http://hdl.handle.net/10366/4183 2026-04-22T22:12:18Z http://hdl.handle.net/10366/170781 [EN]In this work, three MP extracts obtained from Torulaspora delbrueckii were added to red wine, and the changes in phenolic composition, color, and astringency were evaluated by HPLC–DAD–ESI–MS, tristimulus colorimetry, and sensory analysis, respectively. The MP extracts modified wine phenolic composition differently depending on the type of MP. Moreover, two MP extracts were able to reduce wine astringency. The fact that the MP-treated wines showed an increased flavanol content suggests the formation of MP-flavanol aggregates that remain in solution. Furthermore, the formation of these aggregates may hinder the interaction of flavanols with salivary proteins in the mouth. The effect of these MPs might be associated with their larger size, which could influence their ability to bind flavanols and salivary proteins. However, one of the astringent-modulating MPs also produced a loss of color, highlighting the importance of assessing the overall impact of MPs on the organoleptic properties of wine. 2024-05-09T00:00:00Z http://hdl.handle.net/10366/169574 Tree tomato fruits from the yellow giant, giant purple and New Zealand purple cultivars, cultivated in Ecuador were analysed for their phenolic composition and antioxidant capacity. Twelve hydroxycinnamoyl derivatives and four anthocyanins (in the purple cultivars) were detected and identified. The hydroxycinnamoyl derivatives mostly derived from caffeic acid, being 3-O-caffeoylquinic acid and rosmarinic acid the majority compounds. Furthermore, various rosmarinic acid glucosides, caffeoyl glucoside, feruloyl glucoside and two ferulic acid dehydrodimers were tentatively identified. The presence of rosmarinic acid is particularly relevant as it constituted a majority phenolic compound in the four studied tree tomato cultivars and it had not been reported previously in this fruit. In the purple cultivars main anthocyanins were pelargonidin 3-O-rutinoside and delphinidin 3-O-rutinoside. The New Zealand purple cultivar was by far the richest sample in both hydroxycinnamates (421.6 mg/100 g dry pulp) and anthocyanins (168.9 mg/100 g dry pulp). Antioxidant capacity, as determined by FRAP, ABTS and ORAC assays, followed the same pattern as phenolic contents, with the New Zealand purple cultivar being the one with the highest and the yellow giant cultivar with the lowest values. 2016-01-01T00:00:00Z http://hdl.handle.net/10366/169572 BACKGROUND: Currently, there is growing interest in extracts derived from winery by-products because of their beneficial health properties, which are associated with the presence of bioactive compounds. In this paper, we have carried out the chemical characterization and in vitro colonic fermentation of four grape pomace (GP) extracts rich in polyphenols and dietary fibre. RESULT: Firstly, phenolic and dietary fibre composition of the GP extracts was determined. The highest individual phenolic concentrations corresponded to gallic and ellagic acids, followed by catechins and flavonols. The non-digestible fibre fraction ranged from 66% to 83% of the GP extracts, which indicated that they mainly contained non-digestible cell wall components. Secondly, when GP extracts were subjected to fermentation by faecal microbiota, a total of 16 bacterial phenolic metabolites were found in the fermented samples, confirming that polyphenols contained in the GP extracts were metabolized to different active metabolites by microbiota. In addition, the GP extracts tended to promote the growth of intestinal microbiota, although it was only significant for the Enterococcus group. CONCLUSION: These findings, together with other information available in the literature, support the high added value of products obtained from winery by-products. © 2016 Society of Chemical Industry. 2017-01-01T00:00:00Z http://hdl.handle.net/10366/169569 Flavonoids are phenolic compounds widely distributed in the human diet. Their intake has been associated with a decreased risk of different diseases such as cancer, immune dysfunction or coronary heart disease. However, the knowledge about the mechanisms behind their in vivo activity is limited and still under discussion. For years, their bioactivity was associated with the direct antioxidant and radical scavenging properties of phenolic compounds, but nowadays this assumption is unlikely to explain their putative health effects, or at least to be the only explanation for them. New hypotheses about possible mechanisms have been postulated, including the influence of the interaction of polyphenols and gut microbiota and also the possibility that flavonoids or their metabolites could modify gene expression or act as potential modulators of intracellular signaling cascades. This paper reviews all these topics, from the classical view as antioxidants in the context of the Oxidative Stress theory to the most recent tendencies related with the modulation of redox signaling pathways, modification of gene expression or interactions with the intestinal microbiota. The use of C. elegans as a model organism for the study of the molecular mechanisms involved in biological activity of flavonoids is also discussed. 2019-01-01T00:00:00Z http://hdl.handle.net/10366/169297 [EN]Colorimetric localized surface plasmon resonance (LSPR) as analytical response is applied for a wide number of chemical sensors and biosensors. However, the dependence of different factors, such as size distribution of nanoparticles (NPs), shape, dielectric environment, inter-particle distance and matrix, among others, can provide non-reliable results by UVevis spectrometry in complex matrices if NP assessment is not carried out, particularly at low levels of analyte concentrations. Miniaturized liquid chromatography, capillary (CapLC) and nano (NanoLC), coupled on line with in-tube solid phase microextraction (IT-SPME) is proposed for the first time for both, controlling suitability of used noble metal NP dispersions and developing plasmonic assays. Several capped noble NPs and target analytes were tested fromvariations in the chromatographic profiles obtained by using diode array detection. The IT-SPME step, which influenced the chromatographic fingerprint provided by noble NP dispersions, was studied by asymmetrical flow field flow fractionation (AF4) too. We monitored NP aggregation induced by interaction with several analytes like acids and spermine (SPN). Assessment of NPs was achieved in less than 10 min and it permitted to develop suitable plasmonic tests. Here, it was also demonstrated that these assays can be followed by IT-SPME-miniaturized LC-DAD and more sensitivity and selectivity than those provided by UVeVis spectrometry were achieved. Analysing urine samples to determine SPN as a cancer biomarker as a proof of concept is presented. 2021-08-01T00:00:00Z http://hdl.handle.net/10366/169295 [EN]The development of miniaturized systems has opened the possibility of the introduction of hand-portable liquid chromatography (LC), but LC has evolved slowly although it has significant potential for solving analytical challenges in various applications in situ or at-situ monitoring, due to their ability to perform measurements at the point of the potential analytical problem occurs. This chapter provides an overview of the current state of the art of portable LC technology and its context. The first LC reported as portable was the OB-4 or Milichrom, developed by Baram et al. in 1983, but this system is far away from the contemporary idea of portability although served as a basis for the later developed portable LCs. It was not until 2015, with notable advancements in pump, detectors, column technology, and batteries that a new wave of portable LCs emerged. A timeline with relevant portable LC contributions is given and their main features are described along the chapter. The Axcend Focus was the first commercialized capillary/nano portable LC. Sharma et al. in 2015 proposed a number of requirements that a LC system must achieve to be considered as portable and Rahimi et al. in 2020 developed a criteria to assess LC portability named BETTER criteria (portaBle fiEld Testing sTandard framework), which evaluates: the system cost, performance, robustness, operation time, portability, and weight. To date, portable LC systems meet some of the grade 2 and 3 criteria for almost all assessments. The grade 4 and 5 criteria are deemed a challenge to be met by next generation devices. Several studies have tested the capabilities of different pumping systems, with syringe pumps being the most popular options.Injectors have not presented a major obstacle when they come to adapting to portable equipment. The downscaling of LC has been closely related to the dimensions of the analytical column, particularly to its internal diameter, capillary packed and monolithic columns have been employed. On-column LED detection configurations, which do not make use of flow-cells eliminating the associated dead volumes were proposed. Electrochemical detectors were also used in portable LC. In the case of almost all portable LCs, which were homemade and were not commercialized, only one work for the most of them was published and then the number of real applications is scarce. New knowledge is necessary for advancing in portable LC. 2023-10-01T00:00:00Z http://hdl.handle.net/10366/169293 [EN]In this work, we have studied the main species involved in determining total dissolved nitrogen (TDN) in water samples for accommodating a variety of quantitation methodologies to portable instruments and with the goal to achieve in situ analysis. The rise of water eutrophication is becoming an ecological problem in the world and TDN contributes markedly to this. Traditionally the several forms of DN are measured in the laboratory using conventional instrumentation from grab samples, but their analysis in place and in real time is a current demand. Inorganic nitrogen: NO3 −, NO2 − and NH4 +, and organic nitrogen, such as amino nitrogen were tested here. For nitrate that presents native UV absorption suitable for direct water analysis, a portable optical fiber probe was compared with benchtop equipment and an in place analyzer. For nitrate, nitrite and ammonium, in situ solid devices that deliver reagents needed were tested and water color was measured by a smartphone coupled with a miniaturized optical fiber spectrometer and a miniaturized spectrometer or from images obtained and their RGB components. Amino nitrogen of some aromatic aminoacids with native fluorescence was followed by a portable optical fiber probe. Organic amino nitrogen and ammoniumwere determined by a portable luminometer and luminol supported in a measurement tube. Moreover, a portable miniaturized liquid chromatograph was shown suitable for monitoring priority nitrogen environmental pollutants. All options provided suitable results in comparison with lab estimations and were useful for evaluating if the legislation is fulfilled for the variety of tested waters. A discussion about the several portable options proposed for in place analysis, in function of the legislated determinations needed for each type of water was carried out. 2022-12-23T00:00:00Z http://hdl.handle.net/10366/169289 [EN]The greater and more widespread use of chemicals, either from industry or daily use, is leading to an increase in the discharge of these substances into the environment. Some of these are known to be hazardous to humans and the environment and are regulated, but there is a large and increasing number of substances which pose a potential risk even at low concentration and are not controlled. In this context, new techniques and methodologies are being developed to deal with this concern. Miniaturized liquid chromatography (LC) emerges as a greener and more sensitive alternative to conventional LC. Furthermore, advances in instrument miniaturization have made possible the development of portable LC instrumentation which may become a promising tool for in-situ monitoring. This work reviews the environmental applications of miniaturized LC over the last 15 years and discusses the different instrumentation, including off- and on-line pretreatment techniques, chromatographic conditions, and contributions to the environmental knowledge. 2024-06-20T00:00:00Z http://hdl.handle.net/10366/169285 [EN]The release of engineered nanoparticles (ENPs) into the environment is an emerging concern with significant implications for organism exposure due to the possible toxicity caused by these materials. Understanding the dissolution and transformation of silver nanoparticles (AgNPs) under dynamic flow conditions is critical, as these processes directly govern the mobility, persistence, and bioavailability of this material in natural aquatic systems, ultimately influencing its ecological risk and environmental impact. In this work, a methodology based on continuous- flow systems to assess the dissolution and transformation behavior of nanomaterials (NMs) under environmentally relevant conditions has been applied specifically to AgNPs. In this way, AgNPs nanopowder has been analyzed employing different environmental conditions (presence of oxygen, background electrolyte, types of buffers and NOM,). Results confirmed the expected dependency of AgNPs dissolution on the oxygen availability, corroborating previous batch assays. The evaluation of the AgNPs sulfidation in oxic and anoxic regimes were applied under different flow rates. AgNPs sulfidation is a complex process that takes place in two steps, oxidation followed by the AgS formation. Two different sulfide compounds 2025-11-14T00:00:00Z http://hdl.handle.net/10366/169200 [EN]In this paper, we propose a fast and reliable method for the determination of polyamines and related compounds in urine samples using flow injection analysis directly coupled to a triple quadrupole mass spectrometer, with the inclusion of a guard column (XBridge® C18 guard column; 2.1 × 10 mm, 3.5 µm) as a low-resolution fractioning step prior to MS analysis. The use of the guard column resulted in a sensitivity enhancement, a critical issue because of the low concentration of the target compounds found in urine samples. Moreover, it represents an interesting alternative to the use of other sample preparation techniques. Using this instrumental setup, each sample can be analyzed in 2.7 min, which makes this method appropriate for screening analysis. A method including a chromatographic separation step is also proposed, if confirmation of the results is required (samples with abnormal concentrations of the compounds). In this case, the total analysis time was 33.3 min. All the steps involved in sample preparation and instrumental conditions were optimized. In both methods, an ion-pairing reagent was added to the mobile phase and to the diluted sample. For the screening method, the limits of detection were found to be between 0.6 and 21 µg/L and the limits of quantification between 2.0 and 70 µg/L. Influence of the matrix was confirmed; thus quantification was performed using the one-point standard addition method and normalization to IS. Comparable results were obtained with the screening and the confirmatory methods when applied to urine samples of apparently healthy volunteers, showing that the proposed screening methodology is suitable for rapid and reliable analysis of polyamines and related compounds in these samples. 2020-06-01T00:00:00Z http://hdl.handle.net/10366/168910 [EN]Unbalanced wine astringency, caused by a gap between phenolic and technological grape maturities, is one of the consequences of the global climate change in the vitiviniculture. To resolve it, potential strategies are being currently used, like the addition of commercial yeast mannoproteins (MPs) to wines. In this work, the main interactions responsible for the wine astringent sensation, namely, interactions between human salivary proteins and wine flavanols have been studied by Dynamic Light Scattering (DLS) and liquid chromatography coupled to DAD and MS detectors (HPLC–DAD–MS), in presence or absence of two MPs with different saccharide/protein ratio. The results indicate that there are differences on the substrate specificity for each mannoprotein and that its action mechanism could change not only depending on the mannoprotein composition but also on the flavanol structure. MPs with elevated carbohydrate content could act thought the stabilization of soluble aggregates with human salivary proteins and flavanols, mainly non-galloylated flavanol oligomers, whereas MPs with higher protein percentage mostly could precipitate flavanols (mainly non-galloylated ones with low degree of polymerization) which partially prevents the formation of insoluble flavanol–salivary protein aggregates. 2021-01-01T00:00:00Z http://hdl.handle.net/10366/168909 [EN]It is known that interactions between wine flavanols and salivary proline-rich proteins (PRPs) are one of the main factors responsible for wine astringency. The addition of commercial yeast mannoproteins (MPs) to wines has been pointed to as a possible tool to modulate the excessive astringency due to a lack of phenolic maturity at harvest time that might occur as a consequence of global climate change. The aim of this work was to study by isothermal titration calorimetry and molecular dynamics simulation the molecular mechanisms by which mannoproteins could modulate astringency elicited by tannins and if it can be influenced by mannoprotein composition. Results obtained indicate that the MPs assayed had an important impact on astringency through the formation of ternary aggregates with different solubilities or by preventing the flavanol−PRP interaction by a competitive mechanism, although in a different strength, depending on the size and the compositional characteristic of the mannoprotein. 2020-01-01T00:00:00Z http://hdl.handle.net/10366/168908 [EN]Rosé wines, due to lower phenolic compounds and antioxidant content, are especially vulnerable to oxidation. Moreover, the valorization of winemaking byproducts is gaining interest, as it has the potential to reduce the environmental impact of wine production. For these reasons, the aim of this study was to investigate the effect of the addition of soluble polysaccharides, obtained from white grape pomace, on the phenolic oxidation of Syrah rosé wines. The soluble polysaccharides were extracted, characterized and added to the wines, which were periodically saturated with oxygen. The evolution of the phenolic composition and color parameters (CIELAB) was monitored by means of HPLC-DAD-MS and UV–vis spectrophotometry, respectively. The polysaccharide extract was mainly formed by homogalacturonans, type-II rhamnogalacturonans and polysaccharides rich in arabinose and galactose. The addition of this soluble extract seemed to promote the formation of acetaldehydemediated derived pigments in ros´e wines, with an increase in color intensity and sulfite bleaching resistance. During oxygenation, a protective trend against the degradation of flavanols and phenolic acids was also observed in the polysaccharide-added ros´e wines, which exhibited, at the end of this study, concentrations of these compounds that were 43.7 % and 11.5 % higher, respectively, than those in control samples. Therefore, these results suggest a protection of wine polyphenols, which reveals the potential use of these waste-derived extracts as a new oenological adjuvant for enhancing the phenolic and color stability of rosé wines. 2025-01-01T00:00:00Z http://hdl.handle.net/10366/168891 [EN]One of the most accepted mechanisms of astringency consists of the interaction between polyphenols and some specific salivary proteins. This work aims to obtain further insights into the mechanisms leading to a modulation of astringency elicited by polyphenols. The effect of the presence of different chemical species (present in food and beverages as food additives) on the polyphenol−protein interaction has been evaluated by means of techniques such as sodium dodecyl sulfate polyacrylamide gel electrophoresis and cell cultures using a cell-based model of the oral epithelium. Results obtained showed that several chemicals, particularly sodium carbonate, seem to inhibit polyphenol binding to salivary proteins and to oral epithelium. These results point out that polyphenol−saliva protein interactions can be affected by some food additives, which can help to better understand changes in astringency perception. 2020-01-01T00:00:00Z http://hdl.handle.net/10366/168887 [EN]In this work, three mannoprotein extracts were obtained from T. delbrueckii by enzymatic and chemical treatments. The obtained mannoprotein extracts showed important differences in their molecular weight distribution and monosaccharide composition, although no significant differences were found in their protein content. In order to evaluate the possible influence of mannoprotein characteristics in the interaction with flavanols, mannoprotein-flavanol interactions were studied by HPLC-DAD-MS and ITC. The results obtained indicate that the mannoprotein extracts were able to precipitate flavanols to a different extent. Furthermore, the degree of flavanol precipitation seemed not to be related to the affinity of the interaction but to the type of intermolecular forces. In this sense, a higher proportion of hydrogen bonding could favor a greater crosslinking between aggregates promoting flavanol precipitation. This, in turn, could be related to the MP characteristics since the presence of β-glucan moieties might have an effect on the formation of hydrogen bonds. 2024-01-01T00:00:00Z http://hdl.handle.net/10366/168736 [EN]This study presents an advanced analytical method for the simultaneous quantification of malondialdehyde (MDA), a biomarker of oxidative stress, and diphenyl phosphate (DPhP), a metabolite of the organophosphate flame retardant triphenyl phosphate (TPhP), in human urine. The method integrates hydrophilic interaction liquid chromatography (HILIC), a type of liquid chromatography suitable for polar compounds, for MDA separation, and an online restricted access material (RAM), a preconcentration column, for DPhP isolation, achieving high specificity and sensitivity. Validation with certified urine samples confirmed its robustness across diverse analyte concentrations and complex biological matrices. The optimized clean-up steps effectively minimized carryover, allowing for high-throughput analysis. Application to 72 urine samples revealed a significant positive correlation (ρ = 0.702, p-value = 1.9 × 10−7) between MDA and DPhP levels, supporting a potential link between oxidative stress and TPhP exposure. The subset analysis demonstrated a statistically significant moderate positive correlation in women (ρ = 0.622, p-value = 0.020), although this result should be interpreted with caution because of the limited sample size (N = 14). This method provides a powerful tool for biomonitoring oxidative stress and environmental contaminants, offering valuable insights into exposure-related health risks. 2025-07-17T00:00:00Z