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- Produção diferencial de compostos voláteis em caules de Pinus pinaster inoculados com o nemátode da madeira do pinheiro (Bursaphelenchus xylophilus)Publication . Lima, Marta R. M.; Ferreira, António C. Silva; Vasconcelos, Marta W.
- Contribution of wild strains of lactic acid bacteria to the typical aroma of artisanal cheesePublication . Tavaria, Freni; Ferreira, A. César Silva; Malcata, F. Xavier
- Kinetics of oxidative degradation of white wines and how they are Affected by selected technological parametersPublication . Ferreira, António César Silva; Pinho, Paula Guedes de; Rodrigues, Paula; Hogg, TimThe negative effects of oxygen on white wine quality and the various factors which influence it (including temperature, dissolved oxygen, pH, and free SO2) are well documented both at the sensory and compositional levels. What is less defined is the quantitative relationship between these parameters and the kinetics of the development of the negative effects of oxidation. The experiment presented here attempts to generate data which can be used to predictively model the oxidative degradation of white wines. Bottled wines were submitted to extreme conditions (45 °C temperature, O2 saturation) during 3 months witth samples taken every 15 days for both sensorial and chemical analysis (GC-O/FPD/MS, 420 nm). The synergistic effects of increasing temperature and O2 at lower pH are evident, both on the decrease in levels of terpene alcohols and norisoprenoids (which impart floral aromas), and on the development of off-flavors such as “honey-like”, “boiled-potato”, and “farmfeed” associated with the presence of phenylacetaldehyde, methional, and 1,1,6-trimethyl-1,2- dihydronaphthalene.
- Determination of carotenoid profiles in grapes, musts, and fortified wines from Douro varieties of vitis viniferaPublication . Pinho, Paula Guedes de; Ferreira, António C. Silva; Pinto, Manuela Mendes; Benitez, Juan Gomez; Hogg, Timβ-Carotene and six xanthophylls (lutein, neoxanthin, violaxanthin, luteoxanthin, cryptoxanthin, and echinenone) have been identified and semiquantitatively or quantitatively determined in musts and port wines for the first time. An HPLC method was developed and compared with that of one based on thin layer cromatography with scanning densitometry. The most abundant carotenoids present in red grape varieties are β-carotene and lutein. In wines, significant quantities of violaxanthin, luteoxanthin, and neoxanthin were found. This study was done with berries (skin and pulp), musts, and fortified wines. Some experiments were performed to follow carotenoid content from grapes to wines. Although the levels of β-carotene and lutein found in fortified wines were lower than those found in musts, other xanthophylls, such as neoxanthin, violaxanthin, and luteoxanthin, exist in appreciable amounts in young ports.
- Development of an immunoassay for ciprofloxacin using phage-displayed antibody fragmentsPublication . Gomes, Francisco Brás; Riedstra, Symon; Ferreira, A. C. Silva; Ferreira, João Paulo M.
- Madeira wines: sensory impact of two production procedures on the “typical character” of malvasia and sercial winesPublication . Machado, B. P.; Pinho, P. Guedes de; Ferreira, A. C. Silva
- Chemiomics: network reconstruction and kinetics of Port Wine agingPublication . Monforte, Ana Rita; Jacobson, Dan; Ferreira, A. C. SilvaNetwork reconstruction (NR) has proven to be useful in the detection and visualization of relationships among the compounds present in a Port wine aging data set. This view of the data provides a considerable amount of information with which to understand the kinetic contexts of the molecules represented by peaks in each chromatogram. The aim of this study was to use NR together with the determination of kinetic parameters to extract more information about the mechanisms involved in Port wine aging. The volatile compounds present in samples of Port wines spanning 128 years in age were measured with the use of GC-MS. After chromatogram alignment, a peak matrix was created, and all peak vectors were compared to one another to determine their Pearson correlations over time. A correlation network was created and filtered on the basis of the resulting correlation values. Some nodes in the network were further studied in experiments on Port wines stored under different conditions of oxygen and temperature in order to determine their kinetic parameters. The resulting network can be divided into three main branches. The first branch is related to compounds that do not directly correlate to age, the second branch contains compounds affected by temperature, and the third branch contains compounds associated with oxygen. Compounds clustered in the same branch of the network have similar expression patterns over time as well as the same kinetic order, thus are likely to be dependent on the same technological parameters. Network construction and visualization provides more information with which to understand the probable kinetic contexts of the molecules represented by peaks in each chromatogram. The approach described here is a powerful tool for the study of mechanisms and kinetics in complex systems and should aid in the understanding and monitoring of wine quality.
- Contribution of wild strains of lactic acid bacteria to the typical aroma of artisanal cheesePublication . Tavaria, Freni; Ferreira, A. César Silva; Malcata, F. XavierVolatile fatty acids (VFAs) are major contributors to the aroma profile of Serra da Estrela cheese. The impact of the dominant VFAs to the overall aroma perception was evaluated in a sensory test by a panel. The contribution of wild strains of lactic acid bacteria isolated from mature Serra da Estrela cheese to its volatile free fatty acid profile was also assessed. For this purpose, experimental cheeses manufactured according to the traditional protocol, but specifically added with starter cultures were analysed. Cheeses manufactured with deliberate inclusion of Lactobacillus plantarum as adjunct possessed aroma characteristics essentially similar to those manufactured artisanally, but with higher amounts of VFAs ─ thus meaning that this strain may help reduce ripening time in this cheese variety.
- Study of quinones reactions with wine nucleophiles by cyclic voltammetryPublication . Oliveira, Carla. M.; Barros, António S.; Ferreira, António César Silva; Silva, Artur M. S.Quinones are electrophilic species which can react with various nucleophiles, like wine antioxidants, such as sulfur dioxide or ascorbic acid, thiols, amino acids, and numerous polyphenols. These reactions are very important in wine aging because they mediate oxygen reactions during both production and bottle aging phases. In this work, the major challenge was to determine the interaction between ortho-quinones and wine nucleophiles (amino acids, thiols, and the antioxidants SO2 and ascorbic acid), by cyclic voltammetry. Wine-model solutions with gallic acid, caffeic acid, or (+)-catechin and nucleophilic compounds were used. To understand the effect of nucleophilic addition in wine, a white wine with the same added nucleophiles was also analysed. Cyclic voltammograms were taken with glassy carbon electrode or screen-printed carbon electrodes, respectively, for wine-model and white wines solutions, in the absence and in the presence of nucleophiles. A nucleophilic order profile related to the cathodic current intensity decrease was observed.
- Sphingobium vermicomposti sp. nov., isolated from vermicompostPublication . Vaz-Moreira, Ivone; Faria, Cátia; Lopes, Ana R.; Svensson, Liselott; Falsen, Enevold; Moore, Edward R. B.; Ferreira, António C. Silva; Nunes, Olga C.; Manaia, Célia M.Strain VC-230T was isolated from homemade vermicompost produced from kitchen waste. The isolate was a Gram-negative-staining, catalase- and oxidase-positive, motile rod-shaped bacterium able to grow at 15–37 6C and pH 6–8. On the basis of 16S rRNA gene sequence analysis, strain VC-230T was determined to belong to the family Sphingomonadaceae by its clustering with type strains of the genus Sphingobium, with Sphingobium chlorophenolicum ATCC 33790T (97.7 %) and Sphingobium herbicidovorans DSM 11019T (97.4 %) as its closest neighbours. The polar lipid pattern, the presence of spermidine and ubiquinone 10, the predominance of the cellular fatty acids C18 : 1v7c/9t/12t, C16 : 1v7c and C16 : 0 and the G+C content of the genomic DNA supported the affiliation of this organism to the genus Sphingobium. The phylogenetic, chemotaxonomic, phenotypic and DNA–DNA hybridization analyses verify that strain VC-230T represents a novel species, for which the name Sphingobium vermicomposti sp. nov. is proposed. The type strain is VC-230T (5CCUG 55809T 5DSM 21299T).