Browsing by Author "Lamas, Sandra"
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- 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
- 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.
- Aplicação de óleos essenciais na conservação de cerejas cv. SummitPublication . Lamas, Sandra; Ferreiro, Nuno Manuel; Silva, Kevin; Ramalhosa, Elsa; Pereira, J.A.; Rodrigues, NunoA cereja (Prunus avium L.) é um fruto com teores elevados em açúcares, compostos fenólicos, antocianina, etc. Em Portugal, a produção está maioritariamente concentrada nas regiões do Fundão, Resende e Alfandega da Fé. Contudo, o fruto é muito perecível, e necessita de ser conservado a baixas temperaturas. A utilização de óleos essenciais (OE), pela sua reconhecida ação antimicrobiana, tem sido proposta como agentes capazes de aumentar o período de pós-colheita de frutos. Nesse sentido, este trabalho teve como objetivo estudar o efeito da aplicação de 2 OE, de laranja (Citrus sinesis cv. Late) e de lavanda (Lavanda angustifolia Mill), em pós-colheita de cereja Cv. Summit. Para tal, foram colocadas 100g de cerejas em caixas de plástico individuais, nas quais na parte superior se colocou um papel de filtro de 1 cm2 humedecido com 10 μl de OE. As cerejas foram armazenadas sob refrigeração (5 ºC) e a cada 5 dias, durante 30 dias, foi avaliada a qualidade dos frutos (acidez, pH, brix, textura, cor, força de rutura do pedúnculo, número de frutos impróprios para consumo e perdas de massa). Para cada observação, foram avaliadas 3 amostras independentes. Os resultados obtidos demonstraram uma degradação dos parâmetros ao longo do ensaio, verificando, que o tratamento com OE de laranja reduziu, em T30 dias, o número de frutos impróprios para consumo (8,3 % ± 7,2), quando comparado com o controlo (36,6% ± 9,5) e o tratamento com OE de lavanda (37,7 % ± 7,4). Os restantes parâmetros avaliados não apresentaram diferenças significativas entre tratamentos.
- Application of the FTIR technique as a non‐invasive tool to discriminate Portuguese olive oils with protected designation of originPublication . Lamas, Sandra; Ruano, Daniela Filipa Magalhães; Dias, Francisco; Barreiro, M.F.; Pereira, J.A.; Peres, António M.; Rodrigues, NunoThree Portuguese olive oils with PDO (‘Azeite do Alentejo Interior’, ‘Azeites da Beira Interior’ and ‘Azeite de Trás-os-Montes’) were studied considering their physicochemical quality, antioxidant capacity, oxidative stability, total phenols content, gustatory sensory sensations and Fourier transform infrared (FTIR) spectra. All oils fulfilled the legal thresholds of EVOOs and the PDO's specifications. Olive oils from ‘Azeite da Beira Interior’ and ‘Azeite de Trás-os-Montes’ showed greater total phenols contents and antioxidant capacities, while ‘Azeites da Beira Interior′ presented higher oxidative stabilities. Linear discriminant models were developed using FTIR spectra (transmittance and the 1st and 2nd derivatives), allowing the correct identification of the oils’ PDO (100 % sensitivity and specificity, repeated K-fold-CV). This study also revealed that multiple linear regression models, based on FTIR transmittance data, could predict the sweet, bitter, and pungent intensities of the PDO oils (R2≥0.979±0.016; RMSE≤0.26±0.05, repeated K-fold-CV). This demonstrates the potential of using FTIR as a non-destructive technique for authenticating oils with PDO.
- Aromatização e fortificação de azeites virgens - Análise da situação no mercado portuguêsPublication . Lamas, Sandra; Pereira, J.A.; Rodrigues, NunoA aromatização e fortificação de azeites virgens é uma tendência em crescimento. Sendo que, os azeites aromatizados e fortificados podem apresentar algumas vantagens. No caso dos azeites aromatizados, podem contribuir para o enriquecimento das caraterísticas sensoriais, aumento do tempo de vida útil, incorporação de compostos com atividades biológicas, como por exemplo antioxidantes que contribuem para o aumento da resistência à oxidação. Como desvantagens da aromatização de azeites aponta-se o fato da adição de aromatizantes poder contribuir para mascarar defeitos sensoriais, e desta forma constituir uma fraude para o consumidor. Em termos sensoriais, o excesso de aromatizante pode tornar desagradável o sabor do azeite. Por sua vez a fortificação terá a vantagem de incorporar um determinado composto ou extrato com propriedades específicas, contribuindo desta forma para o enriquecimento biológico do azeite, mas também pode aumentar a turbidez e ter um aspeto menos agradável e sensorialmente menos apelativo para o consumidor. Assim, este trabalho teve como objetivo avaliar a situação acerca dos azeites aromatizados comercializados no mercado nacional. Desse modo, realizou-se um levantamento das empresas que comercializam azeites aromatizados, obtendo 64 empresas, distribuídas por todo o território nacional, que no seu conjunto comercializam 226 referências diferentes de azeites aromatizados. A grande maioria das empresas comercializa entre três e quatro referências de azeites aromatizados. Do total das referências analisadas 154 são azeites aromatizados com um único agente, dos quais 46 % correspondem à aromatização com plantas aromáticas, maioritariamente alecrim e orégãos. Em azeites com combinações de dois ou mais agentes aromatizantes as plantas aromáticas, maioritariamente loureiro e especiarias, sobretudo pimentas, representam 68 %. Nos azeites analisados, a capacidade líquida das embalagens que predomina foi de 250 mL, enquanto que a técnica de aromatização mais utilizada pelas empresas com 71,7 % é a aromatização por contato permanente entre o azeite e o agente aromatizante. O número de azeites fortificados foi muito baixo. Desse modo, o mercado nacional de azeites aromatizados disponibiliza uma vasta gama de opções, desde vários agentes aromatizantes, diferentes capacidades líquidas, vários métodos de aromatização e diferentes embalagens.
- Carob and pomegranate extracts enhance plant defence mechanisms against olive anthracnose through antioxidant activity and phenolic compounds productionPublication . Antón-Domínguez, Begoña I.; Sánchez-Pereira, Luiza; Lamas, Sandra; Rodrigues, Nuno; Baptista, Paula; Agustí-Brisach, CarlosOlive anthracnose (OA), caused by Colletotrichum species, is one of the most economically damaging disease in olive sector. This study was focused to identify sustainable control alternatives by evaluating the effect of pomegranate and carob extracts against OA and elucidating their mode of action. In vitro assays on mycelial growth, conidial production, and germination, and appressoria formation of C. godetiae and C. nymphaeae were performed. Neither extract significantly inhibited mycelial growth, while both reduced reproductive structures formation of the pathogens. Bioassays on detached and attached olive fruits in plants of cv. Arbequina, treated with extracts and/or inoculated with C. godetiae were conducted to evaluate the effect of the extracts on disease progression. Despite of the limited effect of the extracts on reducing disease progression in detached fruit, curative applications were more effective than preventive ones. Carob extract was more effective than pomegranate extract in reducing the disease incidence progression in attached fruit in planta. The resistance-inducing effect of plant extracts was evaluated by quantifying of H2O2 and phenolic compounds production in olive leaves at 0, 3, 7 and 24 h after inoculation with C. godetiae. Both extracts increased these parameters in the inoculated plants, with carob extract triggering an earlier activation and promoting a greater diversity of phenolic compounds accumulation. These findings reveals that these two extracts act as resistance inducers through different effective defence pathways, with carob extract standing out as a promising bioprotector against OA. These results open new possibilities for environmentally friendly management of OA using plant extracts.
- Different approaches to Olive Pomace valorisationPublication . Cordeiro, Ana; Lamas, Sandra; Rodrigues, Ana; Cadavez, Vasco; Silvério, Sara; Peres, António M.; Rodrigues, Lígia R.; Amorim, CláudiaOlive pomace (OP) is a substantial by-product, rich in lignocellulosic materials and water, obtained following the extraction of olive oil. It comprises the following components: olive skins, pulp, seeds, and stones. As global olive oil production continues to rise, the management and utilisation of OP have become increasingly important from both an economic and an environmental perspective [1]. In this study, the OP was chemically characterized and its potential as a source of value-added compounds was evaluated. For this purpose, several extraction studies were preformed, namely lipid extraction using petroleum ether, phenolic compound extraction with ethanol, and free sugar extraction with water using a Soxhlet system (Figure 1). These extractions allowed to recover 11.1 ± 0.3 % (w/w) of lipids, different types of phenolic compounds and oligosaccharides. Phenolic compounds are widely recognized for their health-promoting properties (e.g. antioxidant, anti-inflammatory, cancer prevention or antimicrobial activity) and have been the subject of extensive research. Oligosaccharides (OS) are short chains of monosaccharide units linked by glycosidic bonds. The ingestion of these compounds has been demonstrated to confer a multitude of salutary effects, predominantly due to their function as prebiotics and their capacity to regulate gut health and influence overall metabolic processes. Enzymatic hydrolysis was also performed using commercial xylanase from Trichoderma reesei, under optimal conditions (pH 4.5, 40°C, 150 rpm) to evaluate the potential of OP to produce xylo-based oligosaccharides [2]. The hydrolysis process was monitored through Thin Layer Chromatography (TLC), High-Performance Liquid Chromatography (HPLC) using different columns, and the Dinitrosalicylic acid (DNS) method (Figure 2). The results indicated the production of xylo-based oligosaccharides, validating the proposed bioprocess as a viable method for XOS production from OP. This approach not only provides value-added to OP but also aligns with sustainable waste management practices.
- Discriminação de azeites ‘Verdeal Transmontana’ de acordo com a idade das oliveiras recorrendo à espectroscopia no infravermelho por transformada de FourierPublication . Lamas, Sandra; Baptista, Paula; Santamaria-Echart, Arantzazu; Barreiro, Filomena; Peres, António M.; Pereira, José Alberto; Rodrigues, Nuno; Baptista, PaulaO efeito da idade das oliveiras na qualidade do azeite é ainda pouco conhecido. Nesse sentido, o presente trabalho teve como objetivo avaliar a influência da idade da oliveira na qualidade e composição dos azeites, usando a cv. Verdeal Transmontana como modelo. Para tal foram selecionadas 15 oliveiras jovens (< 20 anos), 15 com idade intermédia (entre 20 e 50 anos) e 15 centenárias (> 100 anos), de cujas azeitonas foram extraídos azeites. Nos azeites avaliaram-se os parâmetros de qualidade (acidez, índice de peróxidos, coeficiente de extinção específica no ultravioleta, avaliação sensorial), atividade antioxidante e estabelecidos os espetros no infravermelho por transformada de Fourier (FTIR). Todos os azeites obtidos podem ser classificados como azeite virgem extra. A idade da planta influenciou alguns parâmetros, sem que tenha uma tendência linear. Os azeites extraídos de oliveiras com idade intermédia, apresentaram valores superiores de atividade antioxidante e teor em fenóis totais. A aplicação da análise discriminante linear (LDA), conjuntamente com o algoritmo metaheurístico de seleção de variáveis (SA), aos espetros de FTIR, permitiram estabelecer um modelo FTIR-LDA-SA, com base nas transmitâncias (%) registadas para 10 números de onda selecionados (2860, 2856, 2783, 1329, 1094, 918, 739, 723, 683, e 615 cm-¹). O modelo apresentou sensibilidade e especificidade de 100%, permitindo identificar corretamente as idades de todas as oliveiras estudadas, com base nos espectros FTIR, de acordo com a validação cruzada k-fold. O sucesso alcançado na previsão permite concluir que a técnica FTIR pode ser usada como uma ferramenta não invasiva/não-destrutiva de identificação da idade das oliveiras com base nos espectros de transmitância dos azeites extraídos.
- Estudo das condições de termobatedura, à escala piloto, no rendimento de extração e caraterísticas do azeitePublication . Ruano, Daniela Filipa Magalhães; Souza, Thiago Pereira Pio de; Ferreiro, Nuno Manuel; Lamas, Sandra; Peres, António M.; Rodrigues, NunoA quantidade de pasta de azeitona (e, indiretamente, a área de transferência de calor), o tempo e a temperatura de batedura, influenciam o rendimento de extração, parâmetros de qualidade, actividade antioxidante (DPPH e fenóis totais), e perfil sensorial do azeite extraído.
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