2008
Authors
Martins, RC; Oliveira, R; Bento, F; Geraldo, D; Lopes, VV; de Pinho, PG; Oliveira, CM; Ferreira, ACS;
Publication
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
Abstract
The development of a fingerprinting strategy capable to evaluate the "oxidation status" of white wines based on cyclic voltammetry is proposed here. It is known that the levels of specific antioxidants and redox mechanisms may be evaluated by cyclic voltammetry. This electrochemical technique was applied on two sets of samples. One group was composed of normal aged white wines and a second group obtained from a white wine forced aging protocol with different oxygen, SO(2), pH, and temperature regimens. A study of antioxidant additions, namely ascorbic acid, was also made in order to establish a statistical link between voltammogram fingerprints and chemical antioxidant substances. It was observed that the oxidation curve presented typical features, which enables sample discrimination according to age, oxygen consumption, and antioxidant additions. In fact, it was possible to place the results into four significant orthogonal directions, compressing 99.8% of nonrandom features. Attempts were made to make voltammogram fingerprinting a tool for monitoring oxidation management. For this purpose, a supervised multivariate control chart was developed using a control sample as reference. When white wines are plotted onto the chart, it is possible to monitor the oxidation status and to diagnose the effects of oxygen regimes and antioxidant activity. Finally, quantification of substances implicated in the oxidation process as reagents (antioxidants) and products (off-flavors) was tried using a supervised algorithmic the partial least square regression analysis. Good correlations (r > 0.93) were observed for ascorbic acid, Folin-Ciocalteu index, total SO(2), methional, and phenylacetaldehyde. These results show that cyclic voltammetry fingerprinting can be used to monitor and diagnose the effects of wine oxidation.
2008
Authors
Silva, JS; Martins, RC; Vicente, AA; Teixeira, JA;
Publication
BIOSIGNALS 2008: PROCEEDINGS OF THE FIRST INTERNATIONAL CONFERENCE ON BIO-INSPIRED SYSTEMS AND SIGNAL PROCESSING, VOL 1
Abstract
UV-VIS spectroscopy is a powerfull qualitative and quantitative technique used in analytical chemistry, which gives information about electronic transitions of electrons in molecular orbitals. As in UV-VIS spectra there is no direct information on characteristic organic groups, vibrational spectroscopy (e.g. infrared) has been preferred for biological applications. In this research, we try to use state-of-the-art fiber optics probes to obtain UV-VIS-SWNIR diffusive reflectance measurements of yeasts and bacteria colonies on plate count agar in the region of 200-1200nm; in order to discriminate the following microorganisms: i) yeasts: Saccharomyces cerevisiae, Saccharomyces bayanus, Candida albicans, Yarrowia lipolytica; and ii) bacteria: Micrococcus luteus, Pseudomonas fluorescens, Escherichia coli, Bacillus cereus. Spectroscopy results show that UV-VIS-SWNIR has great potential for identifying microorganisms on plate count agar. Scattering artifacts of both colonies and plate count agar can be significantly removed using a robust mean scattering algorithm, allowing also better discriminations between the scores obtained by singular value decomposition. Hierarchical clustering analysis of UV-VIS and VIS-SWNIR decomposed spectral scores lead to the conclusion that the use of VIS-SWNIR light source produces higher discrimination ratios for all the studied microorganisms, presenting great potential for developing biotechnology applications.
2008
Authors
Sabugosa-Madeira, B; Ribeiro, H; Cunha, M; Abreu, I;
Publication
Journal of Apicultural Research
Abstract
2008
Authors
Brinckmann, J; Dele, R; Goffin, R; Kinsch, P; Thillen, G; Cunha, M;
Publication
ANNALS - 3rd International Meeting on Ironmaking and 2nd International Symposium on Iron Ore
Abstract
The Paul Wurth Bell-Less Top® (BLT) is the industrial standard for iron blast furnace charging systems. Since Paul Wurth's invention of the BLT in the early 1970s the system has evolved with the changes in iron-making technologies and market conditions. With the latest demands for high charging equipment availability and maintainability - new developments have been recently implemented. The paper will cover the evolution of the Bell-Less Top®, the latest operational requirements and the latest new developments and solutions.
2008
Authors
Ribeiro, H; Cunha, M; Abreu, I;
Publication
AEROBIOLOGIA
Abstract
In this work the objective was to develop a bioclimatic model to forecast olive yield based on airborne pollen, soil water content, and favourable conditions for phytopathological attacks. Olive airborne pollen was sampled from 1998 to 2006 using Cour traps installed in the Tras-os-Montes e Alto Douro region, in the provinces of Valenca do Douro and Vila Nova de Foz-Coa. Meteorological data from a meteorological station located in Pinhao, near the pollen samplers, was used to calculate other independent variables. According to the bioclimatic model, at the flowering stage 63% of regional olive production can be predicted from the regional pollen index, with an average deviation between observed and predicted production of 10%. The variable soil water content enabled an increase in forecasting accuracy of about 30%, and a reduction in the average deviation between observed and predicted production of 6%. The final regression with all three variables tested showed that the bioclimatic model was able to predict the annual variability of regional olive fruit production with an accuracy of 97%, the average deviation between observed and predicted production being 3% for internal validation and 6% for external validation.
2008
Authors
Sabugosa Madeira, B; Ribeiro, H; Cunha, M; Abreu, I;
Publication
PROCEEDINGS OF THE SECOND IBERIAN CONGRESS ON CHESTNUT
Abstract
The impact of climatic changes can be evaluated by analysing the long-trends of plant phenological events. The airborne pollen sampling and the study of Apis mellifera L. (honeybee) collected pollen are two methodologies that can be used to survey the date of occurrence of the flowering phase. The aim of the present work was to compare the anemophilous and entomophilous pollen flows of Castanea sativa (chestnut tree) in two regions of the north-west of Portugal. The synchronism between the airborne samples and the honeybee samples was confirmed by the significant positive correlation between them. The inter-annual variations in the beginning and peak dates of pollen flows were very similar although an anticipation was observed in the honeybees.
The access to the final selection minute is only available to applicants.
Please check the confirmation e-mail of your application to obtain the access code.