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Improvement of dietary and ecological biodiversity, namely by exploring autochthonous varieties, is a key point to the construction of a more sustainable food system and planetary health. However, the environmental sustainability continues to face huge challenges, reflecting the importance of achieving a better understanding about the functional role of biodiversity in ecosystems. Thus, the main objective of this research is to contribute to the sustainable valorization of Sambucus nigra L. berries through a comprehensive approach to evaluate the effects of elderberry’s cultivar, harvest year, and plantation field on the physicochemical berry composition. Moreover, the nutritional value of elderberry juice and respective dried pomace was determined. This complementary information is of huge utility for the rational and, as much as possible, integral use of elderberries. The harvest year, followed by field and the interaction of harvest × field, accounted for the highest impact on the berry’s physicochemical parameters, indicating the importance of the combined impact of the macro- and mesoclimate conditions on plant metabolism. Elderberry juice and dried pomace are a good source of carbohydrates (ca. 12 and 82%, respectively) and have low amounts of fat (≤2.5%), making them low-energy foods. Dried pomace may also represent a potential alternative source of vegetal protein (ca. 6%).

Staphylococcal food poisoning is a disease that originates significant health and economic losses and is caused by Staphylococcus aureus strains able to produce enterotoxins. The aim of this work is to go further on the study of the volatile exometabolome of S. aureus using an advanced gas chromatographic technique. Enterotoxic and non-enterotoxic strains were assessed. The volatile exometabolome profile comprised 240 volatiles belonging to ten chemical families. This volatiles were mainly by-products of branched-chain amino acids and methionine degradation, pyruvate metabolism, diacetyl pathway, oxidative stress and carotenoid cleavage. Metabolites released by the first two pathways were produced in higher contents by the enterotoxic strains. This study add further insights to S. aureus volatile exometabolome, and also shows that by applying it, it is possible to distinguish strains of S. aureus by the number of produced enterotoxins, which is especially important from the food safety point of view.

The present study tested under laboratorial conditions the sorption of okadaic acid (OA), a lipophilic toxin produced by marine phytoplankton, onto 6-mm plastic circular fragments. Fragments (4 g L−1) of polyethylene terephthalate (PET), polypropylene (PP), expanded polystyrene (EPS) and non-expanded polystyrene (PS) were exposed for 96 h to seawater spiked with 10 ng mL−1 of OA. Results of the experiments showed a broad percentage of OA removed from the water by plastics after 48 h of exposure: 30 ± 5.1% (PET), 37 ± 9.5% (PP), 62 ± 7.1% (EPS) and 83 ± 1.9% (PS). Sorption appears to be highly influenced by polymer's characteristics, such as polarity and degree of crystallinity. Further studies are needed to clarify the effect of the contact area on sorption by expanded plastics. These results point to the plausible interaction of OA and plastics in coastal waters.

Chemometrics can be very useful for the classical field of UV–Vis determination of metals in aqueous solutions. A conventional approach consisting of using selective bands in a univariate mode is often not applicable to the real-world samples from e.g. hydrometallurgical processes, because of overlapping signals, light scattering on foreign particles, gas bubble formation, etc. And this is where chemometrics can do a good job. This paper overviews certain contributions to the field of multivariate data processing of UV–Vis spectra for seemingly simple case of metal detection in aqueous solutions. Special attention is given to applications in nuclear technology field.

This study reports the synthesis of polyurethane–lignin copolymer blended with carbon multilayer nanotubes to be used in all-solid-state potentiometric chemical sensors. Known applicability of lignin-based polyurethanes doped with carbon nanotubes for chemical sensing was extended to eucalyptus LignoBoost® kraft lignin containing increased amounts of polyphenolic groups from concomitant tannins that were expected to impart specificity and sensitivity to the sensing material. Synthesized polymers were characterized using FT-MIR spectroscopy, electrical impedance spectroscopy, scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry and are used for manufacturing of all solid-state potentiometric sensors. Potentiometric sensor with LignoBoost® kraft lignin-based polyurethane membrane displayed theoretical response and high selectivity to Cu (II) ions, as well as long-term stability.

Preparation of potentiometric and amperometric sensors with thin-film membranes based on molecularly imprinted polymers (MIP) is described. Spherical MIP microparticles with diameter below 1 μm are suitable for incorporation into the sensing membrane by the deposition of a conducting polymer on the electrode surface. This is achieved through electropolymerization from the suspension of MIP particles in monomer solution. Procedures of the synthesis of MIP particles, preparation of sensing membranes, and analytical application of potentiometric and amperometric sensors with MIP-modified membranes are described.

The evaluation of the variety suitability regarding each appellation’s specificities should be a strategy for maximizing the varieties’ oenological potential while contributing to the sustainable production of quality wines, keeping their typicity and rationalizing winemaking costs. Thus, the combination of several grape physicochemical attributes, modulated by climate and vineyard characteristics, providing knowledge for each grape variety’s oenological potential, is a relevant and reliable support for winemakers’ decisions. To prove this hypothesis, six mature grape varieties from three harvests, each one from three vineyard parcels with different topographical conditions from Bairrada Appellation (Portugal), were studied using analysis of variance–simultaneous components analysis (ASCA). The effects of harvest year and parcel on grape berry weight, pH, titratable acidity, total sugars, total phenolics, antiradical activity, and volatile composition in free and glycosidically-linked forms were analyzed. The compositional plasticity of autochthonous varieties (white Arinto and Bical and red Baga, Castelão, and Touriga Nacional) was observed. Sauvignon Blanc grape composition was significantly modulated by harvest. This study represents an important contribution for the maintenance of varieties’ biodiversity while contributing to establishing their peculiarities. Autochthonous varieties, if accurately exploited, can provide higher characteristic diversity than worldwide used varieties, an aspect to be more objectively taken into consideration by winemakers.

One of the obstacles to the practical use of the multisensor systems – electronic tongues is a drift, i.e. gradual change of the sensor characteristics occurring in the process of their exploitation. Sensor drift leads to the deterioration of the performance of the calibration model that was calculated before changes in the sensor responses occurred. Two approaches can be employed to deal with this phenomenon. One consists of regular re-calibration of the sensor array, which is effective but time and labor consuming. Alternatively, multivariate statistical methods can be applied to the calibration model update using small subset of the standard samples. While significant efforts have been directed to the development of the calibration transfer and calibration update techniques, they were mostly applied to the near infrared spectroscopic instruments. Very few works addressed this issue for the potentiometric sensor arrays. In the present study, applicability of calibration update methods including slope and bias correction, direct standardization using PLS2 regression and auto-associative neural network, calibration update by weighting, Tikhonov regularization and Joint Y-PLS regression to the sensor array data was evaluated. Calibration models for copper and lead quantification in mixed solutions of transition metals using an array of 7 potentiometric sensors was used as an example. Of all studied methods, weighting and JYPLS regression were shown to be the most effective permitting to reduce prediction error for new data to the level of cross-validation error for the initial data.

The integration of plant metabolomics to support preharvest fruit development studies can provide important insights into the biochemical mechanisms involved and lately support producers on harvesting management. A metabolomic-based strategy for fingerprinting of volatile terpenoids and norisoprenoids from Sambucus nigra L. berries from three cultivars, through ripening, was established. From 42 monoterpenic, 20 sesquiterpenic, and 14 norisoprenoid compounds, 48 compounds are reported for the first time as S. nigra berries components. Chemometric tools revealed that ripening was the factor that influenced more the volatile fraction profile and physicochemical parameters (pH, TS, and TSS), followed by cultivar. For the unripe stages, a higher overall content of the studied metabolites was observed, which gradually decreased over the ripening stages, being consistent for the three cultivars. These trends were mainly ruled by limonene, p-cymene, aromadendrene, beta-caryophyllene, and dihydroedulan, which might therefore be used by producers as an additional simple decision making tool in conjunction with physicochemical parameters.

Paralytic shellfish toxins (PSTs) are a group of toxins that cause paralytic shellfish poisoning through blockage of voltage-gated sodium channels. PSTs are produced by prokaryotic freshwater cyanobacteria and eukaryotic marine dinoflagellates. Proliferation of toxic algae species can lead to harmful algal blooms, during which seafood accumulate high levels of PSTs, posing a health threat to consumers. The existence of PST-transforming enzymes was first remarked due to the divergence of PST profiles and concentrations between contaminated bivalves and toxigenic organisms. Later, several enzymes involved in PST transformation, synthesis and elimination have been identified. The knowledge of PST-transforming enzymes is necessary for understanding the processes of toxin accumulation and depuration in mollusk bivalves. Furthermore, PST-transforming enzymes facilitate the obtainment of pure analogues of toxins as in natural sources they are present in a mixture. Pure compounds are of interest for the development of drug candidates and as analytical reference materials. PST-transforming enzymes can also be employed for the development of analytical tools for toxin detection. This review summarizes the PST-transforming enzymes identified so far in living organisms from bacteria to humans, with special emphasis on bivalves, cyanobacteria and dinoflagellates, and discusses enzymes’ biological functions and potential practical applications.

Preparation of potentiometric and amperometric sensors with thin-film membranes based on molecularly imprinted polymers (MIP) is described. Spherical MIP microparticles with diameter below 1 μm are suitable for incorporation into the sensing membrane by the deposition of a conducting polymer on the electrode surface. This is achieved through electropolymerization from the suspension of MIP particles in monomer solution. Procedures of the synthesis of MIP particles, preparation of sensing membranes, and analytical application of potentiometric and amperometric sensors with MIP-modified membranes are described.

Chalcogenide glass electrode was applied to the detection of mercury(II) activity in the saline bromide buffers and artificial seawater at the activity levels corresponding to the acute toxicity. Mercury(II) toxicity in artificial seawater buffers and estuarine water was assessed using bioassay based on the luminescence of the marine bacterium A. fischeri. Electrode could detect mercury activity in the artificial seawater at the level of acute toxicity, which corresponded to pHg 23.2 (time of exposure 5 min.). Both electrode and bioassay indicated higher Hg2+ activity/toxicity in the estuarine water collected in the contaminated area. Quantification of Hg2+ activity in estuarine water using the mercury-selective electrode requires calibration procedure to account for matrix effects.

Electronic tongue based on potentiometric chemical sensors and Fourier transform mid-infrared spectroscopy (FT-MIR) were evaluated as rapid tools for the prediction of gelatin index of red, white and rose wines. Gelatin index was measured using modified procedure, which was applicable not only to red but also to white and rose wines. Relationship between gelatin index and a set of chemical parameters, electronic tongue and FT-MIR data have been investigated using multi-block analysis method called common component and specific weight analysis (CCSWA). Calibration models for gelatin index prediction were calculated using partial least square (PLS) regression. Variable selection for the PLS models was done using Variable Importance in Prediction criterion. Quantification of gelatin index in red and rose wine was possible using both electronic tongue and FT-MIR data with adjusted R2 in prediction of 0.75 and 0.89 for rose and 0.83 and 0.87 for red wine, respectively.

Paralytic shellfish toxins (PSTs) are monitored in commercial bivalves in several countries in the world due to their toxicity to human consumers. The present work examines the application of an electronic tongue based on potentiometric chemical sensors to the quantification of PSTs in mussel extracts. The electronic tongue comprised six miniaturized sensors with solid inner contact and plasticized polyvinylchloride membranes. Calibration models were calculated by PLS regression using measurements in sixteen model mixed solutions containing four PSTs commonly found in bivalves from the Portuguese coast. Transfer of the calibration models to sample matrix was done by joint-PLS regression using measurements in five mussel extracts spiked with PST standards. Quantification of PSTs in extracts of naturally contaminated mussels, using the electronic tongue and updated calibration model, was in agreement with values of the chromatographic reference method. Those sensors alone or combined in an electronic tongue are useful tools for rapid screening of PST in bivalves.

We hypothesize that oxidative stress induced by trichloramine exposure during swimming could be related to etiopathogenesis of asthma among elite swimmers. Aim: To investigate the effect of a swimming training session on oxidative stress markers of asthmatic compared to non‐asthmatic elite swimmers using exhaled breath (EB) metabolomics. Methods: Elite swimmers annually screened in our department (n=27) were invited and those who agreed to participate (n=20, of which 9 with asthma) had EB collected (Tedlar® bags) before and after a swimming training session. SPME fiber (DVB/CAR/PDMS) was used to extract EB metabolites followed by a multidimensional gas chromatography analysis (GC×GC‐ToFMS). Dataset comprises eight metabolites end products of lipid peroxidation: five aliphatic alkanes (nonane, 2,2,4,6,6‐pentamethylheptane, decane, dodecane, and tetradecane) and three aldehydes (nonanal, decanal, and dodecanal). To assess exercise impact on lipid peroxidation markers, data were analyzed using principle component analysis (PCA), which was run on the original data set and on the data set constructed using differences in the metabolite total areas before and after exercise session. Results: Heatmap representation revealed that metabolites content decreased after exercise, both for control and asthma groups; however, the greater decrease was observed for controls. Asthmatics and controls did not form separated clusters; however, control swimmers demonstrated a more varied response to the exercise being dispersed along all score plot. Conclusion: In well‐trained athletes, swimming is associated with a decrease in oxidative stress markers independently of the presence of asthma, although a more pronounced decrease was seen in controls. European Regional Development Fund FEDER through the Competitive Factors Thematic Operational Programme (COMPETE) and FCT, Portugal, under projects PEST-C/QUI/UI0062/2013 (Research Unit 62/94 QOPNA) and PTDC/QUI-QUI/117803/2010.

Out of control proliferation of toxic phytoplankton, called harmful algal blooms (HABs), have a significant economic impact on bivalve aquaculture and harvesting in coastal waters. Some phytotoxins, such as paralytic shellfish toxins (PSTs), are of concern due to the life-threatening symptoms they can cause. Development of rapid and low-cost screening tools would be a welcome addition to the laboratory methodologies employed in routine monitoring programs. However, most of the assays and biosensors for the screening of PSTs, are restricted to a single target, saxitoxin (STX), which is the most potent PST. The present study aimed at developing an assay for the detection of N-sulfocarbamoyl PST&mdash, GTX5, which is one of the most abundant toxins in bivalves during G. catenatum blooms as found on the Portuguese coast. Enzymatic assay employing PSTs&rsquo, transforming enzyme&mdash, carbamoylase&mdash, was proposed. Carbamoylase was extracted and purified from the surf clam S. solida. Carbamoylase displayed similar specificity to both carbamate (STX) and N-sulfocarbamate toxins (GTX5 and C1+2) converting them into decarbamoyl saxitoxin (dcSTX) and decarbamoyl gonyautoxins 2+3 (dcGTX2+3), respectively. The enzymatic assay involved hydrolysis of GTX5 by carbamoylase and quantification of the product of enzymatic reaction, dcSTX, using a potentiometric chemical sensor. A potentiometric sensor with plasticized PVC membrane that displayed sensitivity to dcSTX and selectivity in the presence of GTX5 was employed. Enzymatic assay allowed determination of GTX5 in the concentration range from 0.43 to 3.30 &micro, molL&minus, 1, which encompasses levels of GTX5 in contaminated bivalve extracts with toxicities above PSTs regulatory limits. The feasibility of the carbamoylase-based potentiometric assay for detection of GTX5 was demonstrated.

This work reports on the development of a new voltammetric sensor for diphenylamine based on the use of a miniaturized gold electrode modified with a molecularly imprinted polymer recognition element. Molecularly imprinted particles were synthesized ex situ and further entrapped into a poly(3,4-ethylenedioxythiophene) polymer membrane, which was electropolymerized on the surface of the gold electrode. The thickness of the polymer layer was optimized in order to get an adequate diffusion of the target analyte and in turn to achieve an adequate charge transfer at the electrode surface. The resulting modified electrodes showed a selective response to diphenylamine and a high sensitivity compared with the bare gold electrode and the electrode modified with poly(3,4-ethylenedioxythiophene) and non-imprinted polymer particles. The sensor showed a linear range from 4.95 to 115 μM diphenylamine, a limit of detection of 3.9 μM and a good selectivity in the presence of other structurally related molecules. This sensor was successfully applied to the quantification of diphenylamine in spiked apple juice samples.

Lipidome profile of fluids and tissues is a growing field as the role of lipids as signaling molecules is increasingly understood, relying on an effective and representative extraction of the lipids present. A number of solvent systems suitable for lipid extraction are commonly in use, though no comprehensive investigation of their effectiveness across multiple lipid classes has been carried out. To address this, human LDL from normolipidemic volunteers was used to evaluate five different solvent extraction protocols [Folch, Bligh and Dyer, acidified Bligh and Dyer, methanol (MeOH)-tert-butyl methyl ether (TBME), and hexane-isopropanol] and the extracted lipids were analyzed by LC-MS in a high-resolution instrument equipped with polarity switching. Overall, more than 350 different lipid species from 19 lipid subclasses were identified. Solvent composition had a small effect on the extraction of predominant lipid classes (triacylglycerides, cholesterol esters, and phosphatidylcholines). In contrast, extraction of less abundant lipids (phosphatidylinositols, lyso-lipids, ceramides, and cholesterol sulfates) was greatly influenced by the solvent system used. Overall, the Folch method was most effective for the extraction of a broad range of lipid classes in LDL, although the hexane-isopropanol method was best for apolar lipids and the MeOH-TBME method was suitable for lactosyl ceramides.

The use of oak products as a cheaper alternative to expensive wood barrels was recently permitted in Europe, which led to a continuous increase in the use of oak chips and staves in winemaking. The feasibility of the potentiometric electronic tongue as a tool for monitoring the effects of wine maceration with oak chips was evaluated. Four types of commercially available oak chips subjected to different thermal treatments and washing procedures and their mixture were studied. Ethanolic extracts of the chips were analysed using electrospray mass spectrometry and 28 phenolic and furanic compounds were identified. The electronic tongue comprising 22 potentiometric chemical sensors could distinguish artificial wine solutions and Cabernet Sauvignon wine macerated with different types of oak chips, quantify total and non-flavonoid phenolic content, as well as the concentrations of added oak chips. Using measurements at two pH levels, 3.2 and 6.5, improved the accuracy of quantification.

We report the development of a low cost plastic optical fibre (POF) sensor for ammonium detection using molecularly imprinted polymers (MIP’s). The cladding of a 1 mm diameter PMMA fiber is removed, in which is grafted a molecular imprinted polymer (MIP), by radical polymerization with thermal initiation, that act as a selective sensing layer. For the polymerization, 2,2’-Azobis(2-methylpropionamidine)dihydrochloride (AAPH) is used as initiator, methacrylic acid (MAA) as a monomer, ethylene glycol dimethacrylate (EDMA) as a cross-linker, ammonium chloride (NH 4 Cl) as a template and 30% of ethanol in water as a solvent. The sensing method consists of an intensity based scheme. The response to different concentrations of ammonium solutions in water has been evaluated at room temperature. Solutions with (0 - 0.6) M concentration, with the corresponding refractive indexes varying between 1.3325 - 1.3387, at 25°C were used. The response of the fiber with the original cladding, and after cladding removal has been monitored and compared to the response given by the developed sensor. The response is very fast, less than 1 minute and reversible, which allows the continuum use of the sensor. Further developments are focused in optimization of MIP grafting procedure and sensor performance, in order to increase sensitivity.

International audience; Metabolomics has been increasingly explored to achieve an improved understanding of asthma. In the current observational and exploratory study, the first to have examined the relationship between oxidative stress extension, eosinophilic inflammation, and disease severity in asthmatic patients, metabolomics (using target aliphatic aldehydes and alkanes) was carried out using solid-phase microextraction (SPME) followed by a comprehensive two-dimensional gas chromatography coupled to mass spectrometry with a high-resolution time-of-flight analyzer (GC×GC-ToFMS). We were able to demonstrate that metabolomics can give valuable insights into asthma mechanisms once lipidic peroxidation assessed by urinary metabolomics is related to the clinical characteristics of nonobese asthmatics, such as disease severity, lung function, and eosinophilic inflammation. Nevertheless, considering our sample size, the obtained results require further validation using a much larger sample cohort.

Modified eucalyptus kraft lignin doped with multiwall carbon nanotubes (MWCNTs) was used as a macromonomer in step-growth polymerization with tolylene 2,4-diisocyanate terminated poly(propylene glycol) with the aim of producing a conductive copolymer for all-solid-state potentiometric chemical sensor applications. The crosslinked elastomeric polyurethane obtained was characterized by Fourier transform infrared attenuated total reflection spectroscopy, scanning electron microscopy, tunnelling electron microscopy and atomic force microscopy. Doping of lignin-based polyurethane with MWCNTs produced a significant enhancement of its electrical conductivity without deterioration of thermal and viscoelastic properties. The polymer composite displayed a low percolation threshold at an MWCNT concentration of 0.18% (w/w), which was explained by the oriented distribution of MWCNTs along lignin clusters. All lignin-based polyurethanes doped with MWCNTs at concentrations above the percolation threshold are suitable for sensor applications. Copyright © 2012 Society of Chemical Industry

Analytical results obtained in determining the perchlorate ion in individual and mixed solutions by direct potentiometry with separate chemical sensors and with an “electronic tongue” multisensor system were compared. Various anion-exchange compounds (quaternary ammonium salts and metalloporphyrins) and neutral complexation agents (trifluoroacetylbenzoic acid derivatives) were chosen as membrane-active components for sensors.

The review presents a short record of the evolution of chemical sensors (ion selective electrodes) and multisensor systems of an electronic tongue type, based on the organization principles similar to those of biological sensors. The main types of chemical sensors and multisensor electronic tongue combinations elaborated today are considered along with sensitive materials used in them. Recent advances in chemical sensors, for example, lower detection limits and so-called true selectivity are scrutinized. Also, some widespread analytical applications of electron tongues, including those for the identification and classification of liquid media, for the quantification of various components in there, for the control of industrial processes, as well as the type and intensity evaluation of the taste of food and medications are discussed.

A set of fourteen Madeira wines comprising wines produced from four Vitis vinifera L. varieties (Bual, Malvasia, Verdelho and Tinta Negra Mole) that were 3, 6, 10 and 17 years old was analysed using HPLC and an electronic tongue (ET) multisensor system. Concentrations of 24 organic acids, phenolic and furanic compounds were determined by HPLC. The ET consisting of 26 potentiometric chemical sensors with plasticized PVC and chalcogenide glass membranes was used. Significance of the effects of age and variety on the ET response and wine composition with respect to the organic acids, phenolics and furanic derivatives were evaluated using ANOVA-Simultaneous Component Analysis (ASCA). Significance of the effects was estimated using a permutation test (1000 permutations). It was found that effects of age, grape variety and their interaction were significant for the HPLC data set and only the effect of age was significant for the ET data. Calibration models of the HPLC and ET data with respect to the wine age and of the ET data with respect to the concentration of the organic acids and phenolics were calculated using PLS1 regression. Models were validated using cross-validation. It was possible to predict wine age from HPLC and ET data with the accuracy in cross-validation of 2.6 and 1.8 years respectively. The ET was capable of detecting the following components (mean relative error in cross-validation is shown in the parentheses): tartaric (8%), citric (5%), formic (12%), protocatehuic (5%), vanillic (18%) and sinapic (14%) acids, catechin (6%), vanillin (12%) and trans-resveratrol (5%). The ET capability of predicting Madeira wine age with good accuracy (1.8 years) as well as quantify of some organic acids and phenolic compounds was demonstrated. published

Electronic noses and tongues are analytical instruments based on an array of partially selective chemical sensors and multivariate data processing tools. They have become popular analytical tools during the last two decades and a wide range of applications have been reported. Such tasks as classification of samples according to the properties of interest, quantification, process control and taste and flavour prediction have been addressed. This review deals with the applications of electronic nose and tongue systems to the food analysis published in the last 5 years. The review is organized according to food type rather than type of system or analytical task. Also a brief history of the development of electronic noses and tongues is presented. An overview of existing sensor systems and types of sensors used in them is given together with the information about commercial instruments. Practical aspects of electronic nose and tongue application are briefly discussed.

The present study deals with the evaluation of the electronic tongue multisensor system as an analytical tool for the rapid assessment of taste and flavour of beer. Fifty samples of Belgian and Dutch beers of different types (lager beers, ales, wheat beers, etc.), which were characterized with respect to the sensory properties, were measured using the electronic tongue (ET) based on potentiometric chemical sensors developed in Laboratory of Chemical Sensors of St. Petersburg University. The analysis of the sensory data and the calculation of the compromise average scores was made using STATIS. The beer samples were discriminated using both sensory panel and ET data based on PCA, and both data sets were compared using Canonical Correlation Analysis. The ET data were related to the sensory beer attributes using Partial Least Square regression for each attribute separately. Validation was done based on a test set comprising one-third of all samples. The ET was capable of predicting with good precision 20 sensory attributes of beer including such as bitter, sweet, sour, fruity, caramel, artificial, burnt, intensity and body.

The history of development of “electronic tongue” multisensor systems whose operation is underlain by principles close to those in biological sensory systems was briefly overviewed. The main types of “electronic tongue” systems developed by now were described, along with sensor materials and sensors applied in such systems. The most widespread applications of “electronic tongues” were discussed including those for recognition and classification of liquid media, quantitative analysis of various components in these liquids, smart monitoring of industrial processes, and evaluation of the type and intensity of the flavor of various foodstuffs and drugs.

A sensor array comprising potentiometric chemical sensors with solvent polymeric and chalcogenide glass membranes was developed and applied to the determination of copper, zinc, lead and cadmium ions’ activity at the nmol L−1 concentration levels. Sensors were able to detect copper down to the 0.2 nmol L−1, lead 0.4 nmol L−1, cadmium 0.06 nmol L−1 and zinc 30 nmol L−1 in individual buffer solutions. Collinearity of the sensors’ responses in the buffer and non buffer solutions confirms sensors’ sensitivity to these metals at the very low activity levels. Sensor array was capable to determine simultaneously these cations in the mixed buffer solutions at the background of 0.5 mol L−1 sodium chloride or artificial seawater with the accuracy of about 20%. Copper and zinc could be detected in the mixed solutions down to the concentration of 1 nmol L−1 and lead and cadmium at the concentration of 2 nmol L−1. Therefore, the sensor array is suitable for the detection of copper and zinc at the concentrations corresponding to the chronic seawater criteria, and lead and cadmium at the concentrations corresponding to the acute seawater criteria. The sensor array based on the potentiometric chemical sensors demonstrated a good promise as an instrument for rapid measurements of the ultra-low activities of copper, lead, zinc and cadmium in seawater.

Fermentation is one of the oldest methods of the food processing and preservation. In the industrial setting, real-time monitoring of the fermented media composition is of paramount importance for the effectiveness of the whole process. However, analytical instruments used for these processes’ monitoring remain relatively primitive. Lack of online sensors for fermentation monitoring is commonly stressed in the literature. One of the techniques particularly suitable for this purpose is the electronic tongue based on the chemical sensors. This chapter presents recent achievements in the applications of electronic tongues to the monitoring of the fermentation processes employed for the food production. Types of the electronic tongues used and types of analysis performed; that is, quantification of the components or process monitoring and fault detection are described. Applications to the model case studies and real processes used for the production of foods and food ingredients are covered.

The electronic tongue multisensor system was applied to the measurements in about 160 samples of the Port wines of different ages (from 2 to 70 years old) and of different types including Tawnies, Vintages, Late Bottled Vintage (LBV) and harvest wines. Multivariate calibration for the prediction of the Port wine age was made applying PLS regression to the electronic tongue and chemical analysis data. Orthogonal signal correction (OSC) was evaluated as data pre-processing method. OSC filtering was applied to the both data sets and the results were compared. The age of the Port wine was predicted with similar accuracy using both electronic tongue and chemical analysis data. The accuracy of age prediction was improved to about 1.5 years when using only the samples aged from 10 to 35 years for the calibration. This appears to be acceptable for the practical applications.

Automatic detection of clinical mastitis is an essential part of high performance and robotic milking. Currently available technology (conductivity monitoring) is unable to achieve acceptable specificity or sensitivity of detection of clinical mastitis or other clinical diseases. Arrays of sensors with high cross-sensitivity have been successfully applied for recognition and quantitative analysis of other multicomponent liquids. An experiment was conducted to determine whether a multisensor system (“electronic tongue”) based on an array of chemical sensors and suitable data processing could be used to discriminate between milk secretions from infected and healthy glands. Measurements were made with a multisensor system of milk samples from two different farms in two experiments. A total of 67 samples of milk from both mastitic and healthy glands were in two sets. It was demonstrated that the multisensor system could distinguish between control and clinically mastitic milk samples (p = 0.05). The sensitivity and specificity of the sensor system (93 and 96% correspondingly) showed an improvement over conductivity (56 and 82% correspondingly). The multisensor system offers a novel method of improving mastitis detection.

The electronic tongue (ET) multisensor system has been employed for the detection of metal-oxygen cluster anions (polyoxometalates) containing vanadium (IV/V) atoms. Sensitivity of a variety of potentiometric chemical sensors with plasticized polyvinyl chloride and chalcogenide glass membranes was evaluated with respect to vanadyl/vanadate ions, decavanadate and a series of Keggin-type polyoxometalates (POM) such as alpha-[SiW(11)V(IV)O(40)](6-), alpha-[SiW(11)V(V)O(40)](5-), alpha-[BW(11)V(IV)O(40)](7-), alpha-[BW(11)V(V)O(40)](6-), alpha-[PW(11)V(IV)O(40)](5-) and alpha-[PW(12-n)V(n)(V)O(40)]((3+n)-) (n=1, 2, 3). Sensor's responses to vanadium complexes were evaluated in the pH range of 2.4-6.5 and a set of sensors appropriate for detecting a variety of vanadium species was selected. Such sensor array was able to distinguish different vanadium complexes allowing their simultaneous quantification in binary (V(IV)/V(V)) mixtures. The vanillyl alcohol oxidation with alpha-[SiW(11)V(V)O(40)](5-) was monitored using ET to evaluate the capacity of proposed analytic system to detect simultaneously V(IV)/V(V) in POM under dynamic equilibrium. ET was demonstrated to be a promising tool for the discrimination and quantification of vanadium-containing POMs at different oxidation states. In particular, such a system could represent a significant interest for the mechanistic studies of redox reactions with POMs.

The present study was aimed at application of rapid analytical techniques such as Electronic Tongue and FTIR spectroscopy to the recognition and quantitative analysis of different apple varieties. Five apple varieties were studied using three different analytical techniques: HPLC, electronic tongue multisensor system based on potentiometric chemical sensors and FTIR spectroscopy. Twenty samples (apples) of each variety were measured. Concentrations of organic acids such as malic, citric, galacturonic etc. and sugars were measured by HPLC, which is a conventional method for fruit analysis. HPLC data were used as reference for calibration of the electronic tongue and FTIR. Different aspects of data processing were addressed. Recognition and classification of the apples according to variety was performed by PCA and PLS DISCRIM using the data from three different analytical instruments. Quantitative calibration of the electronic tongue and FTIR with respect to organic acids content was performed using PLS regression. Different approaches to data merging from two different analytical instruments, ET and ATR-FTIRT, were considered. Low-level data fusion was found to be the most effective for ET and ATR-FTIR.

The electronic tongue and attenuated total reflectance–Fourier transform infrared spectroscopy (ATR–FTIR) have been evaluated as novel rapid techniques in taste research. The electronic tongue, consisting of 27 potentiometric sensors, and ATR–FTIR, a well-established spectroscopic technique, have been used to determine the sugar and acid profile of four tomato cultivars: Aranca, Climaks, Clotilde and DRW 73-29. The most abundant sugars (glucose, fructose and sucrose) and organic acids (citric acid, malic acid, tartaric acid, fumaric acid and succinic acid) in tomatoes were measured with HPLC as a traditional reference technique. The ability of the novel techniques to detect differences in sugar and acid profiles between these four tomato cultivars has been studied by means of unsupervised and supervised multivariate data analysis techniques such as principal components analysis (PCA) and canonical discriminant analysis (CDA). Canonical correlation analysis (CCA) was applied to compare the information content of the reference technique with that of the electronic tongue and ATR–FTIR. The potential of both the electronic tongue and ATR–FTIR to predict the chemical composition of a sample has been evaluated using partial least squares (PLS) models. Both the electronic tongue and ATR–FTIR have the potential to measure taste determining compounds. Tomato cultivars can be classified based on their sugar and acid profile. However, the prediction of individual components in tomato juice is still inaccurate and needs further optimization.

The aim of the present study was application of the electronic tongue multisensor system (ET) for discrimination of cork both standard and Mancha Amarela (Yellow spot). Extracts of cork in 10% ethanol water solutions were analysed. Two sets of cork samples that included both standard (S) and Mancha Amarela (MA) cork samples from two different factories were studied. It was found that ET could reliably distinguish extracts made from S and MA cork regardless samples’ origin. ET could predict total phenols’ content with average precision of 9% when calibrated using reference data obtained by Folin–Ciocalteu method. The ET was demonstrated to be promising tool for the cork quality evaluation. Difference in composition between S and MA cork was studied by ET. The largest difference in concentration between two types of cork extracts was found for gallic and protocatechuic acids.

A variety of novel sensing materials on the basis of phosphine oxides for solvent polymeric sensors have been developed and studied. It was found that phosphine oxide sensors exhibit good sensitivity to rare earth metal cations, such as La3+, Pr3+, Nd3+, Eu3+ and also to Y3+. Polymeric sensors can be comprised into electronic tongue sensor arrays that may allow detection of several rare-earth metal ions simultaneously in mixed solutions. Such sensor arrays are highly promising for environmental and industrial sensing, e.g., for analysis of spent nuclear fuel.

Rapid quality assessment of alcoholic beverages, including brand identification and detection of products of unacceptable quality or counterfeits is an important practical task. In the present work the multisensor electronic tongue system (ET), based on array of potentiometric chemical sensors was applied to recognition and classification of spirits such as vodka and ethanol used for vodka production and also for eau-de-vie in cognac production. The ET system was capable of detecting presence of contaminant substances in vodka in concentrations exceeding allowed levels as well as of distinguishing vodka complying and not complying with state quality standards. Ten brands of vodka produced at the same distillery using water and ethanol of different purity and various taste additives were discriminated using the instrument. The ET could distinguish synthetic and alimentary grain ethanol as well as alimentary ethanol of different grades (i.e. different degree of purification). A feasibility study was run on several eau-de-vie samples, which included fresh and aged eau-de-vie as well as samples produced using different distillation technology and samples kept in contact with different kinds of oak. The electronic tongue showed a promise as an analytical instrument for rapid quality assessment of spirits.

Application of chemometric methods to processing of the dynamic response of a flow-injection multiple-sensor system of the “electronic tongue” type is described. A through flow-injection multiple-sensor system of a new type is developed. The data processing is carried out using the method of projection to latent structures and the n-variate method of projection to latent structures (in processing of three-dimensional data). The results obtained in determining ions of lead and zinc in the case of their simultaneous presence in solution and comparative characteristics of various calibration models are presented.

Udgivelsesdato: 20.10 A potentiometric electronic tongue (ET) consisting of eight cross-sensitive chemical sensors and a standard pH electrode has been appliedfor analysis of simulated fermentation solutions typical for fermentation processes with Aspergillus niger . The electronic tongue has been found capable of simultaneous determination of ammonium, citrate and oxalate in complex media with good precision (typical error within 8%). The system preserved high sensitivity to the targeted substances also in the presence of sodium azide, which is commonly used for suppressing microbial activity in real-world fermentation samples. Sensor performance was fast and reproducible which promises well for routine application of the electronic tongue for fermentation process monitoring.

An electronic tongue comprising 21 potentiometric chemical sensors with pattern recognition tools was used for the rapid off-line monitoring of batch Escherichia coli fermentations. The electronic tongue was capable of monitoring the changes in the media composition as the fermentation progressed, and could correlate this with an increase in biomass. The electronic tongue was also able to monitor the increase in organic acids, especially acetic acid, throughout the fermentation. This technique clearly shows promise as a rapid tool for fermentation monitoring.

The electronic tongue based on a sensor array comprising 23 potentiometric cross-sensitive chemical sensors and pattern recognition and multivariate calibration data processing tools was applied to the analysis of Italian red wines. The measurements were made in 20 samples of Barbera d’Asti and in 36 samples of Gutturnio wine. The electronic tongue distinguished all wine samples of the same denomination and vintage, but from different vineyards. Simultaneously the following quantitative parameters of the wines were measured by the electronic tongue with precision within 12%: total and volatile acidity, pH, ethanol content, contents of tartaric acid, sulphur dioxide, total polyphenols, glycerol, etc. The electronic tongue is sensitive to multiple substances that determine taste and flavour of wine and, hence, the system was capable of predicting human sensory scores with average precision of 13% for Barbera d’Asti wines and 8% for Gutturnio wines.

Electronic tongues for liquid analysis, based on the organizational principles of biological sensory systems, developed rapidly during the last decade. A brief historical overview of the research and development in the field of electronic tongue systems is presented. Current achievements of scientific groups working in this field are outlined and critically reviewed. The performance of electronic tongues in quantitative analysis and in classification of multicomponent media is considered. The exciting possibility of establishing a correlation between the output from an electronic tongue and human sensory assessment of food flavour, thereby enabling quantification of taste and flavour, is described. Application areas of electronic tongue systems including foodstuffs, clinical, industrial, and environmental analysis are discussed in depth. Prospective research and development in the field of electronic tongues is discussed.

An electronic tongue comprising thirty potentiometric chemical sensors and pattern recognition tools for data processing was used for the analysis of mineral waters, coffee, soft drinks and flesh food, namely fish. The electronic tongue appeared to be capable of distinguishing between different sorts of beverages: natural and artificial mineral waters, individual and commercial brands of coffee, and commercial and experimental samples of soft drinks containing different sweeteners. A quantitative correlation between human perception and `electronic tongue' output was obtained. Taste parameter assessments produced by a professional taste panel was used for `electronic tongue' calibration. It was found that the `electronic tongue' is capable of distinguishing sea water and freshwater fish and monitoring their spoilage.

Multisensor systems for liquid analysis based on chemical sensor arrays and pattern recognition, which are now widely known as ‘electronic tongues’, represent one of the most rapidly emerging and exciting fields of non-classical analytics during the last decade. This chapter presents an overview of the research and development of electronic tongue systems and describes various sensors, sensor arrays, and their numerous applications. A sound basis for electronic tongues was provided by the extensive development of well-known selective sensors, especially electrochemical, and biological inspirations originating from sensory systems of mammalians. The up-to-date achievements of various scientific groups working in this field are reviewed. The performance of electronic tongues in the tasks of recognition (classification, identification, discrimination) of multicomponent media is considered. A useful option of multicomponent quantitative analysis with the help of electronic tongues is also reported. The correlation between the output of an electronic tongue and human sensory assessments of food flavor made by taste panel opens up an exciting possibility of measuring and quantifying the taste and flavor of foods. Application areas of the electronic tongue systems, including quality control of foodstuffs, clinical, industrial and environmental analysis, are surveyed. Future prospects for research and development of electronic tongues are discussed.