Universidade de Coimbra
Departamento de Engenharia Química
The present study aims to analyse the evolution of colour and browning of fortified wines submitted to oak and accelerated ageing induced by temperature, both traditional ageing processes of Madeira wines. These wines were followed during... more
The present study aims to analyse the evolution of colour and browning of fortified wines submitted to oak and accelerated ageing induced by temperature, both traditional ageing processes of Madeira wines. These wines were followed during the first 2 years of ageing and were simultaneously compared to aged reference samples, in order to disclose if accelerated ageing favours the wine evolution. The data analysis approaches followed two strategies: the first one was based on the monitoring of wine colour parameters based on CIELab methodology, while the second strategy adopted an untargeted approach, taking advantage of all wine information comprised on the UV-vis spectrum. CIELab results indicated that the greatest variation (up to 92 %) occurs during the vinification, since it was observed that wines produced from the same grape variety (Tinta Negra) acquired different characteristics already on the vinification processes. All wines tend to approach the reference samples during ageing, with the lowest ΔE* value obtained for Malvasia submitted to canteiro at 2 years of ageing (3.29 units). Sweet Tinta Negra wines, previously submitted to estufagem, presented the most pronounced colour change associated with ageing. The multivariate principal component analysis (PCA) model was built with aged reference samples to evaluate how young wines acquire the reference wine’s characteristics and revealed that accelerated ageing increases colour evolution and favours the homogeneity of Malvasia wines.
- by Maria João Carvalho and +4
- •
- Food Chemistry
h i g h l i g h t s
A systematization of complex data structures, originated in current processes and product analysis activities, is presented as a starting point for developing generalized and flexible frameworks for handling such challenging information... more
A systematization of complex data structures, originated in current processes and product analysis activities, is presented as a starting point for developing generalized and flexible frameworks for handling such challenging information sources. In this article, we present an abstract and unifying definition for a class of multidimensional data arrays (here called profiles), built upon which a taxonomy is proposed for their classification, according to aspects relevant for the development of software platforms, namely, the underlying data structure characteristics and the nature of information they convey. Such taxonomy is based on an extensive bibliographic review involving the analysis of complex datasets. Then, we identify the classes of profiles with higher demand (dominant classes) and, for these, conduct a comparison study involving those methodologies that could be applied in the context of two tasks: calibration/regression and process monitoring. The comparison study showed that the Tucker3 and N-way Partial Least Squares methods are good candidates to incorporate a computational framework addressing the dominant classes of profiles that were identified.
The current study was focused on the impact of accelerated ageing (heating step) on the amino acid and biogenic amine profiles of fortified wines. In this sense, three Madeira wines from two commonly used grape varieties (one red and the... more
The current study was focused on the impact of accelerated ageing (heating step) on the amino acid and biogenic amine profiles of fortified wines. In this sense, three Madeira wines from two commonly used grape varieties (one red and the other white) were analysed during the heating, at standard (45 ∘ C, 3 months) and overheating (70 ∘ C, 1 month) conditions, following a precolumn derivatization procedure using iodoacetic acid, o-phthaldialdehyde, and 2-mercaptoethanol, carried out in the injection loop prior to RP-HPLC-FLD detection. Eighteen amino acids were identified, with arginine being the most abundant. An important decrease of the amino acid levels was detected during the standard heating (up to 30%), enhanced up to 61% by the temperature increase. Cysteine, histidine, and asparagine revealed the greatest decreases at 45 ∘ C. Conversely, some amino acids, such as asparagine, slightly increased. Four biogenic amines were identified but always in trace amounts. Finally, it was observed that the accelerated ageing did not favour the biogenic amine development. The results also indicate that the heating process promotes the amino acid transformation into new ageing products.
Folha 2-Cinemática 1/8 1. Uma partícula move-se com movimento retilíneo segundo a lei = 2 + 5 + 5, em unidades SI. a) Calcular a velocidade e a aceleração da partícula num instante. b) Calcular a velocidade média e a aceleração média da... more
Folha 2-Cinemática 1/8 1. Uma partícula move-se com movimento retilíneo segundo a lei = 2 + 5 + 5, em unidades SI. a) Calcular a velocidade e a aceleração da partícula num instante. b) Calcular a velocidade média e a aceleração média da partícula, entre = 2 s e = 3 s. 2. A aceleração de uma partícula com movimento retilíneo é definida pela expressão = 6 m/s 2. Sabendo que no instante inicial = 0 a partícula se encontra na posição = −32 m e que no instante = 2 s a sua velocidade é = −6 m/s, determinar a posição e a velocidade da partícula em função do tempo. Qual o deslocamento e o espaço percorrido pela partícula entre os instantes = 0 e = 5 s? 3. A aceleração de uma partícula com movimento retilíneo é diretamente proporcional ao tempo. No instante inicial = 0 a velocidade da partícula é = 16 m/s. Sabe-se que = 15 m/s e = 20 m quando = 1 s. Determinar as expressões da posição e da velocidade da partícula em função do tempo. Qual o deslocamento e o espaço percorrido pela partícula entre os instantes = 0 e = 7 s? 4. A aceleração de uma partícula com movimento retilíneo é diretamente proporcional ao quadrado do tempo. No instante inicial = 0 a partícula encontra-se na posição = 24 m. Sabe-se que = 96 m e que = 18 m/s quando = 6 s. Determinar as expressões da posição e da velocidade da partícula em função do tempo. 5. A aceleração de uma partícula com movimento retilíneo é definida pela expressão = − 6 , em unidades SI, sendo uma constante. Sabendo que no instante = 0 a partícula tem velocidade nula e que em = 1 s a velocidade é de 30 m/s, determinar: a) Os instantes para os quais a velocidade é nula. b) O deslocamento entre os instantes = 1 s e = 7 s. 6. Um objeto é atirado na vertical, para cima, com uma velocidade de 30 m/s. a) A que altura se encontra o objeto e qual a sua velocidade 4 segundos depois do lançamento? b) Qual a altura máxima atingida pelo objeto? c) Passado quanto tempo retorna o objeto ao ponto de partida e qual a sua velocidade nesse instante? 7. Um motorista conduz um automóvel à velocidade de 72 km/h quando avista uma árvore caída no pavimento. Considere que o motorista teve um tempo de reação de 0,7 segundos e que travou comunicando ao automóvel uma aceleração constante com módulo de 5 m/s 2. a) Que distância percorreu o veículo durante o tempo de reação? b) Calcular a distância a que o automóvel estava da árvore quando o motorista a avistou, considerando que o automóvel se imobilizou a 4 metros da árvore. 8. Uma partícula é lançada com velocidade inicial de módulo e com aceleração constante de módulo , movendo-se em linha reta. No instante em que a velocidade escalar atinge 5 , a aceleração muda de sentido, mantendo o seu módulo inalterado. Determinar a velocidade com que a partícula volta a passar pelo ponto de partida.
- by Maria Duarte
- •
The use of livestock guarding dogs for wolf conservation in Portugal. First results In Portugal the Iberian wolf is in danger of extinction, due essentially to man's persecution. Economic losses caused by wolf predation on livestock, its... more
The use of livestock guarding dogs for wolf conservation in Portugal. First results In Portugal the Iberian wolf is in danger of extinction, due essentially to man's persecution. Economic losses caused by wolf predation on livestock, its primary food resource, is the main cause for the conflict. This project has two important goals:-To contribute to the decrease of wolf predatory impact on livestock, by flock protection with autochthonous livestock guarding dog breeds-Castro Laboreiro Watchdog and Estrela Mountain dog.-To use this kind of flock protection as an innovative tool for wolf conservation. The project has started in 1997, will last three years and comprise three phases. The information collected on the first phase will allow the selection of shepherds and dogs that will be used in the project. Genetic variability will be analysed on both dog breeds. On the second phase the efficiency of dogs as livestock guards will be tested and demonstrated on pilotflocks from the Northeast and Centre of Portugal. The disclosure divulgation and spreading of this conservative measure will take place during the third phase. The results regarding the analysis of genetic variability are still preliminary data.
- by José Matos
- •