Browsing by Author "Veloso, Ana C.A."
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- Alterações dos parâmetros físico-químicos e sensoriais de azeite virgem extra durante o uso doméstico simulado ao longo de um mêsPublication . Rodrigues, Nuno; Oliveira, Letícia; Mendanha, Lorena; Sebti, Mohamed; Dias, L.G.; Oueslati, Souheib; Veloso, Ana C.A.; Pereira, J.A.; Peres, António M.O azeite tem características sensoriais e nutricionais únicas, o que torna altamente apreciado pelos consumidores. Neste trabalho estudaram-se as alterações da qualidade do azeite que podem ocorrer ao longo de um mês de consumo doméstico simulado.
- Alterações dos parâmetros físico-químicos e sensoriais de azeite virgem extra durante o uso doméstico simulado ao longo de um mêsPublication . Rodrigues, Nuno; Oliveira, Letícia; Mendanha, Lorena; Sebti, Mohamed; Dias, L.G.; Oueslati, Souheib; Veloso, Ana C.A.; Pereira, J.A.; Peres, António M.O azeite tem características sensoriais e nutricionais únicas, o que o torna altamente apreciado pelos consumidores
- Amino acids profile for assessing Serra da Estrela cheese producersPublication . Santos, Andreia O.; Falcão, Soraia; Fontes, Luísa; Veloso, Ana C.A.; Lemos, Edite Teixeira de; Lima, M.J. Reis; Peres, António M.; Dias, L.G.This work has the purpose to evaluate if the Serra da Estrela cheeses colletcted from 6 producers have typical chemical characteristics, with controlled variability, considering that cheeses were produced during time periods, the raw milk comes from different animals, and that the cheese processing may slightly differ between cheesemaking producers.
- Amino acids profile for assessing Serra da Estrela cheese producersPublication . Santos, Andreia O.; Falcão, Soraia; Fontes, Luísa; Veloso, Ana C.A.; Lemos, Edite Teixeira de; Lima, M.J. Reis; Peres, António M.; Dias, L.G.This work has the purpose to evaluate if the Serra da Estrela cheeses colletcted from 6 producers have typical chemical characteristics, with controlled variability, considering that cheeses were produced during time periods, the raw milk comes from different animals, and that the cheese processing may slightly differ between cheesemaking producers.
- Amino acids profile in Serra da Estrela cheese: a compreensive studyPublication . Lima, M.J. Reis; Fontes, Luísa; Santos, Andreia O.; Falcão, Soraia; Veloso, Ana C.A.; Lemos, Edite Teixeira de; Vilas-Boas, Miguel; Peres, António M.Milk and dairy products are of major importance in the human diet, since they are an excellent source of well-ballanced nutrients which are consumed in large amounts and are easy to manufacture.
- Amino acids profile in Serra da Estrela cheese: a compreensive studyPublication . Lima, M.J. Reis; Fontes, Luísa; Santos, Andreia O.; Falcão, Soraia; Veloso, Ana C.A.; Lemos, Edite Teixeira de; Vilas-Boas, Miguel; Peres, António M.Milk and dairy products are of major importance in the human diet, since they are an excellent source of well-ballanced nutrients which are consumed in large amounts and are easy to manufacture.
- An electronic nose as a non-destructive analytical tool to identify the geographical origin of portuguese olive oils from two adjacent regionsPublication . Rodrigues, Nuno; Ferreiro, Nuno Manuel; Veloso, Ana C.A.; Pereira, J.A.; Peres, António M.The geographical traceability of extra virgin olive oils (EVOO) is of paramount importance for oil chain actors and consumers. Oils produced in two adjacent Portuguese regions, Côa (36 oils) and Douro (31 oils), were evaluated and fulfilled the European legal thresholds for EVOO categorization. Compared to the Douro region, oils from Côa had higher total phenol contents (505 versus 279 mg GAE/kg) and greater oxidative stabilities (17.5 versus 10.6 h). The majority of Côa oils were fruity-green, bitter, and pungent oils. Conversely, Douro oils exhibited a more intense fruity-ripe and sweet sensation. Accordingly, different volatiles were detected, belonging to eight chemical families, from which aldehydes were the most abundant. Additionally, all oils were evaluated using a lab-made electronic nose, with metal oxide semiconductor sensors. The electrical fingerprints, together with principal component analysis, enabled the unsupervised recognition of the oils’ geographical origin, and their successful supervised linear discrimination (sensitivity of 98.5% and specificity of 98.4%; internal validation). The E-nose also quantified the contents of the two main volatile chemical classes (alcohols and aldehydes) and of the total volatiles content, for the studied olive oils split by geographical origin, using multivariate linear regression models (0.981 < R2 < 0.998 and 0.40 < RMSE < 2.79 mg/kg oil; internal validation). The E-nose-MOS was shown to be a fast, green, non-invasive and cost-effective tool for authenticating the geographical origin of the studied olive oils and to estimate the contents of the most abundant chemical classes of volatiles.
- An electronic tongue as a tool for assessing the impact of carotenoids’ fortification on cv. Arbequina olive oilsPublication . Murillo-Cruz, Mª Carmen; Rodrigues, Nuno; Bermejo‐Román, Ruperto; Veloso, Ana C.A.; Pereira, J.A.; Peres, António M.The consumption of carotenoids has several health benefits. It is known that the fortification of olive oils with carotenoids, namely β-carotene or lutein, enhanced the oils’ physicochemical properties, being a possible strategy to increase carotenoids intake. This study showed that a lab-made potentiometric electronic tongue, comprising lipid sensor membranes, could discriminate non-fortified olive oils from those fortified with different levels β-carotene or lutein (repeated K-fold cross-validation sensitivities: 87 ± 8%), confirming the impact of the fortification on the oils’ phenolic contents and sensory sensations. Moreover, the device could, semi-quantitatively, discriminate oils fortified with different amounts (0, 0.05, 0.10, and 0.15 mg/mL) of each carotenoid (repeated K-fold cross-validation sensitivities: 94 ± 9% and 97 ± 7%, for β-carotene and lutein, respectively). This could be related to the capability of detecting increasing levels of the carotenoids and to the ability to assess the changes induced by the addition of carotenoids on the total phenols’ contents and on the intensities of the basic taste sensations. Indeed, satisfactory first- or second-order correlations could be established between the centroids of the first discriminant functions of the linear discriminant models and the carotenoid fortification levels, the total phenols contents, as well as with the sweetness, bitterness, and pungency intensities of the fortified oils (0.865 ≤ R2 ≤ 0.998). The successful qualitative and (semi-)quantitative performance of the electronic tongue may foresee its future application as a practical and cost-effective tool for assessing the impact of the fortification of olive oils with carotenoids at the carotenoids, phenols, and basic taste levels.
- An electronic tongue for gliadins semi-quantitative detection in foodstuffsPublication . Peres, António M.; Dias, L.G.; Veloso, Ana C.A.; Meirinho, Sofia G.; Morais, Jorge Sá; Machado, Adélio 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. Moreover, the device never identified an ethanolic extract containing gliadins as “Gluten-free”. Finally, the system also allowed distinguishing “Gluten-free” and “Gluten-containing” foodstuffs (15 foods, including breads, flours, baby milked flours, cookies and breakfast cereals) with an overall sensitivity and specificity greater than 83%, using the signals of only 4 selected polymeric membranes (selected using a stepwise procedure). Since only one “Gluten-containing” foodstuff was misclassified as “Gluten-free”, the device could be used as a preliminary tool for quality control of foods for celiac patients.
- Analysis of acids and sugars in fruit-based drinks by SEC-UV-RIPublication . Sequeira, Cédric Basílio; Dias, L.G.; Morais, Jorge Sá; Veloso, Ana C.A.; Machado, Adélio A.M.; Peres, António M.Beverage industry produces a large and diverse range of soft drinks, beverages containing flavourings and/or fruit juices (sodas and fruit juices), of which t he quality and safety must be monitored to protect and satisfy customers. From the raw ingredients to the final product, quality control is needed to ensure product safety, quality, labelling, regulatory compliance and consistency. The development of analytical techniques for simultaneous analysis of different compounds essential to control the product quality, as an alternative to several independent traditional reference methods, is of major importance. Therefore, the present work reports the application of size exclusion chromatography (SEC), which allows carrying out analysis free of organic solvents, using two detectors coupled in series - Ultraviolet (UV) and Refractive Index (RI) - for the simultaneous analysis of acidifiers (citric, tartaric, lactic, acetic, malic and ascorbic acids, by UV), and sweeteners (sucrose, glucose and fructose by RI), in commercial non-alcoholic beverages with different levels of added fruit juice. Ascorbic acid is used as a stabilizer in the soft drinks, improving the beverage shelf-life stability due to its antioxidant properties. The results showed that the simultaneous calibrations for acid compounds (UV) and for glucose (RI) were straight-forward. On the other hand, for sucrose and fructose simultaneous analysis, the calibrations (RI) were more complex since the predictive models established had to take into account malic and tartaric acids interferences, regardless the good resolution between the peaks of sucrose and fructose. Finally, the results for sample analysis showed that all the sugars evaluated were present in the juice drinks as well as the citric, tartaric, malic and ascorbic acids. In all samples, lactic and acetic acids were not detected.