Percorrer por autor "Dias, Alberto"
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- Analysis and quantification of flavonoidic compounds from Portuguese olive (Olea europeae L.) leaf cultivarsPublication . Meirinhos, Julieta; Silva, Branca M.; Valentão, Patrícia; Seabra, Rosa M.; Pereira, J.A.; Dias, Alberto; Andrade, Paula B.; Ferreres, FredericoTwenty three samples of 18 Portuguese olive leaf cultivars were analysed by a reversed-phase HPLC/DAD procedure and eight flavonoidic compounds were identified and quantified (luteolin 7,40-O-diglucoside, luteolin 7-O-glucoside, rutin, apigenin 7-O-rutinoside, luteolin 40-O-glucoside, luteolin, apigenin and diosmetin). Luteolin 7,40-O-diglucoside and luteolin 40-O-glucoside were identified by HPLC/DAD/MS/MS – ESI. The studied olive leaf samples showed a common phenolic pattern, in which luteolin 40-O-glucoside was almost always the major compound
- Development of a highly sensitive real-time PCR system for the quantification of soybean as a potential allergenic ingredientPublication . Dias, Alberto; Costa, Joana; Amaral, Joana S.; Oliveira, Beatriz; Mafra, IsabelSoybean is a food ingredient with both techno- and biofunctionality properties, whose use has been increasing considerably in the past decades [I]. Besides its numerous applications, soybean is widely used by the food industry in processed foodstuffs such as sausages, hamburgers or hams. However, since soybean is considered one of the most common foods known to cause allergic reactions in sensitized individuais, the European Union established legislation aiming to protect these patients According to the Directive 2007/68/EC, soybean plus 13 other groups of foods must always be labeled independently of its amount For labeling compliance monitoring, the development ofadequate methodology for soybean detection is ofutmost importance In this work, we propose developing a molecular approach based on real-time polymerase chain reaction (PCR) system with adequate sensitivity for the quantitative analysis of soy as a potential aliergen in meat products. For this purpose, different model samples of pork meat spiked with known amounts of isolated or concentrated soy protein, ranging from 10% to O 00 I %, with and without heat treatment were prepared. The reference mixtures were used to develop a calibration model based on real-time PCR using primers and hydrolysis probes specifically designed to target eukaryotic reference (universal) and lectin (specific for soybean) genes.
- Flavonóides em folhas de cultivares portuguesas de oliveira.Publication . Meirinhos, Julieta; Silva, Branca M.; Valentão, Patrícia; Seabra, Rosa M.; Pereira, J.A.; Dias, Alberto; Andrade, Paula B.; Ferreres, Frederico
- In vitro culture conditions of Colletotrichum gloeosporioides for spore production: a) Effect of medium composition and light on spore productionPublication . Offerman, J.; Sousa, Maria João; Rodrigues, Paula; Martins, Anabela; Dias, AlbertoColletotrichum gloeosporioides, the imperfect stage of the ascomycete Glomerella singulata, is responsible for anthracnose in a wide variety of plant species. Hypericum perforatum, which is responsible for the synthesis of hypericin, a metabolite with important pharmaceutical applications, is one of the species sensitive to C. gloeosporioides. Since H. perforatum tolerance to C. gloeosporioides is dependent on plant variety, we intend to select tolerant varieties in vitro for metabolite production without fungicide application. C. gloeosporioides spores are needed to inoculate and induce a selective pressure on plants, but in vitro sporulation is particularly difficult to achieve. The establishment of in vitro conditions for sporulation was the main goal of the trials here presented. Two variables were tested for C. gloeosporioides spore production: medium composition and light. The effect of medium composition was tested by growing the fungus in PDA (Potato Dextrose Agar) and MMN (modified Melin & Norkrans). We also tested the influence of moving the fungus from PDA to MMN and vice-versa. Growth and spore formation was recorded for a period of three months. Light influence was tested by submitting the fungus to light and dark conditions, for both media. Growth and spore formation under these conditions was recorded for a period of two months. Preliminary results showed PDA to be a better medium for spore production in C. gloeosporioides. The presence or absence of light did not influence spore production.
- In vitro culture conditions of colletotrichum gloeosporioides: b) Effect of temperature shock on spore productionPublication . Offerman, J.; Sousa, Maria João; Rodrigues, Paula; Martins, Anabela; Dias, AlbertoHypericum perfuratum is an important plant species used for the production of hypericin, a metabolite of major application in the pharmaceutical industry. Its production is, however, strongly limited by Colletotrichum gloeosporioides, the causative agent of anthracnose. As H. perforatum tolerance to C. gloeosporioides is dependent on plant variety, we intend to select tolerant varieties under in vitro conditions for metabolite production without fungicide application. Selective pressure on plants is induced by inoculation with the fungus spores, but spores are difficult to obtain. The establishment of in vitro conditions for spore production was the main goal of the trials here presented. The influence of changing temperature on spore production of C. gloeosporioides was tested. Four different temperature conditions were tested, using the environment temperature as reference. We tested the influence of an initial cold and heat shock, as well as a cold and heat shock after growth under environment conditions. Preliminary results showed that an initial heat shock induces spore production in C. gloeosporioides. Complementary trials on spore production and in vitro plant inoculation are being developed.
- Leguminous cover crops improve the profitability and the sustainability of rainfed olive (Olea europaea L.) orchards: from soil biology to physiology of yield determinationPublication . Correia, Carlos M.; Brito, Cátia; Sampaio, A.; Dias, Alberto; Bacelar, Eunice; Gonçalves, Berta C.C.; Ferreira, Helena; Moutinho-Pereira, José; Rodrigues, M.A.The olive sector has a crucial economic, social, cultural and ecological relevance in the Mediterranean region, where tillage and herbicides application still are generalized practices. However, these techniques oppose to the recommendations of UE policy. Thus, other methods are needed to reduce adverse environmental impacts and to improve biodiversity, soil carbon sink and fertility, to save fossil fuels and to increase yield and the safety and nutritional value of food products. Meanwhile, since Mediterranean basin is particularly vulnerable to climate change, including lower precipitation in summer, olive tree will experiment some hard changes, mainly under rainfed conditions. Therefore, we propose an adequate management of cover crops to shift tillage and herbicides, in order to minimize runoff and evaporation water losses, conserve soil moisture storage and promote the infiltration of water in soil. The experiment was carried out during 4 years on a commercial orchard (cv. Cobrançosa) in Northeast Portugal. The treatments laid out were: (1) ordinary tillage techniques (OT) used by local growers (two tillage trips per year); (2) cover crop with self-reseeding annual legume species (AL); (3) natural vegetation fertilized (NVF) with 60 kg N hm2 (as in OT); (4) natural vegetation (NV) left unfertilized. The results revealed that AL treatment is the best option, reaching 37, 53 and 95% higher cumulative yield than NVF, OT and NV, respectively, in a closely association with greater physiological performance during the summer, mainly evidenced by lower oxidative damage and by favourable changes in water status and net photosynthetic rate, due to lower stomatal and mesophyll limitations. Moreover, the AL covered soil presented considerable microbial diversity and enzymatic activities, which may contribute to promote and conserve soil quality and health, as well the stability of ecosystems. Thus, leguminous cover crops improve the profitability and the sustainability of rainfed olive orchards.