Browsing by Author "Ramos, Fernando"
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- Active Packaging: application of natural antioxidantsPublication . Sanches-Silva, Ana; Costa, Denise; Albuquerque, T.G.; Castilho, Maria Conceição; Ramos, Fernando; Machado, Ana V.; Costa, H.S.Natural antioxidants applied in Active food Packaging: Food oxidation; Antioxidants; Food Packaging; Active Packaging; Legislation; Natural antioxidants.
- Advances in phenolic compounds analysis of aromatic plants and their potential applicationsPublication . Carvalho-Costa, Denise; Costa, H.S.; Albuquerque, T.G.; Ramos, Fernando; Castilho, Maria Conceição; Sanches-Silva, AnaBackground: Aromatic plants may contribute for human health promotion due to their antioxidant properties and also by replacing added salt in foods. Phenolic compounds are one of the major groups contributing for aromatic plants properties, including the prevention of cancer, cardiovascular and neurodegenerative diseases. Scope and approach: This review focuses on the main uses of aromatic plants generally recognized as safe (GRAS) and overviews the extraction, purification and analytical methods used to determine phenolics in these food matrices. The current state of the art is evaluated and future trends in the analysis of these compounds and food industry applications are discussed. Key findings and conclusions: In general, aromatic plants are complex matrices regarding their content on phenolic compounds. Their composition can be affected by the chemical structure of the studied analytes, the selected methods, the composition/nature of the aromatic plant and storage conditions. The most usual separation technique to determine these compounds is High Performance Liquid Chromatography (HPLC) coupled with ultraviolet (UV) or diode array detectors (DAD), although the use of mass spectrometry (MS) detectors is increasing. The future trends include the use of more sophisticated and automated techniques in order to reduce both analysis time and the amount of solvents used. Food industry widely uses aromatic plants, but other industries like food packaging, cosmetics, perfumery and pharmaceutical can also benefit from their properties.
- Antioxidant activity evaluation of Rose apple and Surinam cherry from Madeira IslandPublication . Ferreira, Joana O.; Costa, Denise; Castilho, Maria Conceição; Sanches-Silva, Ana; Albuquerque, T.G.; Ramos, Fernando; Costa, H.S.Rose apple or jambu (Syzygium jambos L.), Surinam cherry (Eugenia uniflora L.) are tropical fruits from Madeira Island. Rose apple is reddish and rose-scented while Surinam cherry is a small eight-ribbed fruit, of about 2-3 cm and ranges from orange to red colour. The goal of this study was to evaluate their antioxidant activity using two methods, β-carotene bleaching assay and 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•) scavenging assay. The extract concentration providing 50% inhibition of DPPH radical (EC50) was calculated from the graph of scavenging effect percentage against extract concentration in the solution. The β-carotene bleaching assay studied the ability of the extracts to avoid the oxidative bleaching of β-carotene in a β-carotene/linoleic acid emulsion. DPPH• reduction assay showed higher antioxidant activity of Surinam cherry (EC50 = 3.74 ± 0.09 mg/mL) than Rose apple (EC50 = 10.0 ± 0.21 mg/mL). β-carotene bleaching assay showed an antioxidant activity capacity (AAC) also higher for Surinam cherry (AAC=831.5) than for Rose apple (AAC=582.5). Surinam cherry showed better antioxidant capacity in both trials. Madeira Island has many tropical fruits with antioxidant activity, which could improve health status, by preventing diseases caused by oxidative stress, since these bioactive compounds can help to counteract the oxidizing agents. The results of this study indicate that both Rose apple and Surinam cherry have potential as antioxidants sources. In the future more research is needed in order to identify the compounds responsible for the antioxidant properties.
- Antioxidant and antimicrobial properties of PLA based active packaging with pomegranate peels and extractPublication . Andrade, Mariana; Rodrigues, Pedro; Barros, Carolina; Cruz, Vasco; Machado, Ana; Barbosa, Cássia; Coelho, Anabela; Furtado, Rosália; Correia, Cristina; Saraiva, Margarida; Vilarinho, Fernanda; Ramos, Fernando; Sanches Silva, AnaActive food packaging’ primary goal is to extend foodstuffs’ shelf life, through a dynamic and continuous interaction between the package and the packaged food. In an emission active packaging, the objective is the gradual release of antioxidant and/or antimicrobial compounds into the food surface, to delay the natural foods’ degradation. The active compounds can be extracted from several sources, such as aromatic plants, seaweeds, fruits by-products, among others. Since 50% of pomegranate is composed by peels, and since it is mainly consumed in juice and jam form, pomegranate peels may represent a considerable asset for the extraction of such compounds. The principal objective of this work was to evaluate the antioxidant and antimicrobial properties of polylactic-based active packaging incorporated with 3% (w/w) of pomegranate peels (PLA/3PP) and 3% (w/w) of pomegranate peels extract (PLA/3PPE). For the in vitro antioxidant activity evaluation, 9.08 cm2 of films were immersed in the food simulator, ethanol 95% (v/v), at 40 °C for 10 days. Then, the DPPH radical scavenging assay was performed, as well as the total content of phenolic compounds, total content in flavonoids, content in punicalagin (A+B) and ellagic acid were determined. Also, to fully determine the total content in punicalagin (A+B) and ellagic acid, the films were kept in methanol at 25 and 40 °C for 24 h. The antimicrobial activity of the films was evaluated with Listeria monocytogenes, Staphylococcus aureus, Enterococcus faecalis, and Escherichia coli, in accordance with ISO 22196:2011. Results showed that PLA/3PPE presented a higher antioxidant potential and higher content in phenolic compounds and flavonoids. Only ellagic acid was detected in the active PLA-based films. Regarding the antimicrobial activity, both films presented antimicrobial activity against S. aureus.
- Antioxidantes naturales aplicados a envases activos alimentarios: evolución recientePublication . Sanches-Silva, Ana; Costa, Denise; Albuquerque, T.G.; Castilho, Maria Conceição; Ramos, Fernando; Machado, Ana V.; Costa, H.S.Recent Advances in Antioxidant Active Food Packaging: Food oxidation; Antioxidants; Food Packaging; Active Packaging; Legislation; Natural antioxidants.
- Atividade antimicrobiana: extrato de chá verde versus ácido poliláctico com o extrato incorporadoPublication . Martins, Cristiana; Maia, Carla; Furtado, Rosália; Correia, C.B.; Vilarinho, Fernanda; Sanches Silva, A.; Ramos, Fernando; Castilho, M.C.As folhas de cha verde (Camellia sinensis (L.) Kuntze) contem, na sua constituicao quimica, uma percentagem elevada de polifenois, que sao considerados otimos agentes antioxidantes e antimicrobianos. Este trabalho teve como objetivo avaliar a atividade antimicrobiana do extrato de cha verde e do filme de acido polilactico (PLA), destinado a aplicacoes alimentares, com extrato de cha verde incorporado em diferentes concentracoes, 1% e 2%. A atividade antimicrobiana foi avaliada utilizando estirpes padrao das bacterias Gram-positivas Staphylococcus aureus, Listeria monocytogenes, Enterococcus faecalis e Bacillus cereus e das bactérias Gram-negativas Escherichia coli, Pseudomonas aeruginosa e Salmonella Thyphimurium. Placas de Agar Mueller Hinton foram inoculadas com os microrganismos em estudo. Para o extrato de cha verde, a atividade antimicrobiana foi testada pelo metodo de difusao em pocos preenchidos com o extrato. Para testar a atividade antimicrobiana dos filmes foram colocados, em contacto com a superfície de agar, os filmes PLA com extrato de cha verde (1% e 2%) (filmes ativos) e sem extrato (filme controlo). Procedeu-se de seguida a incubacao das placas em condicoes de tempo e temperatura de acordo com cada microrganismo. A atividade antimicrobiana foi estimada a partir dos halos de inibicao total de crescimento microbiano Os resultados revelaram que o extrato de cha verde apresentou atividade antibacteriana sobre as bactérias Gram positivas estudadas (Staphylococcus aureus, Listeria monocytogenes, Enterococcus faecalis e Bacillus cereus). No entanto, quando e incorporado nos filmes ativos, nas concentracoes 1% e 2%, nao apresenta capacidade antimicrobiana sobre nenhum dos microrganismos testados. A quantidade de extrato de cha verde incorporado no acido polilactico e/ou metodo utilizado na incorporacao podem justificar os resultados obtidos.
- Avaliação da capacidade antioxidante de extratos de Fucus vesiculosus para aplicação a embalagens alimentares ativasPublication . Andrade, Mariana; Reboleira, J.; Bernardino, S.; Ganhão, R.; Mendes, S.; Vilarinho, Fernanda; Sanches Silva, A.; Ramos, FernandoA indústria alimentar usa antioxidantes sintéticos para prevenir a degradação natural dos alimentos com alto teor lipídico causada, em grande parte, por fenómenos de oxidação. Estes antioxidantes, incluindo o BHT e o BHA, têm sido nas últimas décadas associados a efeitos negativos sobre a saúde humana, como a promoção da carcinogénese e reações alérgicas [1,2]. Atualmente, a maioria dos alimentos é adquirida numa embalagem que, na sua grande maioria, são feitas de plástico, obtido através de fontes não renováveis. O grave problema ambiental que se coloca com estas embalagens, aliado à procura e exigência dos consumidores por produtos naturais e com mínimo impacto ambiental, tem impulsionado a indústria e a comunidade científica a procurar alternativas, quer para as embalagens, quer para os antioxidantes sintéticos. Nesta linha de pensamento, foram criadas as embalagens alimentares ativas antioxidantes que interagem intencionalmente com o alimento embalado, libertando para o mesmo compostos bioativos capazes de retardar ou inibir a oxidação dos mesmos, aumentando assim o seu tempo de vida útil. A Fucus vesiculosus, também conhecida como fava-do-mar, é uma macroalga castanha (Phaeophyceae) presente em zonas frias e temperadas do Oceano Atlântico Norte, com uma poderosa capacidade antioxidante [3,4]. Na sua constituição, esta macroalga tem vários compostos bioativos, como os polissacarídeos sulfatados, que possuem poderosas atividades biológicas como atividades anti-tumorais, antioxidantes e antimicrobianas. O objetivo deste trabalho foi avaliar a capacidade antioxidante de cinco extratos hidro-etanólicos de F. Vesiculosus para avaliar o seu potencial de aplicação a embalagens alimentares ativas. Os extratos foram obtidos da alga seca e da alga liofilizada. Os ensaios de avaliação da capacidade antioxidante utilizados foram o Sistema de Inibição do Radical DPPH (2,2-diphenyl-1-picrylhydrazyl) e o Ensaio do Branqueamento do β-caroteno. Os extratos obtidos a partir da alga liofilizada obtiveram uma melhor capacidade antioxidante do que os extratos obtidos a partir da alga seca. Esta diferença pode ser explicada pela diferença de temperatura, uma vez que no caso da alga liofilizada, esta é seca através de um processo com baixas temperaturas, o que acaba por conservar os compostos bioativos da alga. O mesmo não acontece com a alga seca através de um processo normal de secagem.
- Citrus By-Products: Valuable Source of Bioactive Compounds for Food ApplicationsPublication . Andrade, Mariana A.; Barbosa, Cássia; Shah, Muhammad Ajmal; Ahmad, Nazir; Vilarinho, Fernanda; Khwaldia, Khaoula; Sanches Silva, Ana; Ramos, FernandoCitrus production produces about 15 million tons of by-products/waste worldwide every year. Due to their high content of bioactive compounds, several extraction techniques can be applied to obtain extracts rich in valuable compounds and further application into food applications. Distillation and solvent extraction continues to be the most used and applied extraction techniques, followed by newer techniques such as microwave-assisted extraction and pulsed electric field extraction. Although the composition of these extracts and essential oils directly depends on the edaphoclimatic conditions to which the fruit/plant was exposed, the main active compounds are D-limonene, carotenoids, and carbohydrates. Pectin, one of the most abundant carbohydrates present in Citrus peels, can be used as a biodegradable polymer to develop new food packaging, and the extracted bioactive compounds can be easily added directly or indirectly to foods to increase their shelf-life. One of the applications is their incorporation in active food packaging for microbiological and/or oxidation inhibition, prolonging foods’ shelf-life and, consequently, contributing to reducing food spoilage. This review highlights some of the most used and effective extraction techniques and the application of the obtained essential oils and extracts directly or indirectly (through active packaging) to foods.
- Determinação do ergosterol no cogumelo ostra (Pleurotus ostreatus) cultivado em borras de café e palha de trigoPublication . Ricardo, Sofia; Sanches-Silva, Ana; Ramos, Fernando; Castilho, Maria ConceiçãoUm dos cogumelos comestíveis que tem suscitado maior interesse nos últimos anos é o Pleurotus ostreatus, conhecido como cogumelo ostra, devido à facilidade de cultivo e ao seu grande potencial económico e qualidade nutricional. Existe, assim, a necessidade de estudar a sua composição em nutrientes e compostos bioativos para valorizar o seu cultivo. Este estudo teve por objetivo determinar o teor de ergosterol, por Cromatografia Líquida de Alta Eficiência acoplada a detetor de Ultravioleta-Visível, do cogumelo Pleurotus ostreatus cultivado em diferentes substratos, nomeadamente, borras de café e palha de trigo. Verificou-se que as amostras de cogumelo P. ostreatus cultivadas em borras de café apresentaram uma concentração de ergosterol superior (4,06 ± 0,32 mg/g de matéria seca) relativamente às amostras da mesma espécie de cogumelo cultivadas em palha de trigo (3,34 ± 0,19 mg/g de matéria seca). O uso das borras de café no substrato de crescimento de cogumelos ostra permitiu um aumento da concentração de ergosterol. No futuro seria de todo o interesse avaliar a influência do uso deste subproduto no substrato de crescimento de outras espécies comestíveis de cogumelos e no teor de outros compostos bioativos.
- Effect of pomegranate peels and extract in barrier, optical and mechanical properties of polylactic acid-based active packagingPublication . Andrade, Mariana; Vilarinho, Fernanda; Rodrigues, Pedro; Barros, Carolina; Cruz, Vasco; Machado, Ana Vera; Barbosa, Cássia; Ramos, Fernando; Sanches Silva, AnaBeing more than 50 % of pomegranate (Punica granatum L.) constituted by non-edible parts, namely peels (50%) and seeds (10%), pomegranate is an excellent source of by-products. Its peels and seeds present excellent antioxidant and antimicrobial activities and a high content of phenolic compounds, namely ellagitannins. This work aimed to evaluate the mechanical and optical properties of two polylactic acid (PLA)-based active packaging with 3 wt.% pomegranate peels (3PP) or 3 wt.% pomegranate peel extract (3PPE). All the samples were produced on a laboratory scale with techniques and processing conditions used in industry. The production of packaging with flexible films is mainly carried out by tubular film extrusion. With this processing method it is possible to produce samples with molecular orientation and reduced thickness equal to that of the packages currently on the market. The structural and morphological characterization of the films were evaluated by FTIR and SEM, and the color by UV-vis. Water vapor transmission and mechanical properties were also measured. The color was measured by Shimadzu UV2401PC reflectance spectrophotometer. Water vapor transmission, oxygen permeability and mechanical properties were also measured. The FTIR and SEM results indicate the incorporation of the pomegranate peels and peels extract in the PLA matrix, where PLA/3PPE showed better particle homogenization than the PLA/3PP. Regarding the color variations, the PLA/3PPE presented higher variations in terms of L*, a*, and b*. The incorporation of pomegranate derivates has a negative effect on the tensile strength and Young modulus, but a significant increase of the elongation at break for PLA/3PPE. The PLA film's water vapor barrier properties do not suffer any alteration with the incorporation of pomegranate extract.