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High pressure solubility data of carbon dioxide in (tri-iso-butyl(methyl)phosph...
Ventura, Sónia P. M.; Pauly, Jérôme; Daridon, Jean L.; Silva, J. A. Lopes da; Marrucho, Isabel M.; Dias, A. M. A.; Coutinho, J. A. P.Ionic liquids are attracting great attention nowadays due to their interesting properties which make them useful in a broad range of applications including reaction media or separation/capture of environmentally hazardous gases such as carbon dioxide. In many cases, for practical and/or economical reasons, the use of aqueous solutions of ILs would be preferable to their use as pure compounds. In this work, high...
Rheological characterization under shear of a fraction of polymer produced via ...
Pintado, M. E.; Silva, J. A. Lopes da; Pintado, A. I. E.; Malcata, F. X.Production of lactan, a polysaccharide composed of mannose, galactose and galacturonic acid (at the ratio of 5:3:2), starting from a semidefined medium containing lactose via fermentation with Rahnella aquatilis was described previously. In this communication, such polysaccharide was produced from five alternative fermentation media: (1) a synthetic (defined) medium, plain whey (under (2) aerobic and (3) anaero...
Characterization of requeijão and technological optimization of its manufacturi...
Pintado, M. E.; Silva, J. A. Lopes da; Malcata, F. X.In attempts to characterize Portuguese whey cheese (Requeijão) and optimize the manufacture thereof I7 whey cheeses were produced according to a factorial design using heating time, heating temperature and fractional addition of ovinelcaprine milk as manipulated technological variables. Chemical analyses were carried out for the 17 cheeses, whereas sensorial and rheological analyses were carried out for eight s...
Microbiological and rheological studies on Portuguese kefir grains
Pintado, Manuela E.; Silva, J. A. Lopes da; Fernandes, Paulo B.; Malcata, F. Xavier; Hogg, Tim A.Part of the data presented in this paper was included in a poster entitled Studies on kefir grains: microbiological characterization, biomass increase rate, and rheology of the polysaccharide produced, which was presented at the Prof. Nicolau van Uden Portuguese Symposium of Applied Microbiology and Biotechnology – First Symposium on Yeasts, February 1993, Luso, Portugal. ; The native bacteria and yeasts prese...
Kinetics and thermal behaviour of the structure formation process in HMP/sucros...
Silva, J. A. Lopes da; Gonçalves, M. P.; Rao, M. A.The concentration and temperature dependence of the gelation kinetics of high-methoxyl pectin (HMP; 60% sucrose, pH 3) was investigated using measurements of small-amplitude oscillatory shear. The rate of gelation close to the gel point can be described as a second-order rate process using the kinetic model of Ross-Murphy (Carbohydr. Polym. 1991, 14, 281) and a critical exponent close to that predicted by the p...
Influence of temperature on the dynamic and steady-shear rheology of pectin dis...
Silva, J. A. Lopes da; Gonçalves, M. P.; Rao, M. A.The influence of temperature on the dynamic and steady-shear rheology of ionic polysaccharides, high-methoxyl and low-methoxyl pectins, has been studied and compared with the behaviour of locust bean gum, a virtually neutral biopolymer. Using the time-temperature superposition principle, the rheological parameters were reduced to an arbitrary reference temperature. Activation energies were calculated and their ...
Rheological study into the ageing process of high methoxyl pectin/sucrose aqueo...
Silva, J. A. Lopes da; Gonçalves, M. P.The ageing process of high methoxyl pectin (HMP)/sucrose gels was followed at different ageing temperatures by small amplitude oscillatory experiments. Dynamic mechanical measurements allowed the characterisation of the point at which the system undergoes the sol/gel transition. The HMP/sucrose system is extremely sensitive to temperature variation during ageing, especially in the lower temperature range. The v...
Viscoelastic behaviour of mixtures of locust bean gum and pectin dispersions
Silva, J. A. Lopes da; Gonçalves, M. P.; Rao, M. A.Viscoelastic properties of single-component systems — locust bean gum (LBG), high-methoxyl (HMP) and low-methoxyl (LMP) pectins- and of HMP/LBG and LMP/LBG blends, were studied using dynamic oscillatory and steady-shear methods. The mechanical spectra of HMP/LBG blends showed characteristics intermediate between the individual components. A possible weak antagonistic interaction was found between LMP and LBG, e...
Rheological Properties of High-Methoxyl Pectin and Locust Bean Gum Solutions in...
Silva, J. A.Lopes da; Gonçalves, M. P.; Rao, M. A.The Cross and Carreau flow models described well the shear rate-apparent viscosity data. The coil overlap parameter, c[η], correlated well with the zero-shear rate specific viscosities of these mixtures. Experimental values of intrinsic viscosities of the mixtures were in good agreement with the prediction based on an additive model of the individual contributions of the gums. From the results obtained for the ...
Studies on a purification method for locust bean gum by precipitation with isop...
Silva, J.A. Lopes da; Gonçalves, M.P.A commercial sample of locust bean gum was dissolved in hot water, centrifuged, and the supernatant and the sediment were recovered. Part of the supernatant was freeze-dried and the rest was poured into isopropanol to yield a precipitate of purified gum. This precipitate was recovered and a part of it was subjected to a second purification with isopropanol; an almost pure galactomannan sample was obtained. Anot...
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