Electrochemical taste sensor for unmasking extra-virgin olive oils adulterated with rancid or winey-vinegary olive oils

Olive oils may be commercially classified, in a decrease order of quality and economic value, as extra-virgin (EVOO), virgin (VOO) or lampante (LOO) olive oils, being quite prone to frauds. Thus legal protection regulations have been approved by the European Union Commission [1,2], being required the fulfilment of several physicochemical and sensory thresholds [3,4]. Unfortunately, the mixture of expensive olive oils with low quality oils aiming fraudulent economic revenue is still a common practice difficult to detect. In this work, a potentiometric electronic tongue (E-tongue) was used to detect adulteration of an EVOO with different added levels (2.5%, 5%, 10%, 20% and 40%; v/v) of an LOO with an intense sensory defect (rancid or wineyvinegary). Previously, similar electrochemical devices, also comprising lipid polymeric sensor membranes, showed to be able to give qualitative and/or quantitative responses towards basic taste sensations (acid, bitter, salty, sweet, and umami), positive sensory attributes (bitter, fruity, green and pungency) or defects (e.g., butyric, musty, putrid, winey-vinegary and zapateria) [5-8]. The E-tongue coupled with linear discriminant technique (based on the signal profiles of 19 or 20 E-tongue sensors, chosen using a simulated annealing meta-heuristic variable selection algorithm, for rancid and wineyvinegary adulterations, respectively) allowed to semi-quantitatively distinguish olive oils with different adulteration levels (repeated K-fold crossvalidation predictive correct classifications of 84±10% and 94±8% for rancid and winey-vinegary adulterations, respectively). The preliminary results showed the practical potential of the E-tongue as a taste device for the successful detection of EVOOs adulterated with LOO containing organoleptic defects.This work was financially supported by POCI- 01–0145-FEDER-006984–Associate Laboratory LSRE-LCM, Project UID/QUI/00616/2013 –CQVR, Project UID/BIO/04469/2013 – CEB and Project UID/AGR/00690/2013 –CIMO all funded by FEDER, through COMPETE2020, and by national funds through. Nuno Rodrigues thanks FCT, POPH-QREN and FSE for the Ph.D. Grant SFRH/BD/104038/2014.info:eu-repo/semantics/publishedVersio

Tunisian olive oils geographical origin discrimination using the potentiometric fingerprints recorded by an electronic tongue

The development of fast and cost-effective analytical techniques for EVOO authentication is a challenging task. Moreover, if a specific meteorological or geographical factor affects different geographical regions similarly, olive oils geographical discrimination may be a hard task using conventional analytical techniques [1]. E-noses and/or voltammetric E-tongues have already been applied to assess olive oils' geographical origin, mainly to discriminate different countries or quite different regions of the same country [2].This work was financially supported by POCI- 0 1-0 145-FEDER-006984-Associate Laboratory LSRE-LCM, Project UID/QUI/00616/2013 --CQVR, Project UID/BI0/04469/2013--CEB and Project UID/AGR/00690/2013--CIMO all funded by FEDER, through COMPETE2020, and by national funds through. Nuno Rodrigues thanks FCT, POPH-QREN and FSE for the Ph.D. Grant (SFRHIBD/104038/2014 ).info:eu-repo/semantics/publishedVersio

Unmasking admixtures of extra virgin olive oils with olive oils containing sensory defects using a multi-sensor taste device

Book of Abstracts of CEB Annual Meeting 2017This work was financially supported by Project POCI-01–0145-FEDER-006984 – Associate Laboratory LSRE-LCM, Project UID/QUI/00616/2013 – CQ-VR, Project UID/BIO/04469/2013 - CEB and Project UID/AGR/00690/2013 – CIMO all funded by FEDER - Fundo Europeu de Desenvolvimento Regional through COMPETE2020 - Programa Operacional Competitividade e Internacionalização (POCI) – and by national funds through FCT - Fundação para a Ciência e a Tecnologia, Portugal. Nuno Rodrigues thanks FCT, POPH-QREN and FSE for the Ph.D. Grant (SFRH/BD/104038/2014). Souheib Oueslati is grateful for the support of the Tunisian Ministry of Agriculture.info:eu-repo/semantics/publishedVersio

Evaluation of Tunisian olive oils from different cultivars

[Excerpt] Olive oil is a highly appreciated food product due to sensory and healthy attributes, being quite prone to frauds. So, physicochemical evaluation of olive oils is legally required. In this study, 43 olive oil samples produced in Tunisia from different olive cultivars (groups: Sahli cv – 11 samples; Chetoui cv- 26 samples; and, Other cvs – 4 samples including Leguim cv and Arbequina cv) were physicochemically evaluated taking into account: (i) free acidity (FA), K232 and K270 extinction coefficients, K, and, peroxide values (PV), required for quality level classification (i.e., extra-virgin, virgin and lampante olive oil: EVOO, VOO and LOO); and (ii) other useful data for olive oil overall characterization (total phenols (TP); antioxidant capacity (DPPH); and, oxidative stability (OS)). Based on the levels found for FA, PV and extinction coefficients (K232, K270 and K), the 43 olive oils were classified as: EVOO (4 samples), VOO (5 samples) and LOO (33 samples). [...]This work was financially supported by Project POCI-01-0145-FEDER-006984 – Associate Laboratory LSRE-LCM and by Project UID/QUI/00616/2013 – CQ-VR both funded by FEDER through COMPETE2020 - Programa Operacional Competitividade e Internacionalização (POCI) – and by national funds through FCT - Fundação para a Ciência e a Tecnologia. Strategic funding of UID/BIO/04469/2013 unit is also acknowledged. Nuno Rodrigues thanks FCT, POPH-QREN and FSE for the Ph.D. Grant (SFRH/BD/104038/2014)

Characterization of commercial Tunisian monovarietal olive oils produced from autochthonous olive cultivars

Tunisian commercial monovarietal olive oils, produced from two predominant autochthonous olive cultivars (cvs Chétoui and Oueslati) and another less investigated olive cultivar (cv Sahli) were studied. Chemical and sensory data have shown that most olive oils should be classified as lampante olive oil, pointing out the need of improving producing and/or storage conditions. Sahli olive oils showed the lowest total phenols content (157±48 mg/kg), oxidative stability (6.5±2.1 h), DPPH scavenging activity (68%±14) and monounsaturated fatty acids content (63.1%±3.1). These olive oils had the highest saturated and polyunsaturated fatty acids contents (19.9%±2.4 and 16.9%±1.4) as well as total tocopherols levels (222±49 mg/kg). Finally, the information of 12 selected parameters (total phenols, oxidative stability, nine fatty acids and -tocopherol), allowed establishing a linear discriminant model that correctly classified olive oils according to the olive cultivar with predictive rates of 90%±8. Heptadecenoic, behenic and eicosenoic acids were the three fatty acids identified as the most relevant chemical markers of Sahli olive oils.This work was financially supported by Project POCI-01– 0145-FEDER-006984 – Associate Laboratory LSRE-LCM, Project UID/QUI/00616/2013 – CQ-VR, and strategic project PEst-OE/AGR/UI0690/2014 – CIMO all funded by FEDER - Fundo Europeu de Desenvolvimento Regional through COMPETE2020 - Programa Operacional Competitividade e Internacionalização (POCI) – and by national funds through FCT - Fundação para a Ciência e a Tecnologia, Portugal. Strategic funding of UID/BIO/04469/2013 unit is also acknowledged. Nuno Rodrigues thanks FCT, POPH-QREN and FSE for the Ph.D. Grant (SFRH/BD/104038/2014). Souheib Oueslati is grateful for the support of the Tunisian Ministry of Agriculture.info:eu-repo/semantics/publishedVersio

A taste sensor device for unmasking admixing of rancid or winey-vinegary olive oil to extra virgin olive oil

Electrochemical sensor devices have gathered great attention in food analysis namely for olive oil evaluation. The adulteration of extra-virgin olive oil with lower-grade olive oil is a common worldwide fraudulent practice, which detection is a challenging task. The potentiometric fingerprints recorded by lipid polymeric sensor membranes of an electronic tongue, together with linear discriminant analysis and simulated annealing meta-heuristic algorithm, enabled the detection of extra-virgin olive oil adulterated with olive oil for which an intense sensory defect could be perceived, specifically rancid or winey-vinegary negative sensations. The homemade designed taste device allowed the identification of admixing of extra-virgin olive oil with more than 2.5% or 5% of rancid or winey-vinegary olive oil, respectively. Predictive mean sensitivities of 84±4% or 92±4% and specificities of 79±6% or 93±3% were obtained for rancid or winey-vinegary adulterations, respectively, regarding an internal-validation procedure based on a repeated K-fold cross-validation variant (4 folds×10 repeats, ensuring that the dataset was forty times randomly split into 4 folds, leaving 25% of the data for validation purposes). This performance was satisfactory since, according to the legal physicochemical and sensory analysis, the intentionally adulterated olive oil with percentages of 2.510%, could still be commercialized as virgin olive oil. It could also be concluded that at a 5% significance level, the trained panelists could not distinguish extra-virgin olive oil samples from those adulterated with 2.5% of rancid olive oil or up to 5% of winey-vinegary olive oil. Thus, the electronic tongue proposed in this study can be foreseen as a practical and powerful tool to detect this kind of worldwide common fraudulent practice of high quality olive oil.This work was financially supported by Project POCI-01–0145FEDER-006984 – Associate Laboratory LSRE-LCM, Project UID/QUI/ 00616/2013 – CQ-VR, Project UID/BIO/04469/2013 – CEB and strategic project PEst-OE/AGR/UI0690/2014 – CIMO all funded by FEDER - Fundo Europeu de Desenvolvimento Regional through COMPETE2020 - Programa Operacional Competitividade e Internacionalização (POCI) – and by national funds through FCT - Fundação para a Ciência e a Tecnologia, Portugal. Nuno Rodrigues thanks FCT, POPH-QREN and FSE for the Ph.D. Grant (SFRH/BD/104038/2014). Souheib Oueslati is also grateful for the support of the Tunisian Ministry of Agriculture.info:eu-repo/semantics/publishedVersio

Application of an electronic tongue for Tunisian olive oils' classification according to olive cultivar or physicochemical parameters

Olive oil commercialization has a great impact on the economy of several countries, namely Tunisia, being prone to frauds. Therefore, it is important to establish analytical techniques to ensure labeling correctness concerning olive oil quality and olive cultivar. Traditional analytical techniques are quite expensive, time consuming and hardly applied in situ, considering the harsh environments of the olive industry. In this work, the feasibility of applying a potentiometric electronic tongue with cross-sensitivity lipid membranes to discriminate Tunisian olive oils according to their quality level (i.e., extra virgin, virgin or lampante olive oils) or autochthonous olive cultivar (i.e., cv Chétoui and cv Shali) was evaluated for the first time. Linear discrimination analysis coupled with the simulated annealing variable selection algorithm showed that the signal profiles of olive oils hydroethanolic extracts allowed olive oils discrimination according to physicochemical quality level (classification model based on 25 signals enabling 84 ± 9% correct classifications for repeated K-fold cross-validation), and olive cultivar (classification model based on 20 signals with an average sensitivity of 94 ± 6% for repeated K-fold cross-validation), regardless of the geographical origin and olive variety or the olive quality, respectively. The results confirmed, for the first time, the potential discrimination of the electronic tongue, attributed to the observed quantitative response (sensitivities ranging from 66.6 to +57.7 mV/decade) of the E-tongue multi-sensors towards standard solutions of polar compounds (aldehydes, esters and alcohols) usually found in olive oils and that are related to their sensory positive attributes like green and fruity.This work was financially supported by Project POCI-01–0145-FEDER-006984–Associate Laboratory LSRE-LCM and by Project UID/QUI/00616/2013–CQ-VR both funded by FEDER—Fundo Europeu de Desenvolvimento Regional through COMPETE2020-Programa Operacional Competitividade e Internacionalização (POCI)—and by national funds through FCTFundação para a Ciência e a Tecnologia, Portugal. Strategic funding of UID/BIO/04469/2013 unit is also acknowledged. Nuno Rodrigues thanks FCT, POPH-QREN and FSE for the Ph.D. Grant (SFRH/ BD/104038/2014).info:eu-repo/semantics/publishedVersio

Classification of single-cultivar Tunisian olive oils according to the geographical origin using an electronic tongue

Developing analytical techniques for EVOO authentication is a challenging task. Moreover, if a specific meteorological or geographical factor affects different geographical regions similarly, olive oils' geographical discrimination may be a hard task. Improved classification of olive oils may be achieved by combining electrochemical fingerprints with multivariate statistical techniques. In this work, we used an electronic tongue, comprising 40 lipid membrane sensors, to extract suitable potentiometric fingerprints of Tunisian monovarietal olive oils that could be used in combination with linear discriminant analysis to classify olive oils according to the geographical origin.info:eu-repo/semantics/publishedVersio

Alternaria

Alternaria is one of the major mycotoxigenic fungal genera with more than 70 reported metabolites. Alternaria mycotoxins showed notably toxicity, such as mutagenicity, carcinogenicity, induction of DNA strand break, sphingolipid metabolism disruption, or inhibition of enzymes activity and photophosphorylation. This review reports on the toxicity, stability, metabolism, current analytical methods, and prevalence of Alternaria mycotoxins in food and feed through the most recent published research. Half of the publications were focused on fruits, vegetables, and derived products—mainly tomato and apples—while cereals and cereal by-products represented 38%. The most studied compounds were alternariol, alternariol methyl ether, tentoxin, and tenuazonic acid, but altenuene, altertoxins (I, II, and III), and macrosporin have been gaining importance in recent years. Solid-liquid extraction (50%) with acetonitrile or ethyl acetate was the most common extraction methodology, followed by QuEChERS and dilution-direct injection (both 14%). High- and ultraperformance liquid chromatography coupled with tandem mass spectrometry was the predominant determination technique (80%). The highest levels of alternariol and alternariol methyl ether were found in lentils, oilseeds, tomatoes, carrots, juices, wines, and cereals. Tenuazonic acid highest levels were detected in cereals followed by beer, while alternariol, alternariol methyl ether, tenuazonic acid, and tentoxin were found in legumes, nuts, and oilseeds

Mesoporous silica nanoparticles for the encapsulation of essential oils and the improvement of their activity against Fusasrium avenaceum and its production of enniatins

International audienceDespite the in vitro efficacy of various essential oils (EOs), their practical use to control toxigenic Fusarium spp is limited by their high volatility and sensitivity to UV and oxidation. Their nano-encapsulation can provide protection for the active volatile molecules and allow for a gradual release into the environment. Mesoporous silica nanoparticles (MSNPs) are inert, mechanically stable, stable in suspension in an aqueous medium and their specific surface area is very suitable for functionalization. We have used them for the encapsulation of EOs with antifungal and antimycotoxin activity Mesoporous silica nanoparticles synthesis tetraethyl orthosilicate (TEOS