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Quantification of 3-deoxyglucosone (3DG) as an aging marker in natural and forced aged wines

Publication . Oliveira, Carla M.; Santos, Sónia A. O.; Silvestre, Armando J. D.; Barros, António S.; Ferreira, António César S.; Silva, Artur M. S.

The Maillard reaction product 3-deoxyglucosone (3DG) was quantified in wines, by high-performance liquid chromatography-mass spectrometry analysis after derivatization with ortho-phenylenediamine. Both sweet red Port wines and dry white wines were analysed during natural and forced aging. In natural aging, and for dry white wines, 3DG is negatively correlated to age (r = −0.939), while for sweet red Port wines, 3DG is positively correlated to age (r = 0.782). The same tendency was observed during a wine forced aging protocol. For a dry white wine, with higher levels of α-amino acids, 3DG is consumed (kconsumption 0.077–0.098 day−1) along the time protocol, while for a sweet red Port wine, with lower levels of α-amino acids, an accumulation of 3DG is observed with time (kformation 0.041–0.060 day−1). These results suggest that 3DG content can be used as an aging marker, as it has discriminated dry white and sweet red Port wines from different ages and cultivars. Analysis of wine-model solutions allowed verifying that the fructose content has a higher effect on 3DG formation than glucose, as well as that an increase on amino acids content does not lead to an increase of 3DG yields.

2016Journal article

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Oxygen vacancies, the optical band gap (Eg) and photocatalysis ofhydroxyapatite: Comparing modelling with measured data

Publication . Bystrov, V. S.; Piccirillo, C.; Tobaldi, D. M.; Castro, P. M. L.; Coutinho, J.; Kopyl, S.; Pullar, R.

Hydroxyapatite (Ca10(PO4)6(OH)2, HAp) is a calcium phosphate employed both in biomedicine and forenvironmental remediation. It is known that HAp can also be photocatalytic under UV light, probablydue to oxygen deficiencies, but the mechanism is unclear, and reported optical band gap energies varygreatly. For the first time we propose the mechanisms and precise kinds of vacancies which may causethe photocatalytic activity of HAp, and compare these theoretical data with our measured data on bothsamples of marine origin and commercial HAp powders. Density functional theory (DFT) (from firstprinciples calculations and Density of States (DOS) modelling) was used to calculate the optical bandgap energy (Eg) created by various possible oxygen vacancies in the HAp lattice: O from PO4, O fromOH, the loss of an entire OH group, or the simultaneous loss of O from PO4and an entire OH group. Themodelled values match the measured values very closely, suggesting that in non-photocatalytic HAp, ifany vacancies exist, they are O atoms from the OH group, resulting in a band gap of ∼5 eV in the UVCregion (not present in solar light at the Earth’s surface). However, in photocatalytic HAp, reduction fromthe combustion of an organic component at 1000◦C led to oxygen deficiency in the phosphate groups,probably in the O15 position, giving an Egof ∼3.45 eV, in the UVA region (present in sunlight). HeatingHAp with no organic component to 1200◦C also led to vacancies, of both an entire OH group and oxygenfrom PO4groups, which led to an intermediate Egvalue of ∼4 eV, on the boundary of the UVA-UVB regions.Absorption peaks were also predicted in the visible-light region with some types of vacancy.

2016Journal article

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Effects of Cu, Zn and Cu-Zn addition on the microstructure and antibacterial and photocatalytic functional properties of Cu-Zn modified TiO2 nano-heterostructures

Publication . Tobaldi, D. M.; Piccirillo, C.; Rozman, N.; Pullar, R. C.; Seabra, M. P.; Škapin, A. Sever; Castro, Paula M. L.; Labrincha, J. A.

Titanium dioxide (TiO2) is well established as one of the most common photocatalysts used for many environmental, anti-pollution and antibacterial applications. However, in this work, novel photocatalytic TiO2 nanopowders were modified with additions of 1 mol% copper, zinc or copper + zinc (with various Cu: Zn ratios). These were prepared via a green sol–gel route and thermally treated at 450 C. For the first time, a direct comparison of the effects of these two modifying agents was performed, both as single and co-substitution. The compounds were thoroughly characterised by means of advanced X-ray diffraction (Whole Powder Pattern Modelling, WPPM) and spectroscopic methods (Raman and UV–vis). For functional properties, the photocatalytic activity in the gas-solid phase (nitrous oxides (NOx) and isopropanol degradation (VOCs)) was tested under UV and visible light, and antibacterial activity against Gram positive and Gram negative bacterial strains was also investigated. Neither copper nor zinc entered into the TiO2 structure, but nucleated as oxides at the surface of titania nanoparticles, thus creating a nano-heterojunction between the semiconductor materials; this also retarded the anatase-to-rutile phase transition. When comparing and contrasting their functional properties, it was found that Zn modification gave greater photocatalytic activity than that with Cu. On the contrary, for antibacterial activity, copper was shown to be a better additive. Co-modification with both metals did not improve the antibacterial behaviour, but did lead to an increase in photocatalytic activity in some cases.

2016Journal article

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Antimicrobial activity of pomegranate peel extracts performed by high pressure and enzymatic assisted extraction

Publication . Alexandre, Elisabete M. C.; Silva, Sara; Santos, Sónia A. O.; Silvestre, Armando J. D.; Duarte, Maria F.; Saraiva, Jorge A.; Pintado, Manuela

This study aimed to assess the effect of high pressure (300 and 600 MPa) and enzymatic extraction (pectinase and cellulase) on the phenolic compounds profile, antioxidant capacity and antimicrobial activity of extracts from pomegranate by-products. Antimicrobial activity against eight different strains of pathogenic and contaminant bacteria and against five beneficial bacteria including Lactobacillus and Bifidobacterium strains were determined. The maximum level of total phenolic content, as well as antioxidant capacity were observed at 300 MPa, however enzymatic extraction did not improve the extraction yields. Punicalagin isomers and bis-hexahydroxydiphenoyl-glucoside isomer were the most abundant phenolic compounds found in the extracts. All pomegranate peel extracts demonstrated selective antimicrobial activity against all pathogenic bacteria without affecting beneficial ones. Pressurized extracts presented lower minimum inhibitory concentration against Bacillus cereus and Pseudomonas aeruginosa and lower minimum bactericidal concentration against B. cereus, while, enzymatic extracts presented lower minimum bactericidal concentration for Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus and Listeria monocytogenes. Principal component analyses reveled that antioxidant activity and phenolic compounds content were strongly related with antimicrobial activity. Pomegranate peels extracts obtained by high pressure extraction could so be used as a source of high added-value bioactive compounds for antioxidant and antimicrobial applications.

2019Journal article

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BIONANOSCULP, an ongoing project in biotechnology applications for preventive conservation of outdoor sculptures

Publication . Moreira, P R; Silva, N; Pullar, R. C.; Ben-Arfa, B. A. E.; Abreu, J. G.; Henriques, F.; Pintado, M M E; Vieira, E

The objective of this paper is the presentation of the research strategies adopted and results of the ongoing BIONANOSCULP research project that is aiming to develop solutions in the area of sustainable nanomaterials, which are non-invasive and high-performance in their preventive conservation approach. An integrated methodology was designed as a holistic strategy to the characterisation of the microbiota present on the surface of public outdoor sculptures. Gathering objective data in the characterization of the surface microbiota of public outdoor sculptures is important, in order to design strategies for the preventive conservation of these objects that make use of biotechnology innovative coatings. Such is one of the objectives of the project BIONANOSCULP. Methodologies applied include conservation reports, surface sampling methodologies using gels, 3D modeling, SEM, flow cytometry and metagenomics. The project is already significantly contributing to create a bridge between the experts from different areas: the skills of biotechnologists, microbiologists, materials scientists, art historians and conservators-restorers to assess the state of conservation, biodeterioration and biocontamination of a selected number of sculptures, and to design the appropriate materials to pursue preventive conservation through coatings with anti-microbial activities.

2018Conference object

Open access