| 1. |
- 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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| 2. |
- 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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| 3. |
- Francisco, J D, et al.
(författare)
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Liquid crystalline properties and extractability of monoolein-water systems by supercritical carbon dioxide
- 2003
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Ingår i: Colloids and Surfaces A: Physicochemical and Engineering Aspects. - 0927-7757. ; 213:1, s. 69-78
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Tidskriftsartikel (refereegranskat)abstract
- The influence of phase structure on the extraction recovery of monoolein from monoolein-water systems by supercritical carbon dioxide was investigated. Two monoolein-water mi tures at concentrations of 9 wt% water and 18 wt% water, respectively, were studied. H-2-NMR was used to monitor changes of the phase structures in supercritical conditions. The results showed that the phase structure and the water-monoolein interactions play a role on the extraction yield. The monoolein recovery was higher in the 9 wt% water sample in which L-alpha phase was present compared to the 18 wt% water sample in which the L-alpha melted to yield a L-2 phase. When the phase structures were the same in both samples, the extraction recovery was determined by the solubility properties of the components of the system. The changes due to the presence of supercritical carbon dioxide were shown also to depend on the water concentration of the monoolein-water mixture besides the temperature. The 18 wt% mixture showed a L-2 phase structure in all the range of the temperature investigated while the 9 wt% water mixture showed phase changes from L-alpha phase to L-2 phase in the same temperature range. (C) 200 Elsevier Science B.V. All rights reserved.
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| 4. |
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| 5. |
- 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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| 6. |
- 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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| 7. |
- Dauksas, E, et al.
(författare)
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Comparison of oil from Nigella damascena seed recovered by pressing, conventional solvent extraction and carbon dioxide extraction
- 2002
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Ingår i: Journal of Food Science. - : Wiley. - 0022-1147 .- 1750-3841. ; 67:3, s. 1021-1024
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Tidskriftsartikel (refereegranskat)abstract
- Nigella damascena seeds were extracted by cold press, in a Soxhlet apparatus and with CO2 The yield obtained with liquid CO2 was only 10.57%. EtOH (1%) increased the yield by 50%. CO2-extracts were separated into the 2 fractions. The yield in the first fraction increased 2 times by increasing the pressure from 150 to 350 bar. EtOH (1%) increased the yield 2 times at 150 bar. Linoleic acid was the major fatty acid (43.71 to 50.83%), followed by oleic (14.87 to 23.65%), stearic (15.07 to 23.24%), and palmitic (10.13 to 12.07%) acids. Elemenes (21.38% to 29.16%) were the most abundant volatile constituents, free fatty acids constituted from 35.04% to 51.18%, the majority being linoleic (32.83 to 40.58) (Range for linoleic should be 24.51 to 40.58%-see Table 3) and oleic acids (4.96 to 13.32).
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| 8. |
- Dauksas, E, et al.
(författare)
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Effect of fast CO2 pressure changes on the yield of lovage (Levisticum officinale Koch.) and celery (Apium graveolens L.) extracts
- 2002
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Ingår i: Journal of Supercritical Fluids. - 0896-8446. ; 22:3, s. 201-210
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Tidskriftsartikel (refereegranskat)abstract
- The effect of pressure alterations on the yield of CO2, extracts from different anatomical parts of lovage (Levisticum officinale Koch.) and celery (Apium graveolens L.) was studied. It was found that by applying frequent pressure changes in the extraction vessel it is possible to increase the rate of the isolation of CO2 soluble materials from lovage seeds and leaves, lovage and celery roots. However, after passing a sufficient amount of the supercritical solvent, the yields were similar both for constant and pulsing extraction pressures. The composition of the extracts was analyzed by gas chromatography and mass spectrometry and it was found that the phthalides were very important constituents in the extracts from all the anatomical parts of lovage, while linoleic acid was the most abundant component in the celery root extracts. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 9. |
- Dauksas, E, et al.
(författare)
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Supercritical fluid extraction of borage (Borago officinalis L.) seeds with pure CO2 and its mixture with caprylic acid methyl ester
- 2002
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Ingår i: Journal of Supercritical Fluids. - 0896-8446. ; 22:3, s. 211-219
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Tidskriftsartikel (refereegranskat)abstract
- The influence of different pressures of CO2 and the addition of caprylic acid methyl ester as an entrainer was studied for the extraction process of borage seed. The increase of CO2 pressure from 100 to 350 bar resulted in the increase in extract yield from 0.14 to 24.29% (w/w) while the changes in the extract composition were not so considerable. The highest solubility of pure caprylic acid methyl ester in dense CO2 was determined at 100 and 300 bar (approximately 1 g of ester in 1 g of CO2). The addition of this entrainer increased the yield of pure extract up to 47.8 times at 100 bar, 2.4 times at 200 and 300 bar. Due to the high solubility of caprylic acid methyl ester at the lower (100 bar) pressure it is easy to separate the entrainer, which constituted only 4.22% of the total borage seed extract. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 10. |
- Gekas, Vassilis, et al.
(författare)
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Contact angles of ultrafiltration membranes and their possible correlation to membrane performance
- 1992
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Ingår i: Journal of Membrane Science. - 0376-7388. ; 72:3, s. 293-302
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Tidskriftsartikel (refereegranskat)abstract
- The captive bubble method was used to describe the wetting characteristics of a number of commercial ultrafiltration (UF) membranes. The membranes belonged to one of two homologous (same material, different cut-off) series made by the same manufacturer. One series was made of polysulphone and the other one of cellulose triacetate. The porosimetric characteristics of the membranes have also been measured. The combined data were used to explain the fouling behaviour of the membranes upon ultrafiltration of solutions containing dextran, whey protein concentrate and silicate sols. The cellulose triacetate series is characterized by lower receding contact angle and smaller contact angle hysteresis and shows better flux behaviour (permeate flux during UF and pure water flux recovery at the end of UF) than the polysulphone series. Within the same series the mean permeability pore size shows a better correlation with membrane flux behaviour than with contact angle hysteresis.
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