Efeito da temperatura no comportamento reológico de méis colhidos na região nordeste de Portugal

No presente trabalho pretendeu-se estudar o efeito da temperatura sobre as propriedades reológicas de três méis colhidos no nordeste de Portugal. Para isso, analisaram-se dois méis monoflorais - urze e rosmaninho - provenientes do Parque Natural de Montesinho, e um mel polifloral, recolhido na Freguesia de Morais, local de interesse geológico. O comportamento reológico destes méis foi avaliado às temperaturas de 30, 50, 70 e 95 °C. Todos os méis estudados apresentaram um fluxo independente do tempo e a sua maioria comportou-se como um Fluido Newtoniano. Apenas o mel de urze à temperatura de 50 °C e o mel de rosmaninho à temperatura de 95 °C demonstraram ter comportamento de Fluido Pseudoplástico. De entre os méis analisados, o mel de rosmaninho foi aquele que mostrou ser mais sensível à temperatura, apresentando o valor mais elevado de energia de activação (81 ,3 kJ/mol). No que respeita à consistência, o mel pode apresentar-se fluido, espesso ou, parcial ou totalmente cristalizado. Como o mercado, em grande parte, favorece a venda do mel líquido, alguns tipos de tratamento são necessários para manter o mel nesse estado, tais como, a filtração e o aquecimento. O aquecimento é aplicado por inúmeras razões, como por exemplo, para facilitar a sua manipulação e acondicionamento, retardar o fenómeno de granulação e destruir microrganismos que possam estar presentes e que possam alterar negativamente a qualidade do mel. No presente trabalho estudou-se as propriedades reológicas de três méis colhidos no nordeste de Portugal. Dois méis monoflorais – urze e rosmaninho – provenientes do Parque Natural de Montesinho, e um mel polifloral do Sítio de Morais. Como o aquecimento é aplicado para manter o mel em estado líquido e como também é utilizado na preparação de vários pratos culinários, o comportamento reológico desses méis foi analisado às temperaturas de 30, 50, 70 e 95 ºC. Para tal, foi utilizado um viscosímetro de cilindros concêntricos equipado com um controlador de temperatura. Todos os méis estudados apresentaram um fluxo independente do tempo e a sua maioria comportou-se como um Fluido Newtoniano, ou seja, com viscosidade constante. Apenas o mel de urze à temperatura de 50 °C e o mel de rosmaninho à temperatura de 95 °C demonstraram ter comportamento de um Fluido Pseudoplástico. A dependência da viscosidade com a temperatura foi descrita pela equação de Arrhenius, tendo a energia de activação (Ea) variado entre 72,6 e 81,3 KJ/mol. De entre os méis analisados, o mel de rosmaninho foi aquele que mostrou ser mais sensível à temperatura, apresentando o valor mais elevado de Ea (81,3 kJ/mol)

Temperature Effect on Rheological Behavior of Portuguese Honeys

In the present work the temperature effect on rheological properties of Portuguese honeys was studied for the fi rst time. Two unifl oral honeys – heather and rosemary – and a polyfl ower honey were analyzed. All honeys showed fl ow independence over time and behaved as Newtonian fl uids at the studied temperature and shear rate ranges. For all honeys it was found that the viscosity decreased with temperature and the rosemary honey was the one that always presented the lowest viscosity at 30°C (6120 mPa·s), 50°C (603 mPa·s) and 70°C (145 mPa·s). The temperature dependence of viscosity was well described by the T B A K e 0 equation. Nevertheless, good regression coeffi cients were also obtained when fi tting the experimental data to the Arrhenius model, showing the rosemary honey to be less temperature sensitive. The results obtained in this study are of great interest to beekeepers and industrials that handle and prepare eatable honey-based products because they will be better informed about the best type of honey to use.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER under Programme PT2020 for fi nancial support to CIMO (UID/ AGR/00690/2013).info:eu-repo/semantics/publishedVersio

Effect of ultrasound in crude glicerol as pretreatment for methane production

As global energy supply is based on petroleum derivate, scarcity of natural sources and environmental concerns are problems associated to the energy supply as well as the increasing demand. Renewable energy sources can replace this conventional energy source and decrease the environmental emissions.. In this work is going to be evaluated the effect of ultrasound pretreatment on crude glycerol from biodiesel production process to improve the methane production from biogas in an anaerobic digestion process. Different times of pretreatment are going to be examined 10, 15 and 30 minutes to determinate the best performance and compare it to the untreated substrate. The results showed that ultrasound pretreatment improved methane production by using 30 minutes of treatment on crude glycerol.info:eu-repo/semantics/publishedVersio

Effect of stirring and ultrasound assisted extraction conditions in flavonoids, tannins, antioxidant and antimicrobial activities of chestnut outer shells (Castanea sativa Miller)

Portugal is one of the main producersof chestnut in Europe.info:eu-repo/semantics/publishedVersio

Plant and soil metal concentrations in serpentine soils and their influence on the diet of extensive livestock animals

Background: Grazing circuits and resources consumed differ strongly throughout the year and within a territory. For this reason, animals’ diet composition, as well as their exposure to metals, is variable. No studies have been performed on how habitat use affects the metal concentrations to which sheep and goats reared in serpentine soil areas are exposed. Objective: The aim of the present study was to investigate the metal exposure of grazing animals raised in a serpentine soil area of the north-east of Portugal, taking into account the spatial distribution of metal concentrations in soils and plants. Methods: The habitat use and foraging behaviour of six flocks of sheep and goats were studied. The concentrations of Ca, Mg, Mn, Cr and Ni were determined in the soils and plant species most consumed by those animals. Results: The highest Mg, Mn, Cr and Ni concentrations were found in the soils of the ultramafic complex. Ni concentrations above the recommended threshold for agricultural soils (30 μg/g) were found in some sites. A positive correlation between Ni concentration in soils and plants was found (0.634). Ni concentrations higher than 10 μg/g were found in some samples of the following plant species: Sorghum × drummondii (Steud.) Millsp. & Chase,Quercus rotundifolia Lam., Cytisus multiflorus (L’Hér.) Sweet, Cistus ladanifer L. and Erica scoparia L. Significant differences (p ≤ 0.05) in metal concentrations of the plants most consumed by each flock were observed. Conclusion: Grazing circuits have an important role in the metal exposure of animals raised in this serpentine soil area.info:eu-repo/semantics/publishedVersio

Improving water efficiency in a municipal indoor swimming-pool complex: a case study

This study aimed to determine the water demand of a municipal swimming pool complex to propose water use efficiency measures. Concomitantly, the possibility of recycling and reusing the water from filter backwashing was evaluated. The pools consumed 25.6% of water, the filter backwashing 24.5%, and the showers 34.7%. Despite the current impossibility of reducing water consumption in pools and filter backwashing, it is feasible to promote more efficient use of water through reducing water consumption by adopting simple water-saving initiatives for showers, taps, and flushing cisterns. These were organized into three distinct scenarios: (a) flushing cistern volume adjustment and the replacement of washbasin and kitchen taps; (b) flushing cistern volume adjustment and shower replacement and (c) flushing cistern volume adjustment, shower, washbasin, and kitchen taps replacement. Under scenarios 1, 2, and 3, the water consumption reduction was 8.0, 13.2, and 20.4%, respectively. The initial investment for scenario 1 was €2290.5, €859.0 for scenario 2 and €3149.5 for scenario 3; the annual water bill reduction was €7115.4, €11,518.1, and €17,655.9, respectively. Therefore, the turnover of the investment was four (scenario 1), one (scenario 2), and three months (scenario 3). The filter washings attained the required standard for irrigation after being subjected to 15 h of sedimentation.info:eu-repo/semantics/publishedVersio