Browsing by Author "Barroca, M J"
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- Chemical composition of Ruscus aculeatus L. – Preliminary StudiesPublication . Dulyanska, Y; Cruz-Lopes, Luísa; Esteves, Bruno; Barroca, M J; Carvalho, L; Gonçalves, Fernando Jorge; Domingos, Idalina; Ferreira, José; Guiné, Raquel P. F.
- Effect of drying on the physical properties of quincePublication . Guiné, Raquel; Barroca, M JThis study aimed at evaluating the textural properties of quince in fresh and after drying at different conditions. In parallel, colour was also measured to evaluate how the visual aspect of the product changed with drying. The experiments were done in a tunnel drier, at different temperatures, from 30 to 60ºC, and different air velocities, varying in the range 0.7 to 1.2 m/s. The colour coordinates of the fresh quince were: L* = 78.02±0.86, a* = - 1.27±0.32 and b* = 31.75±1.68. These values indicate that the samples were bright, because L* was closer to 100 than to 0. Furthermore, it can be seen that quince was greenish, although very slightly and strongly yellowish. With drying, the samples became darker and redness was intensified, as a result of browning. In relation to the textural properties in fresh, the values were: hardness = 48.46±6.47 (N), springiness = 74.86±5.17 (%), cohesiveness = 0.75±0.06, resilience = 0.47±0.08 and chewiness = 27.23±4.06 (N). Furthermore, it was observed that drying, regardless of the conditions, induced an important hardening, increasing hardness and diminishing springiness.
- Evaluation of browning rate of quince at ambient exposurePublication . Guiné, Raquel; Barroca, M JSince quince is a fruit relatively susceptible to browning, in the present work it was evaluated the colour of the quince over time of exposure to the atmospheric air. The colour of the fresh pulp was assessed using a handheld tristimulus colorimeter using the CIELab colour coordinates: L*a*b*. These Cartesian coordinates were then used to calculate the polar or cylindrical coordinates: value, hue angle (º) and chroma. At each instant, ten measurements of colour were made, and to evaluate the colour change, measurements were repeated in the same samples after every 5 minutes, over a period of two hours. The results obtained for the medium values of the cylindrical coordinates in the freshly cut quince were found to be: value = 7.80, chroma = 31.78 and Hue = 92.28º, being these values determined right after cutting. Total colour difference (TCD) was calculated having the values of the Cartesian coordinates of the freshly cut quince as reference. In relation to the colour change, the values for TCD were 0.00, 26.35, 30.41, 31.81 and 32.39, respectively for times 0, 30, 60, 90 and 120 minutes, indicating a faster rate initially and a tendency for stabilization towards the end of the period analyzed.
- Liquefaction optimization of Crataegus monogyna JacqPublication . Dulyanska, Y; Cruz-Lopes, Luísa; Esteves, Bruno; Domingos, Idalina; Ferreira, José; Guiné, Raquel; Gonçalves, Fernando Jorge; Carvalho, L B; Barroca, M JThe objective of this work was to evaluate the potentiality of Crataegus monogyna Jacq. residues to be liquefied by polyhydric alcohols and the chemical transformations observed in this process with subsequent use to produce polyurethane foams. The variations on liquefaction yield were determined at different temperature, time, material/solvent ratio and granulometry. Results show that liquefaction performed at 180 °C with a 1:10 material/solvent ratio increases along time, reaching a maximum at 60 min. Similarly, liquefactions made during 60 min with a 1:10 material/solvent ratio show that there is an increase in liquefaction yield with the increase in temperature until 180 °C. A higher temperature could increase the liquefaction yield but would lead to a higher energy consumption in the process. There seems to be no significative advantage in increasing material/solvent ratio above 1:7, although the liquefaction yield increases for higher ratios. Granulometry testing shows that the smaller the particle the best is the liquefaction percentage. It was concluded that the best liquefaction yield, of approximately 81%, was obtained with a temperature of 180 °C, for 60 min and particle size <80 mesh for Crataegus monogyna Jacq. This material has good properties to be converted in a liquid mixture that can be used later, on the production of polyurethane foams.
- Sea Purslane as an Emerging Food Crop: Nutritional and Biological StudiesPublication . Pires, A; Agreira, S; Ressurreição, S; Marques, J; Guiné, Raquel; Barroca, M J; Silva, A MHalophyte plants are highly adapted to salt marsh ecosystems due to their physiological and ecological characteristics. Halimione portulacoides (L.) Aellen is one abundant halophyte shrub that belongs to a Chenopodiaceae family and Caryophyllales order and is found on sandy or muddy coastlines and salt marshes. In this study, the leaves of sea purslane (H. portulacoides) grown in Figueira da Foz (Portugal) were characterized at nutritional and mineral concentration. Moreover, different methanolic extracts were obtained from the leaves, and the antioxidant activity was assessed by several methods. From a nutritional point of view, this halophyte plant may be considered a good source of dietary fiber, protein, natural minerals such as calcium, magnesium, manganese, copper, and potassium. The primary sugar found in leaves of sea purslane is maltose, followed by sucrose, glucose, and fructose. Finally, leaves showed a high content of phenolic compounds and considerable antioxidant activity. The novel products butter and pasta enriched with powder dried leaves of H. portulacoides revealed the plant’s potential to be used as a salt substitute and a good alternative to enhance the sensory characteristics of products, with additional health benefits. The nutritional characteristics and the phytochemical value highlight H. portulacoides as a potential candidate crop in saline agriculture and to be used as a new vegetable, especially as a premium food in the novel “salty veggies” market or as a kitchen salt substitute.