Browsing by Author "Coimbra, Manuel A."
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- Application of Fourier transform infrared spectroscopy and orthogonal projections to latent structures/partial least squares regression for estimation of procyanidins average degree of polymerisationPublication . Passos, Cláudia P.; Cardoso, Susana M.; Barros, António S.; Silva, Carlos M.; Coimbra, Manuel A.Fourier transform infrared (FTIR) spectroscopy has being emphasised as a widespread technique in the quick assess of food components. In this work, procyanidins were extracted with methanol and acetone/water from the seeds of white and red grape varieties. A fractionation by graded methanol/chloroform precipitations allowed to obtain 26 samples that were characterised using thiolysis as pre-treatment followed by HPLC-UV and MS detection. The average degree of polymerisation (DPn) of the procyanidins in the samples ranged from 2 to 11 flavan-3-ol residues. FTIR spectroscopy within the wavenumbers region of 1800-700 cm(-1) allowed to build a partial least squares (PLS1) regression model with 8 latent variables (LVs) for the estimation of the DPn, giving a RMSECV of 11.7%, with a R(2) of 0.91 and a RMSEP of 2.58. The application of orthogonal projection to latent structures (O-PLS1) clarifies the interpretation of the regression model vectors. Moreover, the O-PLS procedure has removed 88% of non-correlated variations with the DPn, allowing to relate the increase of the absorbance peaks at 1203 and 1099 cm(-1) with the increase of the DPn due to the higher proportion of substitutions in the aromatic ring of the polymerised procyanidin molecules.
- Aspectos químicos y nutricionales del filete de Aloe veraPublication . Pinela, José; Añibarro-Ortega, Mikel; Barros, Lillian; Silva, Soraia P.; Coelho, Elisabete; Coimbra, Manuel A.; Ferreira, Isabel C.F.R.El Aloe vera (Aloe barbadensis Mill.) es una planta suculenta de la familia Asphodelaceae actualmente naturalizada en muchos países tropicales y subtropicales. En la medicina tradicional, se ha utilizado ampliamente durante siglos para tratar trastornos de la piel y otras enfermedades, así como por su efecto purgante [1]. Hoy en día, esta especie se usa como ingrediente para alimentos funcionales, cosméticos y medicamentos [2]. Las hojas son la parte más utilizada de la planta, en la que se pueden identificar dos fracciones principales, la corteza externa y el parénquima interno conocido como pulpa o filete. Aunque hay varios estudios sobre el Aloe vera [1,2], muchos de ellos tienen descripciones confusas, principalmente sobre el interior de la hoja, debido a los diferentes términos que se han usado indistintamente. En este sentido, en este trabajo se realizó una caracterización del valor nutricional y composición química del parénquima interno de la hoja (filete), que es la parte comestible de la planta. El filete de las hojas de Aloe vera fue separado de la cáscara y se determinó el contenido en humedad. Después, la muestra se liofilizó y se pulverizó y se determinó el contenido en proteína, grasa, cenizas, hidratos de carbono disponibles y fibra alimentaria. También se determinó la composición en ácidos orgánicos, ácidos grasos, tocoferoles, azúcares libres y polisacáridos de alto peso molecular utilizando diferentes técnicas cromatográficas. El perfil en compuestos fenólicos se caracterizó en un extracto hidroetanólico mediante HPLC-DAD-ESI/MSn. Se verificó que el filete corresponde aproximadamente al 58% de la masa de la hoja de Aloe vera y que su mayor constituyente es el agua (98%). En base seca, la fibra alimentaria resultó ser el macronutriente predominante (50.1%), constituida principalmente por manano (posiblemente acemanano), seguida por los hidratos de carbono disponibles (37.4%). Apenas 1% en grasa, 2.6% en proteína y 9% en cenizas, hacen que el filete sea un alimento de bajo poder calórico (4,5 kcal/100 g fw y 270 kcal/100 g dw). También se detectaron cantidades interesantes de α-tocoferol (5 mg/100 g dw) y ácido málico (5 g/100 g dw). Respecto al perfil fenólico, se detectaron de forma predominante cromonas (5.5 mg/g extracto) y antronas (5.3 mg/g extracto), incluyendo aloesina y aloínas A y B, respectivamente. El filete fresco de Aloe vera es un alimento bajo en calorías debido a su alto contenido en agua y bajo contenido en grasa. Además, se destaca por su contenido en tocoferoles, ácido málico y cromonas [3]. Todo esto hace que el filete de Aloe vera sea un ingrediente interesante para ser explorado tanto por la industria alimentaria como por la industria cosmética.
- Calcium-mediated gelation of an olive pomace pectic extractPublication . Cardoso, Susana M.; Coimbra, Manuel A.; Silva, J.A. Lopes daPectic raw material was extracted from the alcohol insoluble residue of olive pomace. After purification, the olive pectic extract (OPE) contained 48% of galacturonic acid (GalA) and 31% of arabinose, in a total sugar content of 72%, and a degree of methylesterification (DM) of 43%. Phase diagrams were established to define the physical state of the OPE/calcium, systems, at pH 3 and 7, as a function of GalA and calcium concentration. The theological properties of the OPE/calcium systems were investigated by small-amplitude oscillatory tests. Kinetics of gel ageing and the viscoelastic properties of the cured gels were evaluated as a function of GalA and calcium concentration at pH 3 and 7. Compared with the observed behaviour of a citrus pectin, taken as representative of a commercial low-methoxyl pectin, the OPE showed higher critical GalA and calcium concentrations for gelation to occur, a larger region corresponding to homogeneous gel, and gels characterised by lower viscoelastic moduli, at similar GalA and calcium concentrations.
- Composição glicosídica e actividade antioxidante de extractos de infusões de folhas de freixo (Fraxinus angustifolia)Publication . Martins, Vitor Manuel Ramalheira; Coimbra, Manuel A.Neste trabalho foram preparadas infusões de folhas de freixo secas. Cada infusão foi dividida em duas fracções, tendo uma sido utilizada para a obtenção do material polimérico por diálise (Dial) e a outra submetida a uma extracção em fase sólida C18, sendo a fase aquosa recolhida composta pelo material não retido (C18 H2O) e a fracção de metanol composta pelo material retido e eluído neste solvente (C18 MeOH). A análise da composição glicosídica mostrou que a fracção C18 H2O era rica em glucose e manose; a fracção C18 MeOH era rica em glucose e a fracção Dial era rica em ácidos urónicos, arabinose, galactose e glucose. A fracção C18 H2O era a mais pobre em compostos fenólicos e a que apresentou menor actividade antirradicalar. As fracções C18 MeOH e Dial apresentaram actividades antirradicalares semelhantes entre si, apesar de possuírem quantidades de compostos fenólicos totais distintas. A fracção Dial, constituída por material de peso molecular superior a 12-14 kDa, foi ainda sujeita a uma análise de ligações glicosídicas, através da análise por GC-MS dos respectivos acetatos de alditol parcialmente metilados. O resultado obtido permitiu inferir a presença de resíduos glicosídicos característicos de arabinogalactanas do tipo II, xiloglucanas e xilanas.
- Compositional features and bioactive properties of aloe vera leaf (Fillet, mucilage, and rind) and flowerPublication . Añibarro Ortega, Mikel; Pinela, José; Barros, Lillian; Ćirić, Ana; Silva, Soraia P.; Coelho, Elisabete; Mocan, Andrei; Calhelha, Ricardo C.; Soković, Marina; Coimbra, Manuel A.; Ferreira, Isabel C.F.R.This work aimed to characterize compositional and bioactive features of Aloe vera leaf (fillet, mucilage, and rind) and flower. The edible fillet was analysed for its nutritional value, and all samples were studied for phenolic composition and antioxidant, anti-inflammatory, antimicrobial, tyrosinase inhibition, and cytotoxic activities. Dietary fibre (mainly mannan) and available carbohydrates (mainly free glucose and fructose) were abundant macronutrients in fillet, which also contained high amounts of malic acid (5.75 g/100 g dw) and -tocopherol (4.8 mg/100 g dw). The leaf samples presented similar phenolic profiles, with predominance of chromones and anthrones, and the highest contents were found in mucilage (131 mg/g) and rind (105 mg/g) extracts, which also revealed interesting antioxidant properties. On the other hand, the flower extract was rich in apigenin glycoside derivatives (4.48 mg/g), effective against Pseudomonas aeruginosa (MIC = 0.025 mg/mL and MBC = 0.05 mg/mL) and capable of inhibiting the tyrosinase activity (IC50 = 4.85 mg/mL). The fillet, rind, and flower extracts also showed a powerful antifungal activity against Aspergillus flavus, A. niger, Penicillium funiculosum, and Candida albicans, higher than that of ketoconazole. Thus, the studied Aloe vera samples displayed high potential to be exploited by the food or cosmetic industries, among others.
- Enfoques integrados para el impulso socioeconómico de la producción y consumo sostenible de hongos de MontesinhoPublication . Saldanha, Ana Luísa; Gomes, Leonardo Corrêa; Pinela, José; Coimbra, Manuel A.; Barros, Lillian; Dias, Maria Inês; Pereira, CarlaEl Parque Natural de Montesinho representa un área de montaña con un patrimonio micológico único. Entre las aproximadamente doscientas setas comestibles que se encuentran en este espacio protegido, la mayoría se consumen desde la antigüedad por su exquisito sabor y valor nutritivo [1]. Sin embargo, la disponibilidad de estos productos de montaña está limitada por su estacionalidad y condiciones climáticas, cuestión que se intensifica con el cambio climático. Por otro lado, las prácticas insostenibles de recolección de hongos y el comercio ilegal de especies de alto valor también han sido prácticas comunes con impactos negativos en el ecosistema y la economía regional y nacional. Todas estas cuestiones, junto con la incapacidad de los recolectores locales para garantizar la autenticidad/inocuidad de las setas recolectadas, han llevado a muchos restaurantes a evitar su inclusión en sus menús, salvaguardando su negocio y la salud de los consumidores. Así, se propone la producción de apreciados hongos comestibles en ambiente controlado ex-situ. Se está realizando una extensa caracterización nutricional, química y biológica para asegurar la alta calidad de las especies producidas y la preservación de sus características originales. El desarrollo de un sello de calidad y seguridad, “Safe2Taste”, que garantiza la trazabilidad de toda la cadena de producción, tiene como objetivo aumentar la confianza/fidelidad de los consumidores en los productos
- Estrutura e atividade imunoestimuladora dos polissacarídeos presentes em extratos aquosos de inflorescências secas de P. tridentatumPublication . Martins, Vitor Manuel Ramalheira; Cruz, Maria T.; Ferreira, Isabel; Coimbra, Manuel A.As inflorescências secas da carqueja (P. tridentatum L.) são utilizadas na preparação de extratos aquosos que, de acordo com a tradição popular, possuem propriedades terapêuticas. Durante a preparação dos extratos ocorre a extração de compostos bioativos, tais como polissacarídeos. O presente trabalho pretende determinar o tipo de polissacarídeos presente nos extraías e avaliar o seu possível contributo para as respetivas propriedades terapêuticas. Procedeu- se à extração, caracterização estrutural e avaliação da atívidade imunoestimuladora dos polissacarídeos presentes nos extratos. Foi detetada uma mistura de polissacarídeos, nomeadamente polissacarídeos pécticos, arabinogalactanas do Tipo-I e II, galactomananas e xiloglucanas, que apresenta atividade imunoestimuladora em macrófagos e que poderá contribuir para as propriedades terapêuticas atribuídas pela medicina popular a estes extratos.
- Headspace solid phase microextraction (spme) analysis of flavor compounds in wines. Effect of the matrix volatile composition in the relative response factors in a wine modelPublication . Rocha, Sílvia; Martins, Vitor Manuel Ramalheira; Barros, António S.; Delgadillo, Ivonne; Coimbra, Manuel A.The application of headspace solid phase microextraction (SPME) for flavor analysis has been studied. Headspace SPME sampling was tested for nine common wine flavor compounds in 10% (v/v) aqueous ethanol: linalool, nerol, geraniol, 3-methyl-1-butanol, hexanol, 2-phenylethanol, ethyl hexanoate, ethyl octanoate, and ethyl decanoate. The chemical groups (monoterpenoids, aliphatic and aromatic alcohols, and esters) showed specific behavior in SPME analysis. SPME sampling parameters were optimized for these components. Relative response factors (RRFs), which establish the relationship between the concentration of the compound in the matrix liquid solution and the GC peak area, were estimated for all compounds. Log10(RRF) varied from 0 (3-methyl-1-butanol) to 3 (ethyl decanoate), according to their molecular weight. Quantification by SPME was shown to be highly dependent on the matrix composition; the compounds with higher RRF were the less affected. As a consequence, the data obtained with this methodology should be used taking into consideration these limitations, as shown in the analysis of four monovarietal Bairrada white wines (Arinto, Bical, Cerceal, and Maria Gomes).
- Immunostimulatory polysaccharides from the hot water extracts of prickled broom (P. tridentatum (L.) Willk) dried inflorescencesPublication . Martins, Vitor Manuel Ramalheira; Simões, Joana; Ferreira, Isabel; Cruz, Maria T.; Domingues, Maria R.M.; Coimbra, Manuel A.The decoctions of prickled broom (Pterospartum trídentatum (L.) Willk.) dried inflorescences have claimed beneficial properties for various health disorders [1, 2]. These can be assigned to several constituents, among them, the polysacharides. In order to unveil the contribution of the polysacharides and their structural features to the modulation of the innate immune activity, the hot water extracts from P. tridentatum dried inflorescences were prepared and fractionated by ethanol precipitation and anion exchange chromatography. A fraction that mainly contained pectic polysaccharides and acetylated galactomannans was isolated. This fraction evidenced in vitro immunostimulatory activity without compromising cellular viability, as evidenced by the increase registered in the nitric oxide (NO) production by macrophages. This activity decreased 60-75% after saponification, confirming that acetylation is an important structural feature for this biological property. In addition, the treatment of pectic polysaccharides with endo-polygalacturonase showed that type-1 and type-11 arabinogalactans, as well as low molecular weight galacturonans and xyloglucans, may also contribute to macrophage NO production. Thus, the polysaccharides present in the dried inflorescences of P. trídentatum may contribute to the health beneficial properties frequently attributed to the decoctions of this plant.
- In vitro macrophage nitric oxide production by Pterospartum tridentatum (L.) Willk. inflorescence polysaccharidesPublication . Martins, Vitor Manuel Ramalheira; Simões, Joana A.; Ferreira, Isabel C.F.R.; Cruz, Maria T.; Domingues, Maria R.M.; Coimbra, Manuel A.Pterospartum tridentatum (L.) Willk. decoctions of dried inflorescences are used in Portugal due to their claimed beneficial properties for various health disorders. To disclose the potential contribution of its polysaccharides to health benefits, in this work, hot water extracts from P. tridentatum inflorescences were prepared and fractionated by ethanol precipitation and anion exchange chromatography. The fraction rich in acetylated galactomannans evidenced an increase in nitric oxide (NO) production by macrophages. This activity decreased 60–75% after saponification, confirming that acetylation is an important structural feature for this biological property. In addition, the treatment of pectic polysaccharides with endo-polygalacturonase showed that type-I and type-II arabinogalactans, as well as low molecular weight galacturonans and xyloglucans, may also contribute to macrophage NO production. Thus, the polysaccharides present in P. tridentatum dried inflorescences may contribute to the health beneficial properties frequently attributed to the decoctions of this plant.