Browsing by Author "Rodrigues, Nuno"
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- Adherence to Mediterranean Diet and olive oil consumption in national and international academics: a pilot studyPublication . Meireles, Manuela; Almeida-de-Souza, Juliana; Boto, Joana Margarida; Rodrigues, Nuno; Ferro-Lebres, VeraMediterranean Diet has been considered one of the healthiest and sustainable dietary patterns existent, being also recognized as an Intangible Cultural Heritage of Humanity by United Nations Educational, Scientific and Cultural Organization (UNESCO). One of the central aspects of Mediterranean Diet is olive oil consumption. Bragança is located at a region of a long tradition of olive oil production and consumption, however is not clear whether new generations are keeping this traditional heritage and if people coming from other countries adopt this cultural tradition of olive oil consumption and adherence to a Mediterranean Diet.
- Advantages and disadvantages of flavouring olive oilsPublication . Lamas, Sandra; Rodrigues, Nuno; Peres, António M.; Pereira, J.A.Flavoured and fortified olive oils have been a growing trend, meeting consumer preferences and offering differentiated and innovative products. However, these preparations can positively or negatively affect the physicochemical and sensory characteristics. The most noticeable changes occur in sensory terms, which can lead to the appearance of desired sensations, depending on the flavouring agent used. On the other hand, it can mask the presence of any sensory defect present in the olive oil. For the physicochemical characteristics and stability, flavouring can influence the levels of antioxidants and increase the olive oils' shelf-life, increasing the incorporation of antioxidant compounds, promoting oxidative stability and reducing oxidation. However, some studies report that incorporating flavouring agents has pro-oxidant effects. Generally, three techniques are used for flavouring olive oils: i) through permanent or temporary contact with the flavouring agent, ii) by co-extraction, and iii) the the addition of essential oils1. From them, direct contactbetween the olive oil and the flavouring agent is the most usual and traditional technique. Currently, natural extracts rich in a certain compound, such as lycopene or lutein, in the olive oils are used to fortify olive oils2. These extracts are incorporated to enrich it in a certain compound or set of compounds, with nutritional and healthy properties but without sensory objectives. Nevertheless, fortification can cause turbidity in the olive oil and/or can promote the appearance of unpleasant sensory sensations. For the present work, a vast bibliographic review3 was done devoted to the flavouring of olive oils, pointing out the interest in this ancient Mediterranean practice, as well as the diversity of techniques, agents and effects of the flavouring process. Based on the available data, it can be stated that the use of flavouring by direct contact is the most studied technique, which could be attributed to the easily of implementation of this technique, not requiring any change in the usual oil extraction process. Furthermore, considering that flavouring is performed directly on the extracted oils, the desirable sensory properties of the flavouring agent can migrate to the olive oil. Even so, a considerable number of studies still report the production of flavoured olive oils by co-extraction or by adding essential oils. However, a lower but significant number of studies have focused on the enrichment of olive oil with specific bioactive compounds, mainly antioxidants, to enhance the nutritional and healthy properties of olive oils. Regarding the used flavouring agents and based on the compiled literature (Figure 1), different classes can be grouped, namely aromatic plants, which represent more than 42% of the references compiled in this work, followed by spices, with around 24% of the references, fruits, with 14%, and the other agents representing around 19%. Within the aromatic plants, oregano and rosemary were the most common agents (14 references), followed by thyme (12 references) and basil(9 references). The lemon dominates with eight references in fruit, followed by tomato (with 7) and orange (3 references). Regarding spices, three flavouring agents should be highlighted, namely garlic (11 references), pepper (7 references) and chilli (4 references). In the other flavouring agents, the olive leaves had been frequently used (11 references), which is justified as a by-product of olive growing. The huge use of aromatic plants could be related to different factors, such as the wide range of flavours and aromas, the great availability, low price and easiness of use. It is also possible to infer that different, sometimes contradictory, effects were obtained by different studies when using the same flavouring agent or the same flavouring technique. These differences may be due to or attributed to different factors, which must be considered when comparing similar studies, such as the conditions under which the flavouring is carried out (time, temperature), the amount of flavouring agent used and itsstate (dry, fresh, powdered), the chemical composition of the flavouring and its storage conditions before use. Hence, the world of flavoured olive oils still needs to be further studied, being clear the need to go through a path that would allow the standardization of this Mediterranean tradition, aiming to limit and/or overcome the intrinsic variabilities of the flavouring/fortification commercial strategies.
- Advantages and disadvantages of flavouring olive oilsPublication . Lamas, Sandra; Rodrigues, Nuno; Peres, António M.; Pereira, J.A.Flavoured and fortified olive oils have been a growing trend, meeting consumer preferences and offering differentiated and innovative products. However, these preparations can positively or negatively affect the physicochemical and sensory characteristics. The most noticeable changes occur in sensory terms, which can lead to the appearance of desired sensations, depending on the flavouring agent used. On the other hand, it can mask the presence of any sensory defect present in the olive oil
- 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
- Alterações químicas do azeite das Cvs Negrinha de Freixo e Santulhana com a maturação do frutoPublication . Rodrigues, Nuno; Laira, Matheus; Cruz, Rebeca; Pinho, Teresa; Casal, Susana; Pereira, J.A.Diferentes trabalhos têm demonstrado que o grau de maturação das azeitonas influi na composição do azeite extraído, com alterações ao nível da sua composição química e sensorial. No entanto, não existe qualquer informação para as cultivares Negrinha de Freixo e Santulhana produzidas em Trás-os-Montes, sendo a primeira maioritária no concelho de Freixo de Espada à Cinta e a segunda largamente difundida nos concelhos de Bragança e Macedo de Cavaleiros. Assim, no presente trabalho foram colhidos frutos das duas cultivares em quatro índices de maturação distintos (l, 2, 3 e 4)nos quais se extraiu o azeite numa linha de extraçâo laboratorial. Os azeites obtidos foram caraterizados no que respeita aos parâmetros de qualidade (acidez, índice de peróxidos, coeficientes de extinção específica no ultravioleta e avaliação sensorial), resistência à oxidação pelo método de Rancimat, perfil em ácidos gordos e teor em tocoferóis. Os resultados obtidos indicam que todos os azeites poderiam ser classificados na categoria de Azeite Virgem Extra, uma vez que não apresentaram qualquer defeito sensorial, a média do frutado foi superior a zero e os restantes parâmetros se encontravam dentro dos limites estabelecidos pelo Regulamento (CEE) no 2568/91 e alterações posteriores para essa categoria. Ao nível da composição em ácidos gordos, as cultivares avaliadas são diferentes entre si, mas dentro da cultivar não se registou qualquer influência do índice de maturação na sua composição. No que respeita ao teor em tocoferóis, o seu perfil é semelhante tendo sido identificados o a-tocoferol, p-tocoferol e v-tocofèrol, com teor de tocoferóis totais a variar entrel65,08 e 178,96 mg/Kg de azeite, para a Cv. Negrinha de Freixo, e entre 279,64 e 219,15 mg/Kg de azeite para a cv Santulhana. Na Cv. Negrinha de Freixo o índice de maturação dos frutos apenas exerceu alguma influência ao nível do teor em y-tocoferol, com ligeiros aumentos ao longo da maturação. Por sua vez na Cv. Santulhana, registou-se uma diminuição no teor destes compostos, na ordem dos 20%. com a maturação do fruto. Os resultados vêm comprovar que nestas cultivares a maturação dos frutos influi na composição do azeite obtido em modos semelhantes aos registados em outras cultivares produzidas na mesma região mas cada cultivar apresenta características específicas.
- An Artificial Intelligence-Based Method to Identify the Stage of Maturation in Olive Oil MillsPublication . Mendes, João; Lima, José; Costa, Lino; Rodrigues, Nuno; Leitão, Paulo; Pereira, Ana I.Identifying the maturation stage is an added value for olive oil producers and consumers, whether this is done to predict the best harvest time, give us more information about the olive oil, or even adapt techniques and extraction parameters in the olive oil mill. In this way, the proposed work presents a new method to identify and count the number of olives that enter the mill as well as their stage of maturation. It is based on artificial intelligence (AI) and deep learning algorithms, using the two most recent versions of YOLO, YOLOv7 and YOLOv8. The obtained results demonstrate the possibility of using this type of application in a real environment, managing to obtain a mAP of approximately 79% with YOLOv8 in the five maturation stages, with a processing rate of approximately 16 FPS increasing this with YOLOv7 to 36.5 FPS reaching a 66% mAP.
- 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 as a tool for discriminating canned tuna with different coating oilsPublication . Lamas, Sandra; Peres, António M.; Pereira, J.A.; Rodrigues, NunoCanned fish is a food highly appreciated in Europe, with a great tradition in European and Mediterranean cuisines. In recent years there has been a growing demand for canned fish (e.g., sardines, tuna), either because of its usefulness and ease of use, but above all due to the health benefits related with this type of food. There has also been a growing trend in the market for providing differentiated products, traditionally called gourmet, with the emergence of new recipes, seasonings, and topping liquids. Canned foods are usually commercialized with different coating liquids, including natural preserves (water), with vegetable oils or olive oils with different commercial grades. This latter strategy is quite popular as a way of valuing and differentiating this type of canned food. However, the interaction between the fish and the coating liquid during storage, together with the technological processing of the canned food turns the authenticity assessment a hard analytical task, which is of major relevance considering the high price and the premium market envisaged for commercialization. Thus, this work aimed to evaluate the use of a potentiometric electronic tongue to discriminate canned tuna with different coating oils, namely, olive oil (extra virgin or virgin olive oil), refined olive oil and sunflower oil. Fifteen tuna samples were acquired, including five canned cans from different commercial brands for each studied oil. The samples were drained for 2 min, the tuna was removed from each can, extracted with a methanol-water solution (80:20, v/v) and then analysed with the electronic tongue (E-tongue). In total, for each sample, 40 potentiometric signal profiles were recorded by the 40 lipid sensor membranes comprised in the lab-made E-tongue (Figure 1)1. The results clearly showed that the acquired E-tongue profiles together with chemometrics (linear discriminant analysis coupled with the simulated annealing variable selection algorithm, LDA-SA), allowed correctly classifying 100% (Figure 2) of the original grouped data (training). The LDA-SA-E-tongue model was based on the potentiometric signals recorded by 7 of the 40 sensors, leading to a satisfactory predictive performance (internal validation), namely 93% and 86% for leave-one-out cross-validation and repeated K-fold cross-validation (4 folds and 10 random split repeats) procedures. In conclusion, the E-tongue could be foreseen as a practical and accurate tool for guaranteeing the label correctness of tuna canned cans according to the coating oil used, namely allowing a clear recognition of the type of vegetable oil used, i.e., sunflower or olive oil.