Browsing by Author "Soares, Maria Elisa"
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- Antioxidant activity and phenolic contents of Olea europaea L. leaves sprayed with different cooper formulationsPublication . Ferreira, Isabel C.F.R.; Barros, Lillian; Soares, Maria Elisa; Bastos, Maria de Lourdes; Pereira, J.A.The presence of cooper can catalyse oxidation of fatty acid chains, exerting a deleterious influence over shelf life. Transition metals, which possess two or more valence states with a sui tab le redox potential, act as pro-oxidants even at concentrations lower than 0.1 ppm, and could affect the speed of autoxidation and the direction of hydroperoxide breakdown to volatile le compounds. Being copper a transition metal that even, in small concentration, is a very potent oxidation catalyst, can enter a redox reaction, giving rise to consequent lipid peroxidation phenomenon due to the free radicals producing.
- Antioxidant activity and phenolic contents of Olea europaea L. leaves sprayed with different copper formulationsPublication . Ferreira, Isabel C.F.R.; Barros, Lillian; Soares, Maria Elisa; Bastos, Maria de Lourdes; Pereira, J.A.Olive trees (Olea europaea L. Cv. Cobranc¸osa) from the northeast of Portugal were sprayed with three different copper formulations [bordeaux mixture (copper sulphate + calcium hydroxide - 20% Cu), copper hydroxide (40% Cu) and copper oxychloride (50% Cu)] to control olive fungal diseases. The residues of copper in olive leaves, harvested at different times, were evaluated by atomic absorption spectrometry. At all the collection times, treated olive leaves had significantly higher copper contents, compared to the control. The different copper amounts in pesticide formulations lowered the leaves contents in total phenols and hence their antioxidant properties. Olive leaves sprayed with copper oxychloride possessed the highest copper levels and the lowest content in phenols, which influenced its antioxidant activity (higher EC50 values for reducing power, scavenging effect on DPPH radicals and inhibition of erythrocyte hemolysis). Leaves without copper residues proved to be a good natural source of antioxidants, giving values comparable to the reference compounds.
- Copper and lead residues in olives after olive tree treatments with three different copper formulations.Publication . Soares, Maria Elisa; Pereira, J.A.; Bastos, Maria de Lourdes
- Copper residues in olives after olive tree treatments with three different copper formulations.Publication . Soares, Maria Elisa; Pereira, J.A.; Bastos, Maria de Lourdes
- Extracção de nutrientes minerais do solo, de povoamentos de Castanea sativa Mill., pela colheita de cogumelos silvestres comestíveisPublication . Baptista, Paula; Meirinhos, Julieta; Martins, Anabela; Soares, Maria ElisaNo nordeste de Portugal, na última década tem-se assistido a uma intensificação da colheita e comercialização de cogumelos silvestres comestíveis. Apesar da grande diversidade de cogumelos existentes, os colectores, apenas procedem à colheita de algumas espécies, nomeadamente Hydnum rufescens, Boletus edulis, Cantharellus cibarius, Tricholoma acerbum, Xerocomus chrysenteron e em menor quantidade Clitopilus prunulus. Todos estes cogumelos são micorrizicos de Castanheiro. Com o presente trabalho pretendeu-se conhecer os teores de macronutrientes (Azoto – amoniacal e nítrico, fósforo e potássio total) e de alguns micronutrientes (cálcio e magnésio) mobilizados por estes fungos e por conseguinte retirados à cultura de Castanea sativa Mill.. Para tal, estabeleceram-se 3 talhões fixos de 100m2 num povoamento de Castanheiro na área do PNM onde, no período Outono-Inverno de 2002, se procedeu, semanalmente, à colheita dos cogumelos em estudo. A determinação de N e P foi efectuado por espectrofotometria UV/Vis e a de K, Ca e Mg por espectrofotometria de absorção atómica. Os resultados foram reportados à área expressa em ha tendo em conta a produção total de cogumelos em peso seco. De entre as espécies analisadas X. chrysenteron promoveu a maior remoção de NH4+ (125,58 g/ha), P (27,81 g/ha) e Mg (4,4 g/ha) do sistema, enquanto que o cogumelo B. edulis removeu maiores quantidades de K e Ca (172,92 mg/ha e 973,00 g/ha, respectivamente). C. cibarius e H. rufescens foram as espécies que menor quantidade de nutrientes removeram do sistema. Os resultados preliminares deste estudo permitem-nos verificar que a colheita destas espécies de cogumelos pode retirar do sistema 254,01 g/ha de NH4+, 55,98 g/ha de P, 425,73 mg/ha de K, 2,00g/ha de Ca e 11,09 g/ha de Mg, tendo em conta as quantidades de cogumelos colhidos na época estudada.
- Metal composition of table olives from the portuguese market.Publication . Soares, Maria Elisa; Bento, Albino; Bastos, Maria de Lourdes; Pereira, J.A.Olive tree (Olea europaea L.) is one of the most important fruit trees in the Mediterranean countries. Their products, olive oil and also table olives, are important components of the Mediterranean diet and are largely consumed in the world. Table olives are well-known sources of compounds with important biological properties. The preparation of table olives follows three main trades, namely green or Spanish-style olives (Green Olives in Brine - GOB), black ripe or Californian-style olives (Black Ripe Olives), and naturally fermented olives (Direct Brined Olives – DBO). Heavy metals can be present in olive fruits for several reasons: endogenous, depending on the mineral constitution of the soils where the olive trees are located, or exogenous, resulting from the air pollution, contamination by phyto-chemical products and during technological processing. Besides the toxicological characteristics of these elements, the presence of transition metals in these fat matrices can negatively influence the organoleptic and nutritional properties as well as the shelf life of the products.
- Tolerance and bioaccumulation of copper by the entomopathogen Beauveria bassiana (Bals.-Criv.) Vuill. exposed to various copper-based fungicidesPublication . Martins, Fátima; Soares, Maria Elisa; Oliveira, Ivo; Pereira, J.A.; Bastos, Maria de Lourdes; Baptista, PaulaThis work evaluates for the first time the relationships between copper-tolerance, -solubilization and -bioaccumulation in the entomopathogen Beauveria bassiana exposed to Bordeaux mixture, copper oxychloride or copper hydroxide. Bordeaux mixture was highly detrimental to fungus, by inhibiting the growth totally at the recommended dose (RD) and 29RD. Copper hydroxide and copper oxychloride were found to be less toxic, reducing fungus growth, sporulation and conidial germination in an average of 29 %, 30 % and 58 %, respectively. These two copper forms were the easiest to solubilize, to precipitate and the most accumulated by B. bassiana, suggesting the involvement of all these processes on fungus copper-tolerance.
- Tolerance and stress response of Macrolepiota procera to nickelPublication . Baptista, Paula; Ferreira, Sílvia; Soares, Maria Elisa; Coelho, Valentim; Bastos, Maria de LourdesNickel (Ni) is an essential element for many organisms; however, it is very toxic at high concentrations and also depending on the species. In macrofungi the mechanisms underlying their Ni tolerance are poorly documented. This study examines, for the first time, the participation of the antioxidative system in Macrolepiota procera exposed to different Ni2+ concentrations and their relation with Ni tolerance. The effect of the pH on Ni tolerance was also evaluated. The fungus was cultivated on solid medium with different NiCl2 concentrations (0.05, 0.2, 0.8 mM) at pH 4, 6, and 8, and fungi growth and Ni uptake were determined. The antioxidative enzymes catalase (CAT) and superoxide dismutase (SOD) and the production of hydrogen peroxide (H2O2) were evaluated on fungal submerged cultures within the first hours of Ni2+ exposure. Results showed that M. procera growth decreased when Ni2+ concentrations increased, reaching a maximum growth inhibition (>80%) up to 0.2 mM of NiCl2. Ni uptake increased proportionally to Ni increase in the medium. Both Ni tolerance and Ni accumulation were affected by medium pH. Microscope observations showed differences in the size of spores produced by fungi at different Ni concentrations. Ni exposure induced oxidative stress, as indicated by the production of H2O2, the levels of which seem to be regulated by the antioxidant enzymes SOD and CAT. The time variation pattern of SOD and CAT activities indicated that the former has a greater role in alleviating the stress. The results obtained suggested that tolerance of M. procera to Ni2+ is associated with the ability of this macrofungus to initiate an efficient antioxidant defense system
- Tolerance and stress response of the saprobe macrofungi Macrolepiota procera to nickelPublication . Baptista, Paula; Ferreira, Sílvia; Soares, Maria Elisa; Bastos, Maria de LourdesNickel (Ni) is an essential element for many organisms however it is very toxic at high concentrations and also depending on the species. In macrofungi the mechanisms underlying their Ni-tolerance are poorly documented. We examined, for the first time, the participation of the antioxidative system in the Macrolepiota procera exposed to different Ni2+ concentrations and their relation with Ni-tolerance. The effect of the pH on Ni-tolerance was also evaluated. The fungus was cultivated on solid medium with different Ni concentrations (0.05, 0.2, 0.8 mM) at pH 4, 6 and 8, and fungi growth and Ni uptake was determined. The antioxidative enzymes, catalase (CAT) and superoxide dismutase (SOD) and the production of hydrogen peroxide (H2O2) were evaluated on fungal submerged cultures within first hours of Ni exposure. Results showed that M. procera growth decreased when Ni concentrations increased, reaching a maximum growth inhibition (higher than 80%) up to 0.2 mM of Ni. The Ni uptake increased proportionally to Ni increase in the medium. Both Ni-tolerance and Ni-accumulation were affected by media pH. Microscope observations showed differences on the size of spores produced by fungi at different Ni concentration. Ni exposure induced oxidative stress, as indicated by the production of H2O2, which levels seem to be regulated by the antioxidant enzymes SOD and CAT. The time variation pattern of SOD and CAT activities indicated that the first has a greater role on the alleviating stress. The results obtained suggested that the M. procera tolerance to Ni is associated with the ability of this macrofungi to initiate an efficient antioxidant defence system
- A utilização do cobre na protecção fitossanitária da oliveira e implicações na segurança alimentar dos produtos do olival.Publication . Pereira, J.A.; Soares, Maria Elisa; Pavão, Francisco; Bastos, Maria de Lourdes; Bento, AlbinoNa protecção fitossanitária da oliveira, especialmente na luta contra doenças fúngicas, são utilizados pesticidas com diferentes formulações de cobre. A utilização destes produtos e permitida nos diferentes sistemas de protecção do olival, quer seja em produção convencional, em produção integrada ou no modo de produção biológico, o que os torna de utilização praticamente generalizada. Neste sentido, o presente trabalho teve por objectivos estudar a persistência do cobre, aplicado sob diferentes formas - calda bordalesa, hidróxido de cobre e oxicloreto de cobre - em folhas de oliveira e azeitonas durante um período de 44 dias após a aplicação e no azeite obtido em azeitonas processadas em final desse período.