| 1. |
- da Cruz Francisco, José, et al.
(författare)
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Gelatinization of cassava, potato and wheat starches in supercritical carbon dioxide
- 2002
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Ingår i: Journal of Supercritical Fluids. - 0896-8446. ; 22:3, s. 247-254
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Tidskriftsartikel (refereegranskat)abstract
- The gelatinization of cassava, potato and wheat starches in supercritical carbon dioxide was investigated using light microscope. The starch was placed in a stainless steel chamber at atmospheric pressure and high CO2 pressures, 8 and 30 MPa as well as at 8 MPa N-2 and the gelatinization degree observed by light microscopy. The results showed that both pressure and supercritical fluid affected the gelatinization degree. Cassava and potato starches showed a lowering of the gelatinization temperatures at 8 MPa and an increasing at 30 MPa as compared with the gelatinization degree at atmospheric pressure. For wheat starch, the decrease in the gelatinization temperature occurred in the same direction as the pressure increased, in comparison with the atmospheric pressure conditions. However, between the two applied pressures, there was a larger increase of the gelatinization temperature at 30 MPa than at 8 MPa. The effect of hydrostatic pressure component of the CO2 was evaluated by using N-2 at 8 MPa. The replacement of CO2 by N-2 at 8 MPa increased the gelatinization temperature for all the studied starches compared with the atmospheric conditions. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 2. |
- da Cruz Francisco, José
(författare)
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On the Extraction of Essential Oils by Supercritical Carbon Dioxide and its Influence on the Mesomorphic Phase Structures
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A comparison of essential oils from leaves of Eucalyptus camaldulensis Dehn. obtained by hydrodistillation (HD) and supercritical carbon dioxide (SC-CO2) extraction is presented. Selected major components of the oils showed a predominance of higher molecular weight components in the SC-CO2 extracts than in those obtained by HD. Physico chemical properties such as molecular weight, vapour pressure of the components, steric factor as well as in oil composition. Discussions on environmental effects on the quality of the essential oils obtained on the same eucalyptus genotype treated by the same techniques are also presented. The monoterpenes 1,8-cineole, limonene and a-pinene, present in considerable amounts in eucalyptus leaf oils, as well as their mixtures and three eucalyptus oils from different genotypes, namely E. dives, E. polybractea and E. radiata, were also studied with regard to their solubility in dense CO2 (SC-CO2 and LCO2). In general, pure compounds showed a higher solubility in SC-CO2. The composition SC-CO2 at the highest pressure and temperature. Since polar lipids are always present in eucalyptus leaves from which the oil is extracted, the interaction between such lipids, water, SC-CO2 and essential oils is important to study. First, liquid crystalline properties and the extractability of monoolein/water systems by supercritical carbon dioxide are discussed. The most remarkable observation in this study was the loss of the native mesomorphic structure at high temperatures and the low recovery of monoolein in monoolein/water systems within the highest (18wt%) water content at temperatures between 35 and 65°C. These effects are explained by the SC-CO2, water and monoolein interactions which lead to different water and monoolein activities in the phase present. Further, two model systems composed of monoolein/water or soybean lecithin/water, cineole and SC-CO2 are presented for studying the phase behaviour. Generally, it is observed that the liquid crystalline structure remain also in presence of surplus of SC-CO2. Hence, it can be assumed that lipid structures in the plant tissues may remain also during SC-CO2 extraction and contribute to the matrix effects observed in extraction trials.
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| 3. |
- da Cruz Francisco, José, et al.
(författare)
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Phase behavior of the monoolein-water system - The effects of addition of the hydrocarbon 1,8-cineole and supercritical carbon dioxide
- 2004
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Ingår i: Journal of Supercritical Fluids. - : Elsevier BV. - 0896-8446. ; 31:3, s. 263-271
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Tidskriftsartikel (refereegranskat)abstract
- The results of a study on the phase behavior of the monoolein/water system with the addition of the hydrocarbon 1,8-cineole (C10H18O) and supercritical carbon dioxide at 15 MPa is presented. To two mixtures consisting of 9 and 18 wt.% water in monoolein, 5, 10, and 20 wt.% cineole were added and heated to between 35 and 80 degreesC at atmospheric pressure and in the presence of supercritical carbon dioxide. The phase changes were followed by deuterium nuclear magnetic resonance (H-2 NMR), light microscopy, and ocular inspection. The mesomorphic structures developed in the 9 wt.% water sample suffered little change due to the presence of the supercritical carbon dioxide. However, in the mixture with 18 wt.% water, the native phase structures were dramatically affected and an isotropic fluid phase developed. The addition of cineole has lowered the LC-L-alpha --> LC-H-Pi phase transition in the samples with 9 and 18 wt.% water in monoolein. The surplus of supercritical carbon dioxide in the samples has resulted in similar developments. Regardless of the amount of cineole present in the system, only the isotropic fluid phase was observed in the samples with 18 wt.% water in monoolein. (C) 2004 Elsevier B.V. All rights reserved.
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| 4. |
- da Cruz Francisco, José, et al.
(författare)
-
Phase behavior of the system lecithin-water - The effects of addition of the hydrocarbon 1,8-cineole and supercritical carbon dioxide
- 2004
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Ingår i: Journal of Supercritical Fluids. - : Elsevier BV. - 0896-8446. ; 31:3, s. 255-262
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Tidskriftsartikel (refereegranskat)abstract
- The phase behavior of lecithin and water mixtures with addition of the hydrocarbon 1,8-cineole (C10H18O) was investigated using light microscopy and H-2 NMR at atmospheric pressure and with a surplus of supercritical carbon dioxide (15 MPa) between 35 and 80degreesC. The lecithin-water (LW) mixtures consisted of 10 and 20wt.% water in lecithin to which 5, 10, and 20wt.% cineole and supercritical carbon dioxide were added. The addition of cineole to the 10wt.% water in lecithin samples has affected the original lamellar liquid crystalline phase present and mainly transformed it into the reversed hexagonal phase at cineole concentration of 10wt.% and higher. This phase however Only Occurred when 20 wt.% cineole were added to the lecithin samples with 20wt.% water which otherwise was lamellar. The addition of supercritical carbon dioxide to the lecithin/water samples in the absence of cineole resulted in a liquid crystalline lamellar (LC-L-alpha) phase and was the same as in the original phase structure at atmospheric pressure. In the lecithin/water samples with cineole, the addition of supercritical carbon had little effect on the structure. (C) 2004 Elsevier B.V. All rights reserved.
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| 5. |
- da Cruz Francisco, José, et al.
(författare)
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Solubility of three monoterpenes, their mixtures and eucalyptus leaf oils in dense carbon dioxide
- 2002
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Ingår i: Journal of Supercritical Fluids. - 0896-8446. ; 23:1, s. 11-19
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Tidskriftsartikel (refereegranskat)abstract
- The solubility of 1,8-cineole, alpha-pinene, limonene, their mixtures and the extract of eucalyptus leaf oils in supercritical carbon dioxide were determined using the dynamic method at 80, 100, 150, and 250 bar and 40 and 60 degreesC for each pressure. The results showed an increase in the solubility of all oils with an increase in pressure and a decrease with temperature. The mixtures of both pure blends as well as the eucalyptus oil extracts exhibited lower solubility than the pure single oil components in the same conditions. The oil of E. radiata exhibited a better separation of 1,8-cineole at 80 bar and 60 degreesC. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 6. |
- da Cruz Francisco, José, et al.
(författare)
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Supercritical Fluids as Alternative, Safe, Food-Processing Media: An Overview.
- 2003
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Ingår i: Acta Microbiologica Polonica. - 0137-1320. ; 52:Suppl., s. 35-43
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Tidskriftsartikel (refereegranskat)abstract
- The continuous growth of world population and its concentration in the urban areas require food supplies that are continuous, sufficient and of good quality. To resolve this problem techniques have been developed for increasing food quantity and quality. The techniques are applied throughout the food chain from production, conservation and during distribution to the consumers (from "the field to the fork"). During handling of food, chemicals are often deliberately added to achieve improved processing and better quality. This is one of the main reasons food undergoes different kinds of contamination. This overview focuses on the application of supercritical fluids as media for handling food materials during processing with the perspective of reducing chemical contamination of food. Examples of developmental applications of this technique and on research work in process are presented. Emphasis is given to extraction and biotransformation techniques.
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