Browsing by Author "Antunes, Paulo"
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- Análise química de mel para garantir conformidade de produtoPublication . Resende, Mafalda; Paulo, Luísa; Nunes, André; Antunes, Paulo
- Antioxidant and dual dose-dependent antigenotoxic and genotoxic properties of an ethanol extract of propolisPublication . Cruz, Maria Teresa; Antunes, Paulo; Paulo, Luísa; Ferreira, A.M.; Cunha, A.; Aguiar, C. Almeida; Oliveira, RuiPropolis is a resinous product made by honeybees from plant-derived materials, with high content ofpolyphenols associated to several beneficial bioactivities with potential use as a natural food additive forpreservation and as a functional food ingredient. A Portuguese propolis ethanol extract (C.EE) protectedSaccharomyces cerevisiaecells from loss of viability upon exposure to H2O2, both in co- and in pre-incubation experiments. Results obtained with the comet assay suggest that lower concentrations areantigenotoxic while at higher concentrations a genotoxic effect prevails, which correlates with thecytotoxicity of high concentrations of C.EE. Flow cytometry analysis with dichlorofluorescein indicatesthat C.EE induced intracellular antioxidant activityin vivo. Overall the results suggest that C.EE isantigenotoxic but is also toxic at higher concentrations. This dual effect could be explained by thepresence of compounds known to interfere with DNA synthesis and/or cell proliferation, such as caffeicacid phenethyl ester (CAPE) and chrysin, together with antioxidants, like kaempferol, pinobanksin andpinocembrin.
- Application of FTIR-ATR spectroscopy to the quantification of sugar in honeyPublication . Anjos, O.; Campos, Maria da Graça; Contreras Ruiz, Pablo; Antunes, PauloA Fourier transform infrared spectroscopic method with attenuated total reflectance (FTIR-ATR) and partial least squares (PLS) regression model for the prediction of sugar content in honey samples was calculated. Standards of trehalose, glucose, fructose, sucrose, melezitose, turanose and maltose were used to identify and quantify the individual sugar components in 63 honey samples by HPAEC-IPAD. Fructose and glucose are the highest sugars in honey with an average value of 36% and 26%, respectively. The 1stDer spectra with MSC or SLS in the wave number range from 1500 to 750cm(-1) provide the best calibration model with a r(2) of 86.60 and 86.01 with RPD of 2.6 and 2.55, respectively for fructose and glucose. For turanose and melezitose good models were also found. The FTIR-ATR showed to be a good methodology to quantify the main sugar content in honey and easily adapted to routine analysis.
- ATR-FTIR spectroscopy for determination of free acidity, electrical conductivity, ash and total polyphenol content in honeyPublication . Anjos, O.; Peres, Maria de Fátima; Antunes, Paulo; Rodrigues, José CarlosATR-FTIR spectroscopy for determination of free acidity, electrical conductivity, ash and total polyphenol content in honey.
- Caracterização da composição em açúcares do mel da região de Castelo BrancoPublication . Antunes, Paulo; Resende, Mafalda; Anjos, O.Caracterização da composição em açúcares do mel da região de Castelo Branco.
- Caracterização do perfil aromático de vinhos das castas Fonte Cal, Rufete, Touriga Nacional e Síria produzidos na região da Beira Interior por GC/MS.Publication . Pedro, Soraia; Queirós, Rodolfo; Antunes, Paulo; Anjos, O.O aroma do vinho é um dos factores mais importantes na determinação da sua qualidade e está relacionado com a aceitação ou rejeição deste produto pelos consumidores. As características do aroma são o resultado de complexas interacções entre diferentes factores, tais como a localização geográfica, a variedade de uva, a natureza do solo, o clima, a forma de condução da vinha, e as condições técnicas de processamento do vinho; ou seja o terroir. A análise química de compostos voláteis em vinho é usualmente efetuado por cromatografia gasosa com detetor de massas (GC/MS) com diferentes técnicas de extração prévias. Neste trabalho foi efetuada a avaliação do perfil de voláteis de quatro vinhos monovarietais das castas Fonte Cal, Rufete, Touriga Nacional e Síria, típicas da Região da Beira Interior, utilizando o método de HS-SPME que foi otimizado para este fim. O método incluiu a utilização do filme DVB/CAR/PDMS, 10 mL de amostra, temperatura de extração de 45°C, 3 g de NaCl e tempo de extração de 30 min. A análise foi efetuada num CG/MS (Agilent 7890A com Agilent 5975C), com desorção a 260ºC, utilizando-se uma coluna HP5MS, 30 m x 0,25 mm x 25 mm, com o seguinte programa de temperatura: 35ºC por 5 min, gradiente de 5 ºC/min até 240ºC, para separação dos compostos. Foi utilizado hélio como gás de arraste comfluxo de 1 ml min-1. Para otimização do método, a quantificação dos diferentes compostos em percentagem do total, foi utilizado hexanal como padrão interno. Nos vinhos analisados foram identificados 31 compostos voláteis com base na biblioteca do equipamento e 15 compostos para os quais não foi encontrada correspondência. Com base nos resultados obtidos da Análise de variância observaram-se diferenças significativas na composição aromática dos vinhos, evidenciando a tipicidade para cada casta. Estes serão comparados com os resultados da avaliação sensorial por painel de provadores, para correlacionar os diferentes compostos com os descritores do vinho. Em estudos futuros é necessário efetuar a validação destes resultados com os diferentes padrões de modo a quantificar os compostos já identificados e identificar os compostos para os quais não foram encontradas correspondência na biblioteca do GC/MS.
- Chemical composition of largemouth bass (Micropterus salmoides) filletPublication . Rodrigues, A.M.; Antunes, Paulo; Andrade, L.P.Largemouth bass (Micropterus salmoides) is a freshwater fish originating from the United States of America (USA). This specie was introduced in Portugal (Azores) in the end of the XIX Century. Like in the USA, largemouth bass is one of the most popular freshwater sports fish in Portugal and it is very important in regional cuisine, especially in the countryside. However, there’s a lack of information about the chemical composition of largemouth bass fillet. All eaten largemouth bass in Portugal are caught in large dams and small irrigation dams because there’s no largemouth bass aquaculture industry. The aim of this work was to evaluate the chemical composition of largemouth bass fillet collected in an irrigation reservoir (39º49’27.89’’ N; 07º26’57.92’’ W) located in the Central region of Portugal. Thirteen largemouth bass were collected (average weight 349.85g ±74.23; average length 27.22cm ±1.43; average K condition factor 1.71 ±0.14) and were frozen during seven days. The cutting carcasses and the filet chemical analyses (moisture, protein, fat and ash) took place in the laboratory. In the carcass, the average amounts of viscera, spine, head, skin and filet were, respectively, 8.52% (±1.41), 17.24% (±1.29), 23.06% (±1.85), 7.58% (±0.60) and 43.59% (±1.91). In the filet, the average amounts of moisture, protein, fat and ash were, respectively, 77.67% (±1.07), 18.46% (±0.83), 0.90% (±0.31) and 1.20% (±0.05). We concluded that largemouth bass has a good filet yield with very low fat and high level of protein contents. In fact, as far as we know, these are the first results of carcass and filet characterization of largemouth bass collected in Portugal.
- Composição em proteína, gordura e ácidos gordos de filetes de achigãs (Micropterus salmoides Lacépède, 1802) submetidos a três regimes alimentares diferentesPublication . Andrade, L.P.; Santos, C.; Resende, Mafalda; Antunes, Paulo; Rodrigues, A.M.Composição em proteína, gordura e ácidos gordos de filetes de achigãs (Micropterus salmoides Lacépède, 1802) submetidos a três regimes alimentares diferentes.
- Composição nutricional do filete de três espécies piscícolas de águas interiores com interesse gastronómicoPublication . Oliveira, Vítor Hugo; Antunes, Paulo; Resende, Mafalda; Andrade, L.P.; Rodrigues, A.M.Composição nutricional do filete de três espécies piscícolas de águas interiores com interesse gastronómico.
- Convective dehydration processing of peachPublication . Resende, Mafalda; Paulo, Luísa; Nunes, André; Silveira, Ana; Pintado, Cristina Miguel; Antunes, PauloDehydration of peach is an alternative to enhance storage stability, mínimize packaging requirement and reducing post-harvest cost without a sensorial and nutritional quality loss. Preservation of fruits through sun drying techniques is practiced in Cova da Beira (a Portuguese region that has a protected geographical indication for peach), as a homemade process without quality and safety control. The aim of this work was to prepare quality dehydrated products based on a convective drying process with low cost. This process has short drying time and controlled temperature that causes minimal damage to the product without added preservatives or sugar. The samples of ‘Baby Gold’ cultivar (Prunus persica) obtained from local producer were peeled, laminated and immediately dehydrated. Samples were stored in sealed plastic containers at 25°C for subsequent analysis. In the drying process were controlled forced convection air velocity of 1.25 to 1.50 m/s, air temperature between 45 and 75°C and drying time between 7 to 11 hours. During dehydration process temperature and fruit moisture were controlled. pH, acidity, soluble solids content (SSC) and mesophilic aerobic count were performed in fresh and dehydrated fruit. Dehydrated peach were similar to homemade products. Moisture was below 12%, without significant variation of SSC and acidity (on a dry basis). No deleterious effect occurred on peach mesophilic aerobic count, since a slight decrease was registered between fresh and dehydrated fruit.
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