Cláudia Nunes

Food Science, Biochemistry, Polymer Chemistry

PhD
28.29

Publications

  • [Show abstract] [Hide abstract]
    ABSTRACT: The impact of high hydrostatic pressure (HHP) treatments on the phenolic compounds composition of a red wine was studied after storage in order to evaluate the potential of this technology as an enological practice. Red wines pressurized at 500 and 600. MPa at 20. °C for 5 and 20. min, respectively, showed a lower content of monomeric anthocyanins (13 to 14%), phenolic acids (8 to 11%), and flavonols (14 to 19%) after 5. months of storage, when compared to the unpressurized wine. These results, together with the different degree of tannin polymerization and flavan-3-ol content in the pressurized wines led to propose an effect of HHP in the increase of polymerization and cleavage reactions of proanthocyanidins. The sensorial analysis of pressurized wines showed lower astringency, a higher intensity of cooked fruit aroma and lower intensity of fruity notes, when compared with the unpressurized wine. These effects are associated to those observed during wine aging. Industrial relevance: During the last decade, the use of high hydrostatic pressure (HHP) as a non-thermal technology for food preservation and modification has increased substantially. Recently, pressure treatments have shown to influence long term red wine physicochemical and sensorial characteristics, leading to aged wine-like characteristics. Therefore, the use of HHP technology to modify wine composition could benefit the wine industry, especially to improve wines with low aging potential. This work shows that HHP can be potentially used as enological practice, modulating the organoleptic properties of wine by decreasing astringency and increasing pleasant aromas. It seems possible to exploit commercially the production of young red wines with distinct characteristics using this technology, addressing the market and consumer demand.
    No preview · Article · Dec 2015 · Innovative Food Science & Emerging Technologies
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The impact of high hydrostatic pressure (HHP) treatments on volatile composition of sulphur dioxide-free wines during bottle storage was studied. For this purpose, white and red wines were produced without sulphur dioxide (SO2) and, at the end of the alcoholic fermentation, the wines were pressurised at 500MPa and 425MPa for 5min. Wine with 40ppm of SO2 and a wine without a preservation treatment were used as controls. More than 160 volatile compounds, distributed over 12 chemical groups, were identified in the wines by an advanced gas chromatography technique. The pressurised wines contained a higher content of furans, aldehydes, ketones, and acetals, compared with unpressurised wines after 9months of storage. The changes in the volatile composition indicate that HHP treatments accelerated the Maillard reaction, and alcohol and fatty acid oxidation, leading to wines with a volatile composition similar to those of faster aged and/or thermally treated wines. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Full-text · Article · Nov 2015 · Food Chemistry

  • No preview · Conference Paper · Oct 2015
  • Source

    Full-text · Article · Aug 2015 · Microscopy and Microanalysis
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Hollow multilayer nanocapsules were successfully prepared through layer-by-layer assembly of two bioactive polysaccharides, chitosan and fucoidan. The stepwise adsorption of 10 chitosan/fucoidan layers and the consequent formation of a multilayer film on polystyrene nanoparticles (used as templates) were followed through ζ-potential measurement and the removal of the polystyrene core was confirmed by FTIR analysis. The chitosan/fucoidan nanocapsules morphology and size were evaluated by SEM and TEM, which showed that after the core removal, the nanocapsules maintained their spherical shape and a decrease of size occurred. A cationic bioactive compound, poly-L-lysine (PLL), was chosen to evaluate the loading and release behaviour of the nanocapsules. The chitosan/fucoidan nanocapsules showed a good capacity for the encapsulation and loading of PLL, which shows to be influenced by the initial PLL concentration and the method of encapsulation used. The results of fitting the linear superimposition model to the experimental data of PLL release suggest an anomalous behaviour, with one main polymer relaxation. The PLL release was found to be pH-dependent: at pH 2 relaxation is the governing phenomenon and at pH 7 Fick's diffusion is the main mechanism of PLL release. Chitosan/fucoidan nanocapsules is a promising delivery system for water soluble bioactive compounds, such as PLL, showing a great potential of application in food and pharmaceutical industries
    Full-text · Article · Jan 2015 · Carbohydrate Polymers
  • [Show abstract] [Hide abstract]
    ABSTRACT: The characterization of several commercial dextrins and the analysis of the potential of dextrin derived hydrogels for biomedical applications were performed in this work. The structural characterization of dextrins allowed the determination of the polymerization and branching degrees, which ranged from 6 to 17 glucose residues and 2 to 13%, respectively. Tackidex, a medical grade dextrin was choosen for further characterization. The combination of hydrogel with a dextrin nanogel and urinary bladder matrix was achieved without compromising the mechanical properties or microstructure. The encapsulation of cells, preserving its viability, confirms the biocompatibility of the injectable hydrogels, which have therefore great potential for biomedical applications.
    No preview · Article · Dec 2014 · Carbohydrate Polymers
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Chitosan has been studied as a renewable polymer to form edible films allowing the incorporation of functional compounds. The aim of this work was to evaluate the effects in the chitosan films properties of the incorporation of grape pomace extracts: 0.15% of hot water extract (mainly polysaccharides), 0.15 and 0.3% of chloroform extract (wax), and 0.3 and 0.75% of n-hexane extract (oil). The evaluation of the surface morphology revealed that the films with the aqueous extract had the most homogeneous and smoother topography. The incorporation of higher proportion of wax and oil led to changes in mechanical properties of the films, namely lower resistance and stiffness. The chitosan-based films with 0.75% oil demonstrated a 75% decrease of solubility in water, due to their hydrophobicity, as confirmed by the contact angle and surface free energy measurements. The hydrophobic films showed higher antioxidant capacity in organic medium (ABTS and DPPH assays) whereas the most hydrophilic films showed an improvement in FRAP and reducing power assays. Therefore, all the chitosan-based films prepared by incorporation of these grape pomace extracts are promising for food shelf life extension.
    Full-text · Article · Nov 2014 · Carbohydrate Polymers
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Malus domestica Borkh. cv Bravo de Esmolfe is a typical Portuguese apple cultivar classified as Protected Designation and Origin(PDO). It is a traditional product produced under strict conditions and labelled with a specific law protected designation. This cultivar presents quite good sweetness and flavor. The monosaccharide composition of the pectic polysaccharides from this traditional apple is herein reported for the first time. Based on the molar ratios obtained from the sugar composition, the presumable pectin structure could be inferred. The cell-wall polysaccharides present in the alcohol-insoluble residue (AIR) of unpeeled BEapple were sequentially fractionated. In addition, pectic material was also extracted by citric acid treatment prior to heat extraction at acidic pH. The water soluble pectin, imidazole soluble pectin and sodium carbonate soluble pectin account for 44, 16 and 40 % of the AIR, respectively. The pectic polysaccharides extracted in the presence of citric acid had lower galacturonic acid content and higher neutral sugars content. The homogalacturonan (HG) and less-substituted rhamnogalacturonan (RG) domains are extracted first. Pectin treated with citric acid has been shown to contain more substituted polymers, especially RG-I. In addition, the relatively higher Xylose/Galacturonic acid ratio found in the citric acid extract demonstrates that the xylogalacturonan (XG) domain presumably is present in the pectic material of the unpeeled BE apple.
    Full-text · Article · Aug 2014 · Scientia Agricola
  • [Show abstract] [Hide abstract]
    ABSTRACT: Alterations in muscle mitochondrial bioenergetics during cancer cachexia were previously suggested; however, the underlying mechanisms are not known. So, the goal of this study was to evaluate mitochondrial phospholipid remodeling in cancer-related muscle wasting and its repercussions to respiratory chain activity and fiber susceptibility to apoptosis. An animal model of urothelial carcinoma induced by exposition to N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN) and characterized by significant body weight loss due to skeletal muscle mass decrease was used. Morphological evidences of muscle atrophy were associated to decreased respiratory chain activity and increased expression of mitochondrial UCP3, which altogether highlight the lower ability of wasted muscle to produce ATP. Lipidomic analysis of isolated mitochondria revealed a significant decrease of phosphatidic acid, phosphatidylglycerol and cardiolipin in BBN mitochondria, counteracted by increased phosphatidylcholine levels. Besides the impact on membrane fluidity, this phospholipid remodeling seems to justify, at least in part, the lower oxidative phosphorylation activity observed in mitochondria from wasted muscle and their increased susceptibility to apoptosis. Curiously, no evidences of lipid peroxidation were observed but proteins from BBN mitochondria, particularly the metabolic ones, seem more prone to carbonylation with the consequent implications in mitochondria functionality. In overall, data suggest that bladder cancer negatively impacts skeletal muscle activity specifically by affecting mitochondrial phospholipid dynamics and its interaction with proteins, ultimately leading to the dysfunction of this organelle. The regulation of phospholipid biosynthetic pathways might be seen as potential therapeutic targets for the management of cancer-related muscle wasting.
    No preview · Article · Jun 2014 · Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids
  • Source
    M. Vivas · C. Nunes · M. A. Coimbra · A. Solla
    [Show abstract] [Hide abstract]
    ABSTRACT: The antioxidant activity of Pinus pinaster seedlings originating from two contrasting maternal environments and inoculated with the fungal pathogen Fusarium circinatum was examined. The antioxidant activity related positively to the stem necrosis caused by the pathogen (p = 0.005), but this relationship differed significantly between maternal environments (p ≤ 0.002). Seedlings from mother trees grown under a favourable environment expressed a more variable antioxidant activity to F. circinatum than seedlings from mother trees grown in a less favourable environment. Antioxidant activity ranging from 80 to 100% resulted in shorter necrosis in seedlings from the favourable maternal environment than in seedlings from the unfavourable environment. Maternal effects caused shifts in the relationship between antioxidant activity and necrosis in offspring, and significantly modified the individual plant capacity for antioxidant response on pathogen penetration.
    Full-text · Article · Apr 2014 · Forest Pathology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Key message Carbohydrate differences in offspring as a consequence of maternal effects explain transgenerational tree-pathogen interactions. Abstract The expression of disease is increasingly recognised as being influenced by maternal effects, given that environmental conditions experienced by mother trees affect tolerance in offspring. It is hypothesised that plant carbohydrates could mediate transgenerational tree-pathogen interactions. The carbohydrate content of Pinus pinaster seedlings obtained from two contrasting maternal environments was studied and seedlings from the two environments were challenged with Fusarium circinatum. The representative mid-infrared spectra of samples in the range of the carbohydrates diagnosed higher proportion of methylesterified pectic polysaccharides and lower proportion of nonesterified pectic polysaccharides for inoculated than for control seedlings. Total carbohydrate content of seedlings from the unfavourable environment did not differ much from total carbohydrate content of seedlings from the favourable maternal environment. However, glucose was 13 % higher and uronic acids 11 % lower in seedlings from the favourable environment after inoculation in comparison to seedlings from the unfavourable maternal environment which had their carbohydrate contents unaltered after inoculation. It is concluded that plant carbohydrates mediate transgenerational tree-pathogen interactions.
    Full-text · Article · Apr 2014 · Trees
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The application of high hydrostatic pressure (HHP) in winemaking for substitution of the use of sulphur dioxide is still at a very early stage of development, since knowledge about the effect on physicochemical and sensorial characteristics of the wine during storage is very scarce. In this work, the evolution of colour, antioxidant activity and total phenolic compounds of SO2-free red wines treated by HHP and aged in bottles was followed for 12months. The pressurised wines were compared with wine samples prepared with addition of 40ppm of SO2 and without any of these two treatments. After 12months, the pressurised wines presented higher values of CIELab parameters (a(∗), b(∗), and L(∗)) and a lower monomeric anthocyanin content (45-61%) when compared to the unpressurised ones. The pressurised wines showed also a better global sensorial assessment, with the pressure treatments imparting aged-like characteristics to the wines. The wine deposits of pressurised wines had higher total phenolic content, namely proanthocyanidins (3- to 10-fold). The results demonstrate that HHP can influence long term red wine physicochemical and sensorial characteristics, hypothesised to be due to an increase of condensation reactions of phenolic compounds, forming compounds with higher degree of polymerisation that became insoluble in wine along storage.
    Full-text · Article · Dec 2013 · Food Chemistry
  • [Show abstract] [Hide abstract]
    ABSTRACT: Lipid homeostasis in liver is known to be altered with diabetes mellitus, ultimately leading to liver damage and related complications. The present work aimed to evaluate changes in the liver phospholipid profile after four months of uncontrolled hyperglycemia. Twenty Wistar rats were divided into two groups: control and streptozotocin-treated (T1DM). After four months, animals were sacrificed and morphological characterization of liver was performed and related with serum markers of hepatic damage. Lipid extracts were obtained from liver and phospholipid (PL) classes were quantified. Lipid molecular species were determined by LC-MS and LC-MS/MS, and fatty acids by GC-MS. Concomitantly with signs of hepatic damage we found variations in the relative amount of phospholipid classes in T1DM, characterized by a decrease in PLs with choline head group, and by an increase in the relative content of other PL classes. A remodeling in PL fatty acyl chains was observed in T1DM liver, with a similar pattern to all the PL classes, and consisting in the reduction of 16:0 and an increase of 18:0 and 18:2 acyl chains. The observed changes in T1DM lipid profile may contribute to the altered membrane properties underlying hepatic damage, worsening the metabolic alterations that characterize T1DM.
    No preview · Article · Aug 2013 · Archives of Biochemistry and Biophysics
  • [Show abstract] [Hide abstract]
    ABSTRACT: The impact of high hydrostatic pressure (HHP) treatments on physicochemical characteristics of sulphur dioxide-free white wines was studied during one year of bottle storage. For this purpose, a white wine was produced without the addition of sulphur dioxide (SO2) and was pressurized at two pressure conditions, 500 and 425 MPa, for 5 min at 20 °C. A wine with 40 ppm of SO2 and a wine with no preservation treatment were used as controls. Pressurized wines showed, after one year of storage, a more brownish colour (higher a* and b* values and lower L*) and a slightly lower antioxidant activity and total content of phenolic compounds compared to the unpressurized wines (wine with SO2 and wine without any treatment). These results, together with the lower content of free amino acids (e.g 87% less of serine) and higher content of furans (e.g 10 fold higher of 2-furfural), presented in the pressurized wines after nine months of storage, lead to propose an effect of HHP treatments in the acceleration of Maillard reactions occurring during the wine storage period. Sensorial analysis showed that the pressurized wines presented a higher cooked fruit aroma and lower fruity and floral aromas than the unpressurized wines.
    No preview · Article · Jul 2013 · Innovative Food Science & Emerging Technologies
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A reversed-phase high-performance liquid chromatographic method with fluorometric detection is proposed for the simultaneous determination of different classes of neutral sugars, such as hexoses (galactose, glucose and mannose), pentoses (arabinose and xylose), deoxy-hexoses (fucose and rhamnose), as well as acidic sugars (galacturonic and glucuronic acids). The separation is carried out on a hydrophilic end capped C18 column following a pre-column derivatization with p-aminobenzoic acid. The fluorometric detection of the derivatives has shown a strong dependency with the mobile phase pH. The performance of the proposed methodology was evaluated and the prerequisites of linearity (r-value > 0.999), precision (intra-day CV < 6 % and inter-day CV < 11 %) and recovery (between 77 ± 7 and 103 ± 3 %) were satisfied. To our knowledge, the obtained values of limit of detection for neutral sugars (within the range 6.1–28 μg L−1) are the lowest reported using this derivatizing agent. In order to better judge the methodology presented herein, neutral sugars of a pectin-rich orange extract were also analysed by the conventionally used GC-FID (gas-chromatography with flame ionization detector) method of alditol acetate derivatives. A statistical test (paired t test) has proved that no significant differences (α = 0.05) were observed between these two methods.
    Full-text · Article · Jul 2013 · Chromatographia
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We carboxymethylated ulvan, extracted from the green algae Ulva lactuca, and chitosan, extracted from Loligo forbesis squid-pen, yielding polysaccharides with an average degree of substitution of ∼98% (carboxymethyl ulvan, CMU) and ∼87% (carboxymethyl chitosan, N,O-CMC). The carboxymethylation was confirmed by FTIR and quantified by conductimetric titration and (1)H NMR. The average molecular weight increased with the carboxymethylation (chitosan: Mn 145→296 kDa and Mw 227→416 kDa; ulvan: Mn 139→261 kDa and Mw 368→640 kDa) indicating successful chemical modifications. Mixtures of the modified polysaccharides were tested in the formulation of polyacrylic acid-free glass-ionomer bone cements. Mechanical and in vitro bioactivity tests indicate that the inclusion of CMU in the cement formulation, i.e. 0.50:0.50 N,O-CMC:CMU, enhances its mechanical performance (compressive strength of 52.4 ± 8.0 MPa and modulus of 2.3 ± 0.3 GPa), generates non-cytotoxic cements and induces the diffusion of Ca and/or P-based moieties from the surface to the bulk of the cements.
    Full-text · Article · Jun 2013 · Acta biomaterialia
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Pitch canker disease is caused by Fusarium circinatum, a quarantine fungus in Europe with great virulence on several Pinus species. Susceptibility of Pinus pinaster to F. circinatum fungus has generated severe economic impact in nurseries of northern Spain. It is known that the maternal environment of P. pinaster significantly influences the resistance of their offspring to F. circinatum. To be protected from a wide variety of plant pathogens, plants have developed a complex set of defence mechanisms. Particularly, plant carbohydrates play an essential role during the pathogenesis of fungal diseases and plant antioxidant activity controls reactive oxygen species production during stress to protect themselves against oxidative damage. This study aims to evaluate the extent to which carbohydrates and antioxidant activity of P. pinaster originating from contrasting maternal environments could influence disease susceptibility of seedlings to F. circinatum. Seeds originating from the same clone but collected from two P. pinaster seed orchards located in Galicia (NW Spain) having identical genetic material and design but contrasting site qualities were selected. A total of 144 seeds, comprising 2 orchards × 3 ramets × 2 cones × 12 replicates were used. A randomised complete block design with seedlings growing in the same greenhouse was established. When plants were about 1.5 years old, seedlings were inoculated or not with F. circinatum. Four weeks after inoculation, necrosis length of inoculated and control seedlings were measured and all seedlings were harvested and samples removed. Samples consisting of a 3 cm stem segment below the inoculation point were immediately frozen in liquid N2 and stored at -80ºC until analysis. Changes in plant carbohydrates were assessed quantitatively by conventional techniques of gas chromatography and spectrophotometry, and qualitatively by Fourier transform-infrared (FT-IR) spectroscopy in association with chemometrics. Antioxidant activity was measured according to the method described in [1]. Total carbohydrate content was similar in seedlings from the unfavourable and favourable maternal environments and in non-inoculated and inoculated seedlings (P>0.05). However, seedlings from the favourable maternal environment significantly increased 13% their glucose content due to inoculation and reduced 11% their uronic acids content due to inoculation (P=0.045), while seedlings from the unfavourable maternal environment had their carbohydrate contents unaltered with the inoculation treatment. The antioxidant activity increased with the necrosis caused by the pathogen (P = 0.005) and differed between maternal environments (P < 0.001). Seedlings from the favourable maternal environment showed less antioxidant activity for a given lesion in comparison with seedlings from the unfavourable maternal environment. It is concluded that changes in carbohydrate content and antioxidant activity of P. pinaster seedlings after F. circinatum challenge were mediated by maternal effects, in the way that inoculated plants from the favourable maternal environment enhanced glucose and decreased uronic acids, and showed a more efficient antioxidant system in comparison with plants from the unfavourable maternal environment.
    Full-text · Conference Paper · May 2013
  • [Show abstract] [Hide abstract]
    ABSTRACT: The use of chitosan films has been limited due to their high degradability in aqueous acidic media. In order to produce chitosan films with high antioxidant activity and insoluble in acid solutions caffeic acid was grafted to chitosan by a radical mechanism using ammonium cerium (IV) nitrate (60mM). Genipin was used as cross-linker. This methodology originated films with 80% higher antioxidant activity than the pristine film. Also, these films only lost 11% of their mass upon seven days immersion into an aqueous solution at pH 3.5 under stirring. The films surface wettability (contact angle 105°), mechanical properties (68MPa of tensile strength and 4% of elongation at break), and thermal stability for temperatures lower than 300°C were not significantly influenced by the covalent linkage of caffeic acid and genipin to chitosan. Due to their characteristics, mainly higher antioxidant activity and lower solubility, these are promising materials to be used as active films.
    No preview · Article · Jan 2013
  • [Show abstract] [Hide abstract]
    ABSTRACT: 'Rainha Claudia Verde' is a regional cultivar of Prunus domestica L. well adapted to a specific region in the south of Portugal. In order to understand the postharvest behavior of this cultivar produced in different orchards, cell wall polysaccharides and cell wall calcium fruit content were studied during ripening in two consecutive years. During harvest period pectic fractions soluble in water, carbonate and KOH were prepared from alcohol-insoluble residue (AIR) of plums. Galacturonic and neutral sugars contents were measured during fruit ripening and fruit firmness was also evaluated. The calcium fruit level was determined in the AIR during harvest season as well as in dry matter. Fruit firmness was significantly higher in the second year and was probably related with calcium fruit content and pectic polysaccharides. There was a significant difference in calcium fruit content between orchards, and this might influence the overall fruit texture during the postharvest period. During fruit ripening water soluble pectic polysaccharides did not change significantly, which corresponded with the small decrease in tissue firmness. The occurrence in the supernatant of the cellulosic residue of highly branched polysaccharides might be the consequence of matrix material associated with microfibrilar phase. Depolymerization of the hemicellulosic fraction was not evident during plum ripening. The loss of fruit firmness is a consequence of many cellular events which are influenced by external factors. The knowledge of calcium content in the cell wall and the pectic polysaccharides could be of great importance to local farmers to predict fruit texture.
    No preview · Article · Jun 2012 · Acta horticulturae
  • [Show abstract] [Hide abstract]
    ABSTRACT: The study carried out in this work concerns the structural characterization of pectic polysaccharides from plum (Prunus domestica L.) and pear (Pyrus communis L.) cell walls and commercial pectic polysaccharides, obtained from Citrus. The α-(1 → 4)-d-galacturonic acid backbone was submitted to a selective hydrolysis with endo-polygalacturonase (EPG) and the fractions with low molecular weight (<1 kDa) obtained by size-exclusion chromatography were analysed by mass spectrometry using electrospray ionisation (ESI-MS). The ESI-MS spectra obtained revealed the presence of several [M+Na]+ ions of pectic oligosaccharides identified as belonging to different series, including oligosaccharides constituted only by galacturonic acid residues (GalAn, n = 1–5) and galacturonic acid residues substituted by pentose residues (GalA3Pentn, n = 1–2). Surprisingly, it was also observed the occurrence of galacturonic acid residues substituted by hexose residues (GalAnHexm, n = 2–4, m = 1–2). The fragmentation of the observed [M+Na]+ ions, obtained under ESI-MS/MS and MSn allowed to confirm the proposed structures constituent of these pectic oligosaccharides. Furthermore, the ESI-MSn spectra of the ions that could be identified as GalAnHexm (n = 2–4, m = 1–2) confirmed the presence of Hex or Hex2 residues linked to a GalA residue. Methylation analysis showed the presence, in all EPG treated samples, of terminally linked arabinose, terminally and 4-linked xylose, and terminally and 4-linked glucose. The occurrence of GalA substituted by Glc, and Glc-β-(1 → 4)–Glc are structural features that, as far as we know, have never been reported to occur in pectic polysaccharides.
    No preview · Article · Jan 2012 · Carbohydrate Polymers

22 Following View all

94 Followers View all