CIELAB parameters determination of 9 PDO EVOOs from Spain were developed. Both properties of EVOOs are very relevant to their commercialization and increase the product value. The Serrana de Espadán olive cultivar was characterized for the first time and showed the highest pinoresinol concentrations and clarities in these olive oils, which are important values for the product image. To detect fraudulent instrumental work and implement quality control, principal component analysis (PCA) and linear discriminant analysis (LDA) were performed. EVOO geographical origin and cultivar distributions were achieved with cumulative variances of 93.4% and 92.4%, respectively. A categorization of PDO EVOOs was proposed using the following 7 phenolic compounds: phenolic alcohols (tyrosol and hydroxytyrosol), 3,4-DHPEA-EDA, 3,4-DHPEA-EA, p-HPEA-EDA, pinoresinol and total phenolic compounds.

State of the Art on Functional Virgin Olive Oils Enriched with Bioactive Compounds and Their Properties

Virgin olive oil, the main fat of the Mediterranean diet, is per se considered as a functional food—as stated by the European Food Safety Authority (EFSA)—due to its content in healthy compounds. The daily intake of endogenous bioactive phenolics from virgin olive oil is variable due to the influence of multiple agronomic and technological factors. Thus, a good strategy to ensure an optimal intake of polyphenols through habitual diet would be to produce enriched virgin olive oil with well-known bioactive polyphenols. Different sources of natural biological active substances can be potentially used to enrich virgin olive oil (e.g., raw materials derived from the same olive tree, mainly olive leaves and pomaces, and/or other compounds from plants and vegetables, mainly herbs and spices). The development of these functional olive oils may help in prevention of chronic diseases (such as cardiovascular diseases, immune frailty, ageing disorders and degenerative diseases) and improving the quality of life for many consumers reducing health care costs. In the present review, the most relevant scientific information related to the development of enriched virgin olive oil and their positive human health effects has been collected and discussed.

Olive oil polyphenols: A quantitative method by high-performance liquid-chromatography-diode-array detection for their determination and the assessment of the related health claim

In order to assess if an extra virgin olive oil (EVOO) can be acknowledged with the health claim related to olive oil polyphenols (Reg. EU n.432/2012), a new method to quantify these species in EVOO, by means of liquid-liquid extraction followed by HPLC-DAD/MS/MS of the hydroalcoholic extract, has been developed and validated. Different extraction procedures, different types of reverse-phase analytical columns (Synergi Polar, Spherisorb ODS2 and Kinetex) and eluents have been tested. The chromatographic column Synergi Polar (250×4.6mm, 4μm), never used before in this kind of application, provided the best results, with water and methanol/isopropanol (9/1) as eluents. The method allows the quantification of the phenolic alcohols tyrosol and hydroxytyrosol, the phenolic acids vanillic, p-coumaric and ferulic acids, secoiridoids derivatives, the lignans, pinoresinol and acetoxypinoresinol and the flavonoids luteolin and apigenin. The new method has been applied to 20 commercial EVOOs belonging to two different price range categories (3.78-5.80 euros/L and 9.5-25.80 euros/L) and 5 olive oils. The obtained results highlight that acetoxypinoresinol, ferulic acid, vanillic acid and the total non secoiridoid phenolic substances resulted to be significantly higher in HEVOOs than in LEVOOs (P=0.0026, 0.0217, 0.0092, 0.0003 respectively). For most of the samples analysed there is excellent agreement between the results obtained by applying the HPLC method adopted by the International Olive Council and the results obtained by applying the presented HPLC method. Results obtained by HPLC methods have been also compared with the ones obtained by the colorimetric Folin-Ciocalteu method.

Determination of eight polyphenols and pantothenic acid in extra-virgin olive oil samples by a simple, fast, high-throughput and sensitive ultra high performance liquid chromatography with tandem mass spectrometry method

A new ultra high performance liquid chromatography coupled with tandem mass spectrometry method for a fast and sensitive determination of eight polyphenols (hydroxytyrosol, catechin, epicatechin, epigallocatechin gallate, oleuropein, quercetin, rutin, tyrosol) and panthotenic acid in extra-virgin olive oil was developed. The method does not require long sample pre-treatment and presents the lowest limit of detection and limit of quantitation values present in literature. Inter- and intra-day variability, linear dynamic range of the calibration curve, recovery and matrix effect were also determined and investigated. The method was applied to several oil samples of different type and origin. Given its accuracy, precision and rapidity, the method is characterized by an interestingly high throughput, reliability, and sensitivity.

Extraction, Separation, and Identification of Phenolic Compounds in Virgin Olive Oil by HPLC-DAD and HPLC-MS

The aim of this study was to evaluate the recovery of individual phenolic compounds extracted from virgin olive oil (VOO), from different Greek olive varieties. Sufficient recoveries (90%) of all individual phenolic compounds were obtained using methanol as an extraction solvent, acetonitrile for residue solubilization, and two washing steps with hexane. Moreover, in order to elucidate structural characteristics of phenolic compounds in VOO, high performance liquid chromatography with a diode array detector (HPLC-DAD) at 280 and 340 nm and HPLC coupled to electrospray ionization mass spectrometry (HPLC-ESI-MS) in the negative-ion mode were performed. The most abundant phenolic compounds were oleuropein derivatives with m/z 319 and 377 and ligstroside derivatives with m/z 303, 361. Lignans, such as 1-acetoxypinoresinol and pinoresinol were also present in substantial quantities in the phenolic fraction. However, pinoresinol was co-eluted with dialdehydic form of ligstroside aglycone (DAFLA) and it was not possible to be quantified separately. The phenolic extracts, obtained from different VOO samples, yielded similar HPLC profiles. Differences, however, were observed in the last part of the chromatogram, corresponding to isomers of the aldehydic form of ligstroside aglycone. Oxidized phenolic products, originating from secoiridoids, were also detected.

In-depth assessment of analytical methods for olive oil purity, safety, and quality characterization

This paper evaluates the performance of the current analytical methods (standard and widely used otherwise) that are used in olive oil for determining fatty acids, triacylglycerols, mono- and diacylglycerols, waxes, sterols, alkyl esters, erythrodiol and uvaol, tocopherols, pigments, volatiles, and phenols. Other indices that are commonly used, such as free acidity and peroxide value, are also discussed in relation to their actual utility in assessing quality and safety and their possible alternatives. The methods have been grouped on the basis of their applications: (i) purity and authenticity; (ii) sensory quality control; and (iii) unifying methods for different applications. The speed of the analysis, advantages and disadvantages, and multiple quality parameters are assessed. Sample pretreatment, physicochemical and data analysis, and evaluation of the results have been taken into consideration. Solutions based on new chromatographic methods or spectroscopic analysis and their analytical characteristics are also presented.

Investigation of natural lipid-phenolic interactions on biological properties of virgin olive oil

There is limited knowledge regarding the impact of naturally occurring lipid-phenolic interactions on the biological properties of phenolics in virgin olive oil. Free and bound phenolics were isolated via sequential methanolic extraction at 30 and 60 °C, and were identified and quantified using reversed phase high performance liquid chromatography, liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS), and gas chromatography. Decreased oleic acid concentrations and increased concentrations of palmitoleic acid, stearic, linoleic, and linolenic acids were observed in virgin olive oil after removal of free and bound lipid phenolic compounds. The presence of p-hydroxybenzoic acid and tyrosol bound to glycerides was determined via LC-MS/MS, which indicates natural lipid-phenolic interactions in virgin olive oil. Both free and lipid bound phenolic extracts exerted antiproliferative activities against the CRC1 and CRC5 colorectal cancer cell lines. The present work indicates that naturally occurring lipid-phenolic interactions can affect the biological properties of phenolics in virgin olive oil.

Optimisation and validation of analytical methods for the simultaneous extraction of antioxidants: application to the analysis of tomato sauces

In the present study, simultaneous extraction of natural antioxidants (phenols and carotenoids) in complex matrices, such as tomato sauces, is presented. The tomato sauce antioxidant compounds studied were the phenolics hydroxytyrosol, from virgin olive oil, quercetin and its derivatives, from onions, and quercetin-rutinoside as well as the carotenoid, lycopene (cis and trans), from tomatoes. These antioxidant compounds were extracted simultaneously with n-hexane/acetone/ethanol (50/25/25, v/v/v). The phenolics were analysed by ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS), and lycopene (cis- and trans-forms) was analysed using high-performance liquid chromatography coupled to a diode array detector (HPLC-DAD). After studying the parameters of these methods, they were applied to the analysis of virgin olive oil, fresh onion, tomato concentrate and tomato powder, and commercial five tomato sauces. Subsequently, the results obtained in our laboratory were compared with those from the Gallina Blanca Star Group laboratory.