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Title
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Adsorption kinetics of some carotenoids at the oil/water interface
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Author
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Abstract
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| The kinetic analysis of the adsorption of two carotenoids (i.e., ethyl ester of beta-apo-8'-carotenoic acid and beta-carotene, all trans-isomers) from n-hexane solutions at the oil/water interface is presented for several carotenoid concentrations in the oil phase. A new kinetic approach is developed and it addresses the diffusion adsorption associated with a reversible interfacial reaction, which describes the reorientation of surfactant molecules between two conformations. This approach leads to a general analytical expression that contains four physical parameters and describes with high accuracy the experimental dynamic interfacial tensions for the two carotenoids, which independently adsorb from n-hexane phase to the n-hexane/water interface. The calculations give the characteristic times for the carotenoid adsorption at the oil/water interface in terms of diffusion relaxation and kinetic relaxation times. The results explain the long time effects on the adsorption of these carotenoids at the oil/water interface. The data are in substantial agreement with the molecular structure of these carotenoids and with the earlier data recorded for cholesterol adsorption at the n-heptane/water interface. Based on these findings, we propose a molecular mechanism for the interfacial transformation of carotenoid molecules at a hydrophobic/hydrophilic interface. (C) 2004 Elsevier B.V. All rights reserved. |
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Language
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English
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Source (journal)
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Colloids and surfaces: B : biointerfaces. - Amsterdam
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Publication
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Amsterdam
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2004
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ISSN
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0927-7765
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DOI
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10.1016/J.COLSURFB.2004.03.019
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Volume/pages
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37
:3-4
(2004)
, p. 83-91
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ISI
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000224020300002
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Full text (Publisher's DOI)
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Full text (publisher's version - intranet only)
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