2024-03-28T12:41:01Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/1300882020-07-28T06:57:21Zcom_10261_5063com_10261_5col_10261_5066
Effect of fatty acids on self-assembly of soybean lecithin systems
Godoy, César A.
Valiente, Mercedes
Pons Pons, Ramon
Montalvo, Gemma
Fatty acids
Oleic acid
Linoleic acid
Palmitic acid
Small-angle X-ray scattering
Soybean lecithin
With the increasing interest in natural formulations for drug administration and functional foods, it is desirable a good knowledge of the phase behavior of lecithin/fatty acid formulations. Phase structure and properties of ternary lecithin/fatty acids/water systems are studied at 37. °C, making emphasis in regions with relatively low water and fatty acid content. The effect of fatty acid saturation degree on the phase microstructure is studied by comparing a fully saturated (palmitic acid, C16:0), monounsaturated (oleic acid, C18:1), and diunsaturated (linoleic acid, C18:2) fatty acids. Phase determinations are based on a combination of polarized light microscopy and small-angle X-ray scattering measurements. Interestingly, unsaturated (oleic acid and linoleic acid) fatty acid destabilizes the lamellar bilayer. Slight differences are observed between the phase diagrams produced by the unsaturated ones: small lamellar, medium cubic and large hexagonal regions. A narrow isotropic fluid region also appears on the lecithin-fatty acid axis, up to 8. wt% water. In contrast, a marked difference in phase microsctructure was observed between unsaturated and saturated systems in which the cubic and isotropic fluid phases are not formed. These differences are, probably, a consequence of the high Krafft point of the C16 saturated chains that imply rather rigid chains. However, unsaturated fatty acids result in more flexible tails. The frequent presence of, at least, one unsaturated chain in phospholipids makes it very likely a better mixing situation than in the case of more rigid chains. This swelling potential favors the formation of reverse hexagonal, cubic, and micellar phases. Both unsaturated fatty acid systems evolve by aging, with a reduction of the extension of reverse hexagonal phase and migration of the cubic phase to lower fatty acid and water contents. The kinetic stability of the systems seems to be controlled by the unsaturation of fatty acids.
Dr. C.A. Godoy is grateful for her scholarship to the Agencia Española de Cooperación Internacional para el Desarrollo (AECID), Universidad de Alcalá and Banco Santander, through the “Becas Miguel de Cervantes Saavedra” Program, and to the Universidad del Valle for the bibliographic resources provided. Jaume Caelles from the SAXS-WAXS service at IQAC is gratefully for performing the measurements. Imma Carrera is acknowledged for sample preparation. Ignacio Jiménez is grateful for helping in graph improvement.
Peer reviewed
2016-03-15T07:57:35Z
2016-03-15T07:57:35Z
2015-07-01
artículo
http://purl.org/coar/resource_type/c_6501
Colloids and Surfaces - B - Biointerfaces
http://hdl.handle.net/10261/130088
10.1016/j.colsurfb.2015.03.065
en
Postprint
http://www.sciencedirect.com/science/article/pii/S0927776515002556
Sí
open
Elsevier