Evaluation of the effect of extracted time conditions on the phenolic content of olive pastes from cv. Arbequina and discrimination using a lab-made potentiometric electronic tongue

The present study investigated the effect of malaxation times (Mt) (0, 15, 30, 45 and 60 min), during the industrial extraction of cv. Arbequina oils at 25 °C on total phenolic content of olive pastes. Additionally, the possibility of applying a lab-made potentiometric electronic tongue (E-tongue), comprising 40 lipid/polymer sensor membranes with cross sensitivity, to discriminate the olive pastes according to the Mt, was evaluated. The results pointed out that the olive pastes’ total phenolic contents significantly decreased (p-value < 0.001, one-way ANOVA) with the increase of the Mt (from 2.21 ± 0.02 to 1.99 ± 0.03 g gallic acid equivalents/kg olive paste), there being observed a linear decreasing trend (R-Pearson = −0.910). These findings may be tentatively attributed to the migration of the phenolic compounds from the olive pastes to the extracted oil and water phases, during the malaxation process. Finally, the E-tongue signals, acquired during the analysis of the olive pastes’ methanolic extracts (methanol:water, 80:20 v/v), together with a linear discriminant analysis (LDA), coupled with a simulated annealing (SA) algorithm, allowed us to establish a successful classification model. The E-tongue-LDA-SA model, based on 11 selected non-redundant sensors, allowed us to correctly discriminate all the studied olive pastes according to the Mt (sensitivities of 100% for training and leave-one-out cross-validation). The satisfactory performance of the E-tongue could be tentatively explained by the known capability of lipid/polymeric sensor membranes to interact with phenolic compounds, through electrostatic interactions and/or hydrogen bonds, which total content depended on the Mt.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support by national funds FCT/MCTES to CIMO (UIDB/00690/2020), to CEB (UIDB/04469/2020), to REQUIMTE-LAQV (UIDB/50006/2020) and to BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020—Programa Operacional Regional do Norte. Ítala Marx acknowledges the Ph.D. research grant (SFRH/BD/137283/2018) provided by FCT. Nuno Rodrigues thanks the National funding by FCT-Foundation for Science and Technology, P.I., through the institutional scientific employment program contract.info:eu-repo/semantics/publishedVersio

Olive oils qualitative evaluation using a potentiometric electronic tongue: a review of practical applications

Olive oil is a food product highly prone to fraud, including mislabeling of olive oil commercial category, geographical or olive cultivar origin. Several analytical techniques have been reported to assess olive oil quality, authenticity as well as to detect possible adulterations, namely gas-, liquid- and mass-spectrometry chromatography, DNA and spectroscopy based methods. However, in general, these techniques require expensive pre-sample treatments, are time-consuming and need cost equipments and high skilled technicians. So, fast and more cost-effective methods are still needed and their development a challenge. Among these, electrochemical sensors have been proposed within this field of research, including both voltammetric and potentiometric electronic noses and electronic tongues, individually or as a fused methodology. In this study it is intended to review some of the most recent applications described in the literature including those of the research team regarding the application of a potentiometric electronic tongue, containing cross-sensitive lipidic membranes, to discriminate single-cultivar extra-virgin olive oils by cultivar or sensory intensity, showing its range of applicability and the possibility of using this artificial taste sensor as a complementary/alternative methodology for olive oil sensory analysis.info:eu-repo/semantics/publishedVersio

Evaluation of cheese authenticity and proteolysis by HPLC and urea-polyacrylamide gel electrophoresis

Chromatographic and electrophoretic methods have been established as useful tools in characterising cheese ripening and in the detection of milk adulteration. The purpose of this work was to evaluate casein proteolysis of cheeses made from bovine, ovine or mixtures of bovine and ovine milks, as well as ovine cheese authenticity, for 30 days of ripening by HPLC and urea–polyacrylamide gel electrophoresis. Complementary information was obtained by both techniques when applied to the study of casein proteolysis during 30 days of ripening of ovine milk cheeses, ovine milk cheeses with 10% and 20% of bovine milk and bovine milk cheeses, manufactured according to the traditional Terrincho technology. For ovine cheeses, a-casein was the fraction that showed the higher degradation during cheese ripening. A similar behaviour was observed for ovine milk cheese with 10% of bovine milk. The profile for ovine milk cheese with 20% of bovine milk was more similar to that obtained for bovine cheese. Concerning bovine milk cheeses, electrophoresis was the most sensitive technique for the evaluation of proteolysis in these cheeses. Ten and 20% of bovine milk could be detected in ovine milk cheeses by urea–polyacrylamide gel electrophoresis and HPLC, respectively, even after 30 days of ripening.Project Agro No. 26, Medida 8, Acção 8.

An electronic nose as a non-destructive analytical tool to identify the geographical origin of portuguese olive oils from two adjacent regions

The geographical traceability of extra virgin olive oils (EVOO) is of paramount importance for oil chain actors and consumers. Oils produced in two adjacent Portuguese regions, Côa (36 oils) and Douro (31 oils), were evaluated and fulfilled the European legal thresholds for EVOO categorization. Compared to the Douro region, oils from Côa had higher total phenol contents (505 versus 279 mg GAE/kg) and greater oxidative stabilities (17.5 versus 10.6 h). The majority of Côa oils were fruity-green, bitter, and pungent oils. Conversely, Douro oils exhibited a more intense fruity-ripe and sweet sensation. Accordingly, different volatiles were detected, belonging to eight chemical families, from which aldehydes were the most abundant. Additionally, all oils were evaluated using a lab-made electronic nose, with metal oxide semiconductor sensors. The electrical fingerprints, together with principal component analysis, enabled the unsupervised recognition of the oils’ geographical origin, and their successful supervised linear discrimination (sensitivity of 98.5% and specificity of 98.4%; internal validation). The E-nose also quantified the contents of the two main volatile chemical classes (alcohols and aldehydes) and of the total volatiles content, for the studied olive oils split by geographical origin, using multivariate linear regression models (0.981 < R2 < 0.998 and 0.40 < RMSE < 2.79 mg/kg oil; internal validation). The E-nose-MOS was shown to be a fast, green, non-invasive and cost-effective tool for authenticating the geographical origin of the studied olive oils and to estimate the contents of the most abundant chemical classes of volatiles.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support by national funds FCT/MCTES (PIDDAC) to CIMO (UIDB/00690/2020 and UIDP/00690/2020), to CEB (UIDB/04469/2020) and to the Associate Laboratory SusTEC (LA/P/0007/2020). The authors are also grateful to the “Project OLIVECOA—Centenarian olive trees of Côa Valley region: rediscovering the past to valorize the future” (ref. COA/BRB/0035/2019), financed by FCT (Portugal). Nuno Rodrigues thanks the National funding by FCT- Foundation for Science and Technology, P.I., through the institutional scientific employment program-contract.info:eu-repo/semantics/publishedVersio

Pomegranate peels and seeds as a source of phenolic compounds: effect of cultivar, by-product, and extraction solvent

The nutraceutical properties of Punica granatum L. are not restricted to the edible portion of the fruit but also to the peels and seeds, flowers, leaves, and tree bark. The recovery and valorization of the peel and seeds (ca. 50% of the whole fruit), besides the positive environmental impact, can be viewed as a source of natural bioactive compounds. Thus, the bioactive properties of extracts of pomegranate peel and seeds from Acco and Wonderful known cultivars, as well as of the novel Big Full cultivar, were evaluated. The dried and ground pomegranate by-products were submitted to a conventional solid/liquid extraction with ethanol/water mixtures (0%, 25%, 50%, and 75% of EtOH, v/v). The obtained extracts were characterized in terms of total phenolic compounds (TPC), total flavonoids (TF), and antioxidant activity (AA), determined by the DPPH radical scavenging activity and expressed as IC50 (half maximum inhibitory concentration). With the exception of the Acco cultivar, the extraction yield (EY) was higher for peels, whose extracts showed higher TPC, TF, and IC50 (lower AA). The extracts obtained from the by-products of the Big Full cultivar had a statistically higher overall bioactive potential (TPC: 0.36 mg GAE/mg extract; TF: 0.031 mg CATE/mg extract; IC50: 0.51 mg/mL) compared to the other two studied cultivars. Furthermore, the EY was enhanced by solvents richer in ethanol (50-75%), allowing obtaining extracts richer in TPC and TF with higher AA. Finally, it was shown that EY combined with bioactive data allowed a satisfactory principal component unsupervised differentiation of the pomegranate extracts according to the type of by-product used.This work was supported by the Foundation for Science and Technology (FCT, Portugal) through national funds to the research units CEB (UIDB/04469/2020), CERNAS (UIDB/00681/2020), and CIMO (UIDB/00690/2020) as well as to the Associate Laboratory SusTEC (LA/P/0007/2020). The European Regional Development Fund, under the Norte2020 Program funded BioTecNorte operation (NORTE-01-0145- FEDER-000004) and funded MobFood operation (LISBOA- 01-0247-FEDER-024524). Lara Campos acknowledges the research grants (CEB-BI-14-2019) and (FCT-IPC-i2A-CERNAS/ Escola de Verão/BI-01-08), and Luana Seixas acknowledges the research grant (FCT-IPC-i2A-CERNAS/Escola de Verão/BII-01-07), all provided by FCT.info:eu-repo/semantics/publishedVersio

Effect of malaxation temperature on olive oil chemical and sensory profiles and their evaluation using an electronic tongue

Olive oil is highly appreciated due to its nutritional and organoleptic characteristics. Olive oils rich in bioactive compounds can be obtained by optimizing the time and temperature of the malaxation process. In this sense, this study aimed investigating the effect of the malaxation temperature (22 to 34°C) on the olive oil's physicochemical and sensory quality and, in more detail, on the phenolic profile. So, virgin olive oils were produced (November 2018), using olives from cv. Cobrancosa. Furthermore, the possibility of using an electronic tongue, i.e., a multisensor potentiometric device, comprising non-specific lipid polymeric with cross-sensitivity sensor membranes, to monitor the malaxation temperature influence on the olive oil's quality and phenolic composition, was evaluated. For that, multivariate statistical tools were developed for discriminating the olive oils according to the malaxation conditions as well as to predict some key quality parameters, including the extinction coefficients (K232, K268 and |ΔK|), free acidity, oxidative stability, peroxide value, bitterness index, total phenols, phenolic composition and gustatory-retronasal positive attributes. The study aims to determine the best malaxation temperature as well as to assess the versatility of the electronic tongue as a single-run, fast and cost-effective analytical device for olive oils quality evaluation.This work was financially supported by Associate Laboratory LSRE-LCM - UID/EQU/50020/2019, strategic funding UID/BIO/04469/2019 -CEB and BioTecNorte operation (NORTE-01-0145-FEDER-000004), strategic project PEst-OE/AGR/UI0690/2014 -CIMO and by UID/QUI/50006/2019 funded by FCT/MCTES (PIDDAC) through national funds. I.M.G. Marx would also like to acknowledge FCT/MCTES for the Ph.D. grant number SFRH/BD/137283/2018.info:eu-repo/semantics/publishedVersio

Application of an electronic tongue as a single-run tool for olive oils’ total phenols and oxidative stability estimation

Olive oil quality can be enhanced during olive oil extraction, particularly by promoting the extraction of phenolic compounds extraction leading to the increase of the oxidative stability (OS). However, both total phenols content (TPC) and OS measurements (Folin-Ciocalteau spectrophotometric method and Rancimat, respectively) are time-consuming and expensive tasks, of difficult implementation in production lines. Thus, the present work studied the feasibility of using a potentiometric lab-made electronic tongue (E-tongue, Figure 1A), comprising non-specific lipid polymeric sensor membranes, coupled with multiple linear regression (MLR) models to predict TPC and an estimative of the OS of cv. Cobrançosa oils extracted at different malaxation temperatures (22 to 34 °C). For the potentiometric analysis, the oils’ polar phenol fraction was extracted with n-hexane and an aqueous methanolic solution (MeOH/H2O 80:20 v/v). The E-tongue-MLR models, based on sub-sets of 11 non-redundant sensors selected using the simulated annealing algorithm, allowed predicting (repeated K-folds-CV) the TPC (175<TPC<240 mg GAE/kg; RMSE=2.0±0.8 mg GAE/kg; R2=0.99±0.01) and, indirectly, to estimate the OS (11.5<OS<14.5 h; RMSE=0.08±0.07 h; R2=0.99±0.01), which values are directly related with the TPC. The satisfactory quantitative performance can be visualized in Figure 1B. In conclusion, the results showed that the E-tongue could be applied for quantifying TCP and predicting OS, both abovementioned shelf-life related parameters.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support by national funds FCT/MCTES to CIMO (UIDB/00690/2020), CEB (UIDB/04469/2020) and REQUIMTE-LAQV (UID/QUI/50006/2019)). I.M.G. Marx would also like to acknowledge FCT/MCTES for the Ph.D. grant number SFRH/BD/137283/2018. It is also acknowledge the national funding by FCT through the individual scientific employment program-contract with N. Rodriguesinfo:eu-repo/semantics/publishedVersio

The use of electronic nose as alternative non-destructive technique to discriminate flavored and unflavored olive oils

Cv. Arbequina extra virgin olive oils (EVOO) were flavored with cinnamon, garlic, and rosemary and characterized. Although flavoring significantly affected the physicochemical quality parameters, all oils fulfilled the legal thresholds for EVOO classification. Flavoring increased (20 to 40%) the total phenolic contents, whereas oxidative stability was dependent on the flavoring agent (a slight increase for rosemary and a decrease for cinnamon and garlic). Flavoring also had a significant impact on the sensory profiles. Unflavored oils, cinnamon, and garlic flavored oils had a fruity-ripe sensation while rosemary flavored oils were fruity-green oils. Fruit-related sensations, perceived in unflavored oils, disappeared with flavoring. Flavoring decreased the sweetness, enhanced the bitterness, and did not influence the pungency of the oils. According to the EU regulations, flavored oils cannot be commercialized as EVOO. Thus, to guarantee the legal labelling requirement and to meet the expectations of the market-specific consumers for differentiated olive oils, a lab-made electronic nose was applied. The device successfully discriminated unflavored from flavored oils and identified the type of flavoring agent (90 ± 10% of correct classifications for the repeated K-fold cross-validation method). Thus, the electronic nose could be used as a practical non-destructive preliminary classification tool for recognizing olive oils’ flavoring practice.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support by national funds FCT/MCTES to CIMO (UIDB/00690/2020) and to CEB (UIDB/04469/2020) units and to the Associate Laboratory SusTEC (LA/P/0007/2020), as well as to BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte 2020—Programa Operacional Regional do Norte. Nuno Rodrigues thanks to National funding by FCT—Foundation for Science and Technology, P.I., through the institutional scientific employment program-contractinfo:eu-repo/semantics/publishedVersio

Monitoring fructooligossacharides production using Aspergillus aculeatus by HPLC ELSD

Fructooligosaccharides (FOS) are present in plants and fruits at low concentrations, thus their extraction from natural sources may not be economically viable for a large scale industrial application. Therefore, FOS production by fermentation using fungi can be an alternative. In this work, FOS were produced using Aspergillus aculeatus at different sucrose initial concentrations (88 to 265 g/L) and at temperatures from 22 to 32ºC. FOS production was monitored by HPLC-ELSD, allowing to confirm that the initial sucrose concentration significantly influenced biomass growth (a maximum value of 16 ± 2 g was achieved) although it did not significantly affect the maximum FOS yield (amount of FOS produced per initial sucrose) obtained, which varied from 51 to 59 g/g) obtained, which varied from 51 to 59 g/g. Finally, the preliminary results enabled verifying that depending on the fermentation conditions, slightly different FOS production profiles were obtained (Figure 1), revealing differences in the individual FOS concentrations (i.e., 1-kestose, nystose and fructofuranosylnystose), which could be of interest since it has been reported that the beneficial health effects of FOS may depend on the relative FOS composition.This work was also financially supported by Project POCI-01–0145-FEDER-006984–Associate Laboratory LSRE-LCM, UID/AGR/00690/2013 –CIMO and UID/BIO/04469/2013 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.info:eu-repo/semantics/publishedVersio

Large‐scale impacts of selective logging on canopy tree beta‐diversity in the Brazilian Amazon

Selective logging is one of the largest drivers of tropical forest degradation. While logged forests often retain high alpha-diversity of tropical trees at local spatial scales, understanding how selective logging impacts tree beta-diversity and community composition across far larger spatial scales remains a key unresolved question. We leverage large datasets of more than 155,000 adult trees over 35 cm DBH covering 3100 ha of Amazonian rainforest to inform simulations of selective logging harvests across a gradient of logging intensity (0–40 m3 ha−1). These simulations incorporate real world price data, account for all forest damage throughout the harvest process and assume preferential harvest of the most valuable stems. We use the simulations to assess how selective logging affects canopy tree beta-diversity and composition across large spatial scales, whether nestedness or turnover of species best explains variation in communities across space, and how the spatial scale of sampling influences observed beta-diversity effects. Selective logging had minimal impacts on beta-diversity across the canopy tree community, but caused substantial subtractive heterogenization in community composition for larger trees, in particular very large trees over 110 cm DBH. Turnover is the dominant component of tree beta-diversity in unlogged and logged forests. Increasing the spatial grain of sampling reduced the observed importance of logging in explaining patterns of beta-diversity in very large tree communities. Synthesis and applications. Minimal impacts on tree beta-diversity across large spatial scales points towards the retention of substantial conservation value in logged tropical forests. Strong subtractive heterogenization in very large trees indicates the breakdown of broad scale patterns of composition with potential negative consequences for recruitment processes, fauna reliant upon emergent trees, and other ecosystem functions and services. Avoiding large-scale erosion of very large tree community composition in the Amazon requires stronger conservation policies, including enforced retention or maximum cutting diameters