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This study documented seasonal levels of microplastics (MPs) and biomarkers (condition index, neurotoxicity, energy, oxidative stress) in mussels (Mytilus galloprovincialis), and water physico-chemical parameters in the Douro estuary (NE Atlantic coast), and estimated the human risk of MP intake (HRI) through mussels. Mussel stress was determined through the Integrated Biomarker Response (IBR). HRI was estimated from mussel MP concentrations and consumer habits. MPs were mainly micro-fibres (72 %) with varied chemical composition. Seasonal MP means (±SEM) in mussels ranged from 0.111 ± 0.044 (spring) to 0.312 ± 0.092 MPs/g (summer). Seasonal variations of mussel stress (IBR: 1.4 spring to 9.7 summer) and MP concentrations were not related. MeO-BDEs, PBDEs, temperature, salinity and other factors likely contributed to mussel stress variation. HRI ranged from 2438 to 2650 MPs/year. Compared to the literature, MP contamination in mussels is low, as well as the human risk of MP intake through their consumption. • Microplastic (MP) concentrations and biomarkers were studied in marine mussels. • Seasonal means (0.111 ± 0.044 to 0.312 ± 0.092 MPs/g) indicate low MP contamination. • Neurotoxicity and oxidative and energy stresses were observed (mainly in summer). • Seasonal variation trends of MP concentrations and stress levels were not related. • Human risk of MP intake through the consumption of Douro estuary mussels is low. [ABSTRACT FROM AUTHOR]

Highlights • Microwave assisted extractions of spent coffee grounds (SCG) polysaccharides were performed. • Temperature (T) and time (t) are the key factors in the microwave extraction. • Arabinogalactans (AG) extraction is favoured at 170 °C whereas galactomannans (GM) are favoured at lower T. • At 200 °C mainly GM oligosaccharides are recovered. • Alkali conditions protect against polysaccharides degradation at high T and low t. Abstract This work studies the microwave-assisted extraction conditions for recovery of polysaccharides from spent coffee grounds, including their effect on arabinogalactans and galactomannans polymerization and branching structural features. Temperature (140, 170, and 200 °C) has the most significant impact on total extracted mass (η total soluble solids) and sugars yield (η sugars), arabinogalactans (η AG) and galactomannans (η GM), and polysaccharide mass ratio (η AG / η GM). Time (2, 5, and 10 min) and alkali (diluted 0.1 M NaOH) treatments have less influence. Alkali treatment and shorter time (2 min) provided a protective effect against polysaccharides degradation. At 170 °C, the yield of arabinogalactans was found to be significantly higher than that of galactomannans (η AG / η GM >1). Increasing temperature to 200 °C leads to decrease the polymerization of polysaccharides, promoting the formation of debranched polysaccharides and oligosaccharides. This study shows that the optimum conditions for polysaccharides extraction cannot be selected only by mass yield but need to be defined according to the desired structural features for the specific applications. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Highlights: [•] The hepatoprotection of fifteen sesquiterpenoids was evaluated using rat hepatocytes. [•] Malonaldehyde level was reduced up to 35% (endogenous) and 70% (induced assays). [•] 3D-QSAR models were developed relating compounds activity with molecular properties. [•] Models showed good fit (R adj 2 >0.819) and prediction power (Q 2 >0.950). [•] A network of sesquiterpenoids structural features modulates the hepatoprotective activity. [Copyright &y& Elsevier]

Abstract: Electrochemical impedance spectroscopy was applied to the study of conducting lignin-derived polymers to be used in all-solid-state potentiometric chemical sensors. Conducting polymers were produced by step-growth polymerization of modified eucalyptus kraft lignin with isocyanate and doped by multi-wall carbon nanotubes (MWCNTs). Lignin possesses ion-exchange properties due to the presence of a variety of functional groups, which makes it an attractive active substance for chemical sensing. Co-polymerization allows fixing lignin inside polymer matrix ensuring high stability of the resulting material. Doping of the lignin-based polyurethane with multi-wall carbon nanotubes (MWCNTs) was adopted as a mean to obtain electrically conductive system with low mass of filler. The direct current (DC) electrical conductivity and the dielectric properties of the conducting polymers have been evaluated at MWCNTs contents from 0 to 0.72% (wt.) at the frequencies between 40Hz and 100MHz in the temperature range −100 to 100°C. The percolation model theory was used to describe DC and the low frequency behaviour, where the electrical conductivity and the dielectric constant were expressed by scaling laws near the threshold conduction. The lignin-based polyurethane presented low critical concentration of MWCNTs around 0.18wt.%. The dielectric analysis was carried out using the modulus formalism and the dielectric relaxation behaviour was modelled using the Cole–Cole expression. [Copyright &y& Elsevier]

Abstract: 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 α-[SiW11VIVO40]6−, α-[SiW11VVO40]5−, α-[BW11VIVO40]7−, α-[BW11VVO40]6−, α-[PW11VIVO40]5− and α-[PW12−n V n VO40](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 α-[SiW11VVO40]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. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

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. • Optimization of SPE method to determine dissolved OA in spiked synthetic seawater • The ability of plastic fragments to sorb OA followed the order of PS > EPS > > PP ≈ PET. • PFO model was appropriate to describe sorption kinetics of PS, EPS and PET. • During HABs, dissolved okadaic acid can sorb to random floating plastics. [ABSTRACT FROM AUTHOR]

Highlights • The volatile exometabolome of three strains of S. aureus was studied. • The volatile exometabolome each strain comprised in average 240 metabolites. • Hierarchical clustering analysis allowed the strains metabotyping. • Enterotoxic and non-enterotoxic strains exhibited distinct metabolomic profiles. Abstract 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract: 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. [Copyright &y& Elsevier]