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A hybrid electronic tongue for direct classification of baby liquid foods with or without gluten IPB - Escola Superior Agrária
Peres, António M.; Dias, L.G.; Veloso, Ana C.; Sousa, Mara E.B.C.; Machado, Adélio A.S.C..
Tipo: ConferenceObject
Ano: 2011 URL: http://hdl.handle.net/10198/6399
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A hybrid electronic tongue for direct classification of baby liquid foods with or without gluten IPB - Escola Superior Agrária
Peres, António M.; Dias, L.G.; Veloso, Ana C.; Sousa, Mara E.B.C.; Machado, Adélio A.S.C..
People suffering from celiac disease are gluten intolerant and inadvertent ingestion of gluten proteins must be avoided. Several techniques have been proposed to detect/quantify gluten proteins in foodstuffs: immunochemical methods, mass tandem spectrometry and polymerase chain reaction as well as gluten sensors [1]. Recently, a potentiometric electronic tongue (ET) with lipo/polymeric membranes has been used to detect gliadins, which are gluten proteins, in foodstuffs [2]. However, the use of these techniques requires the previous extraction of gluten proteins. This step can be a possible drawback since it is not possible to guarantee that the extraction has a 100% yield since the protein types overlap in solubility and extractability [3]. In this work,...
Tipo: ConferenceObject
Ano: 2011 URL: http://hdl.handle.net/10198/6400
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A modified UNIFAC model for the calculation of thermodynamic properties of aqueous and non-aqueous solutions containing sugars IPB - Escola Superior Agrária
Peres, António M.; Macedo, Eugénia A..
A UNIFAC based model is proposed to describe experimental thermodynamic properties of aqueous and non-aqueous solutions containing common sugars, e.g., D-glucose, D-fructose and sucrose. A new group 'OHring' is introduced due to proximity effects. New temperature-independent UNIFAC interaction parameters are estimated based on the binary data available for both D-glucose and D-fructose and only on the solubility data for sucrose. The UNIFAC model used in this work is able to accurately predict the water activity, boiling temperature and freezing point of aqueous sucrose solutions. However, the predictions of the osmotic coefficients for the sucrose/water system present relative deviations up to 9%. Satisfactory predictions of vapor-liquid and solid-liquid...
Tipo: Article Palavras-chave: UNIFAC; Solid-liquid equilibria; Vapor-liquid equilibria; Water-Ethanol-Methanol; Carbohydrates.
Ano: 1997 URL: http://hdl.handle.net/10198/3223
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Adsorption equilibrium of fructose, glucose and sucrose for cationic resins in the sodium and potassium form IPB - Escola Superior Agrária
Nobre, Clarisse; Santos, M.J.; Dominguez, Ana; Torres, Duarte; Peres, António M.; Rocha, Isabel; Ferreira, Eugénio C.; Rodrigues, Lígia R.; Teixeira, José.
Separation of glucose from mixtures of fructose and sucrose in molasses is a major challenge in industrial sugar chromatographic separations. The efficiency of a chromatographic process is largely dependent on the adsorbent used. Sulfonated poly(styrene-co-divinylbenzene) (PS-DVB) ion exchange resins are the most frequently used for sugars separation, generally in a cationic form. The cation will complex with the hydroxyl group of the sugar leading to a selective adsorption according to the orientation of the hydroxyl group. Thus, the conformation of the sugar determines its relative affinity for the resin and its distribution coefficient. Consequently, fructose forms the more stable sugar-cation complex being preferentially adsorbed in the resin followed...
Tipo: ConferenceObject
Ano: 2009 URL: http://hdl.handle.net/10198/3778
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An electronic tongue for beer differentiation IPB - Escola Superior Agrária
Dias, L.G.; Peres, António M.; Barcelos, T.P.; Morais, Jorge Sá; Machado, A.A.S.C..
In this work an electronic tongue, based on a potentiometric solid-state mufti-sensor array, with 36 polymeric membranes, was built for developing an analytical tool to apply in process monitoring and quality control. As a first approach, this tool was applied together with a supervised pattern recognition tool to semi-quantitatively differentiate beers with different alcoholic levels.
Tipo: ConferenceObject
Ano: 2009 URL: http://hdl.handle.net/10198/3026
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An electronic tongue for gliadins semi-quantitative detection in foodstuffs IPB - Escola Superior Agrária
Peres, António M.; Dias, L.G.; Veloso, Ana C.A.; Meirinho, Sofia G.; Morais, Jorge Sá; Machado, A.A.S.C..
An all-solid-state potentiometric electronic tongue with 36 polymeric membranes has been used for the first time to detect gliadins, which are primarily responsible for gluten intolerance in people suffering from celiac disease. A linear discriminant model, based on the signals of 11 polymeric membranes, selected from the 36 above using a stepwise procedure, was used to semi-quantitatively classify samples of a “Gluten-free” foodstuff (baby milked flour), previously contaminated with known amounts of gliadins (<10, 20–50 or >50 mg/kg), as “Gluten-free”, “Low-Gluten content” or “Gluten-containing”. For this food matrix, the device had sensitivity towards gliadins of 1–2 mg/kg and overall sensitivity and specificity of 77% and 78%, respectively....
Tipo: Article Palavras-chave: Gliadins; Electronic tongue; Linear discriminant analysis; Celiac disease; Protein analysis.
Ano: 2011 URL: http://hdl.handle.net/10198/3819
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An electronic tongue for honey classification IPB - Escola Superior Agrária
Dias, L.G.; Peres, António M.; Vilas-Boas, Miguel; Rocha, Maria A.; Estevinho, Leticia M.; Machado, A.A.S.C..
An electronic tongue system was developed based on 20 all-solid-state potentiometric sensors and chemometric data processing, with polymeric membranes applied on solid conducting silver-epoxy supports and a Ag=AgCl reference electrode. The sensor array was applied to 52 commercial honey samples obtained randomly from different regions of Portugal. These samples were analysed independently for their pollen profiles by biological techniques and the data collected with the tongue were evaluated for discrimination of the samples with multivariate statistical methods (principal component analysis and linear discriminant analysis), to investigate whether the device may provide an analytical alternative for classification of honey samples with respect to pollen...
Tipo: Article Palavras-chave: Honey; Pollen; Electronic tongue; Multivariate analysis.
Ano: 2008 URL: http://hdl.handle.net/10198/1027
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An electronic tongue for juice level evaluation in non-alcoholic beverages IPB - Escola Superior Agrária
Peres, António M.; Dias, L.G.; Barcelos, T.P.; Morais, Jorge Sá; Machado, A.A.S.C..
An electronic tongue with 36 cross-sensibility polymeric membranes was built and used for semi-quantitative analysis of beverages. The objective was to differentiate 4 non-alcoholic beverage groups with different added fruit juice contents: higher than 30%, between 14%-30%, 5%-10% and 0.1%-2%. A set of 16 Portuguese beverages (4 for each group), purchased in commercial supermarkets, was analyzed and the respective signal profiles recorded by the electronic tongue device. The data obtained were treated by stepwise linear discriminant analysis, allowing a 100% overall correct classification for the original grouped cases and a 93.8% for the “leaving one-out” cross-validation procedure
Tipo: Article Palavras-chave: Discriminant analysis; Electronic tongue; Fruit juice level; Non-alcoholic beverages; Polymeric membranes.
Ano: 2009 URL: http://hdl.handle.net/10198/2232
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An electronic tongue for juice level evaluation in non-alcoholic beverages IPB - Escola Superior Agrária
Peres, António M.; Dias, L.G.; Barcelos, T.P.; Morais, Jorge Sá; Machado, A.A.S.C..
An electronic tongue with 36 cross-sensibility polymeric membranes was built and applied for qualitative beverage analysis.
Tipo: ConferenceObject
Ano: 2009 URL: http://hdl.handle.net/10198/3028
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An electronic tongue taste evaluation: identification of goat milk adulteration with bovine milk IPB - Escola Superior Agrária
Dias, L.G.; Peres, António M.; Veloso, Ana C.A.; Reis, F.S.; Vilas-Boas, Miguel; Machado, A.A.S.C..
An electronic tongue with 36 cross-sensibility sensors was built allowing a successful recognition of the five basic taste standards, showing high sensibility to acid, salty and umami taste substances and lower performance to bitter and sweet tastes. The taste recognition capability was afterwards tested in the detection of goat milk adulteration with bovine milk, which is a problem for the dairy industry. This new methodology is an alternative to the classical analyticalmethods used to detect caprine milk adulterations with bovine milk, being a simpler, faster and economical procedure. The different signal profiles recorded by the e-tongue device together with linear discriminant analysis allowed the implementation of a model that could distinguish...
Tipo: Article Palavras-chave: Electronic tongue; Taste standards; Milk adulteration; Cow milk; Goat milk; Principal component analysis; Linear discriminant analysis.
Ano: 2009 URL: http://hdl.handle.net/10198/1029
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Aplicação de uma língua electrónica na classificação de méis monoflorais IPB - Escola Superior Agrária
Morais, L.; Dias, L.G.; Peres, António M.; Rocha, A.C.; Estevinho, Leticia M.; Machado, A.A.S.C..
Analisou-se o perfil polínico de 51 amostras de mel nacional. Os pólens mais frequentes no mel são originários das plantas dos géneros Lavandula, Cistus, Echium, Erica, Castanea, Thymus, Prunus, Cytisus, Carduus, Trifolium e Citrus. Considerando a classificação de mel monofloral de Lavandula (pólen predominante superior a 15%), de Erica e de Echium (pólen predominante superior a 45%) seleccionaram-se 38 méis monoflorais: 18, 9 e 11 destes méis foram classificados como méis monoflorais de Lavandula, Erica e Echium, respectivamente. Contudo há méis que podem ser classificados como mel monofloral de dois géneros de pólen (Lavandula-Echium, Erica-Lavandula, Echium-Lavandula). Os méis monoflorais foram analisados com um sistema de multi-sensores...
Tipo: Article Palavras-chave: Mel; Pólen; Língua electrónica; Análise multivariada.
Ano: 2007 URL: http://hdl.handle.net/10198/3031
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Application of an electronic tongue to detect gliadins in gluten-free foods IPB - Escola Superior Agrária
Peres, António M.; Dias, L.G.; Veloso, Ana C.A.; Meirinho, S.G.; Morais, Jorge; Machado, A.A.S.C..
Celiac disease is an autoimmune-mediated disorder triggered in genetically susceptible individuals by the ingestion of some gluten proteins, namely gliadins. To prevent inadvertent gluten consumption, the Commission Regulation (EC) N°41/2009 will implement labeling foods as ‘gluten-free” or “low-gluten content.
Tipo: ConferenceObject
Ano: 2010 URL: http://hdl.handle.net/10198/3020
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Assessment of goat fat depots using ultrasound technology and multiple multivariate prediction models IPB - Escola Superior Agrária
Peres, António M.; Dias, L.G.; Joy, M.; Teixeira, A..
Assessment of fat depots for several goat body parts is an expensive and time-consuming task requiring a trained technician. Therefore, the establishment of models to predict fat depots based on data requiring simpler and easier procedures, such as ultrasound measurements, that could be carried out in vivo, would be a major advantage. An interesting alternative to the use of multiple linear regression models is the use of partial least squares or artificial neural network models because they allow the establishment of one model to simultaneously predict different fat depots of interest. In this work, the applicability of these models to simultaneously predict 7 goat fat depots (subcutaneous fat, intermuscular fat, total carcass fat, omental fat, kidney and...
Tipo: Article Palavras-chave: Artificial neural network; Carcass fat composition prediction; Goat; Partial least squares; Ultrasound technology.
Ano: 2010 URL: http://hdl.handle.net/10198/5197
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Assessment of physiological conditions in e. Coli fermentations by epifluorescent microscopy and image analysis IPB - Escola Superior Agrária
Carneiro, Sónia; Amaral, António L.; Veloso, Ana C.A.; Dias, Teresa; Peres, António M.; Ferreira, Eugénio C.; Rocha, Isabel.
The development of monitoring methods for assessing the physiological state of microorganisms during recombinant fermentation processes has been encouraged by the need to evaluate the influence of processing conditions in recombinant protein production. In this work, a technique based on microscopy and image analysis was developed that allows the simultaneous quantification of parameters associated with viability and fluorescent protein production in recombinant Escherichia coli fermentations. Images obtained from light microscopy with phase contrast are used to assess the total number of cells in a given sample and, from epifluorescence microscopy, both protein producing and injured cells are evaluated using two different fluorochromes: propidium iodide...
Tipo: Article Palavras-chave: Recombinant E. coli fermentations; Epifluorescent microscopy; Physiology assessment; Image analysis.
Ano: 2009 URL: http://hdl.handle.net/10198/3231
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Autenticidade de queijos tradicionais: um factor de qualidade IPB - Escola Superior Agrária
Peres, António M.; Ramalhosa, Elsa; Veloso, Ana C.A..
O crescente interesse e consumo de produtos lácteos regionais como os queijos de Denominação de Origem Protegida (DOP), torna Indispensável o desenvolvimento e aperfeiçoamento de técnicas analíticas que permitam assegurar a sua autenticidade e controlar eventuais fraudes. De entre os queijos DOP, 0 Queijo Terrincho e o queijo Transmontano são, de um ponto de vista produtivo, os que apresentam maior relevância económica no Nordeste de Portugal.
Tipo: ConferenceObject Palavras-chave: Queijo; Autenticidade.
Ano: 2005 URL: http://hdl.handle.net/10198/3666
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Avaliação simultânea de depósitos adiposos em caprinos, recorrendo a ultrasonografia em tempo real (UTR) em associação com modelos de redes neuronais (ANN) IPB - Escola Superior Agrária
Teixeira, A.; Dias, L.G.; Pereira, Etelvina; Peres, António M..
Recentemente foram realizados estudos para melhorar a previsão da composição corporal ou carcaças de caprinos. Com a perspectiva de usar um modelo exclusivo para estimar a composição corporal, baseado em um número reduzido de estimadores, foi proposto um modelo usando redes neurais artificiais. Neste sentido o principal objectivo do presente trabalho será demonstrar a necessidade de organizar uma rede mundial para construir um grande banco de dados, de composição corporal e carcaça, para as raças mais importantes de caprinos em graus diferentes graus de maturidade, que proporcione o desenvolvimento de modelos gerais, robustos e fiáveis, bem como para implementar uma técnica on-line moderna e objectiva para a avaliação e classificação comercial.
Tipo: ConferenceObject
Ano: 2010 URL: http://hdl.handle.net/10198/5236
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Casein breakdown in terrincho ovine cheese: comparison with bovine cheese and with bovine/ovine cheeses IPB - Escola Superior Agrária
Ferreira, Isabel M.P.L.V.O.; Veiros, C.; Pinho, Olívia; Veloso, Ana C.A.; Peres, António M.; Mendonça, Álvaro.
Terrincho cheese is an uncooked, pressed cheese made from raw whole ovine milk from the “Churra da Terra Quente” breed. It requires a minimum ripening time of 30 d. A detailed evaluation of the effect of ripening time on the breakdown of the casein fractions, along with the formation of major breakdown products of casein hydrolysis, was monitored by HPLC to contribute to a more complete characterization of this product. In 30-d-old cheeses, only 20% of αS1-casein remained intact; the β-casein fraction was more resistant to hydrolysis. The ripening time of Terrincho cheese can be predicted using 2 variables of normalized peak areas of αS1-casein and αS1-I peptide, and a constant; the estimation error is 2.5 d. The pH 4.3-insoluble fraction of Terrincho and...
Tipo: Article Palavras-chave: Cheese; Proteolysis; Caseins; High performance liquid chromatography.
Ano: 2006 URL: http://hdl.handle.net/10198/3229
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Characterization of phenolic compounds of OMW: toxicity and degrability by yeasts IPB - Escola Superior Agrária
Gonçalves, Cristiana; Ferreira, João P.; Lopes, Marlene; Falcão, Soraia; Peres, António M.; Cardoso, Susana M.; Belo, Isabel.
The olive oil extraction, performed by the 3-phases process, results on a large amount of an effluent, usually known as Olive Mill Wastewater (OMW). It is mainly produced in the Mediterranean area, with the exception of Spain that is one of the major producers but mostly use the 2-phases process. OMW represents a major environmental problem due to its high organic content, being characterized by a strong acidic smell and an intensive brown to dark color due to the presence of biodegradable, recalcitrant and biostatic compounds. OMW phytotoxicity can be attributed to the phenolic compounds (Lanciotti et al, 2005). Owing to their instability, OMW phenols tend to polymerise during storage into condensed high-molecular-weight polymers that are difficult to...
Tipo: ConferenceObject Palavras-chave: Lipolytic yeasts; Phenol compounds; Lipase; OMW.
Ano: 2008 URL: http://hdl.handle.net/10198/5769
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Chemometric classification of several olive cultivars from Trás-os-Montes region (Northeast of Portugal) using artificial neural networks. IPB - Escola Superior Agrária
Peres, António M.; Baptista, Paula; Malheiro, R.; Dias, L.G.; Bento, Albino; Pereira, J.A..
This work aimed to use artificial neural networks for fruit classification according to olive cultivar, as a tool to guarantee varietal authenticity. So, 70 samples, each one containing, in general, 40 olives, belonging to the six most representative olive cultivars of Trás-os-Montes region (Cobrançosa, Cordovil, Madural, Negrinha de Freixo, Santulhana and Verdeal Transmontana) were collected in different groves and during four crop years. Five quantitative morphological parameters were evaluated for each fruit and endocarp, respectively. In total, ten biometrical parameters were used together with a multilayer perceptron artificial neural network allowing the implementation of a classification model. Its performance was compared with that obtained using...
Tipo: Article Palavras-chave: Olea europaea L.; Artificial neural networks; Linear discriminant analysis; Authenticity; Cultivars; Protected designation of origin.
Ano: 2011 URL: http://hdl.handle.net/10198/3125
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Comparison of adsorption equilibrium of fructose, glucose and sucrose on potassium gel-type and macroporous sodium ion-exchange resins IPB - Escola Superior Agrária
Nobre, Clarisse; Santos, M.J.; Dominguez, Ana; Torres, Duarte; Rocha, Orlando; Peres, António M.; Rocha, Isabel; Ferreira, Eugénio C.; Teixeira, José A.; Rodrigues, Lígia R..
Adsorption equilibrium of fructose, glucose and sucrose was evaluated on sulfonated poly(styrene-codivinylbenzene) cation-exchange resins. Two types of resins were used: potassium (K+) gel-type and sodium (Na+) macroporous resins. Influence of the cation and effect of the resin structure on adsorption were studied. The adsorption isotherms were determined by the static method in batch mode for monocomponent and multi-component sugar mixtures, at 25 and 40 ◦C, in a range of concentrations between 5 and 250 g L−1. All adsorption isotherms were fitted by a linear model in this range of concentrations. Sugars were adsorbed in both resins by the following order: fructose > glucose > sucrose. Sucrose was more adsorbed in the Na+ macroporous resin, glucose...
Tipo: Article Palavras-chave: Adsorption isotherm; Macroporous resin; Gel-type resin; Cations; Sugars.
Ano: 2010 URL: http://hdl.handle.net/10198/3818
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