title: Impact of surfactant properties on oxidative stability of beta-carotene encapsulated within solid lipid nanoparticles.
abstract: The impact of surfactant type on the physical and chemical stability of solid lipid nanoparticle (SLN) suspensions containing encapsulated beta-carotene was investigated. Oil-in-water emulsions were formed by homogenizing 10% w/w lipid phase (1 mg/g beta-carotene in carrier lipid) and 90% w/w aqueous phase (surfactant + cosurfactant) at pH 7 and 75 degrees C and then cooling to 20 degrees C. The impact of surfactant type was investigated using aqueous phases containing different water-soluble surfactants [2.4% w/w high-melting (HM) lecithin, 2.4% w/w low-melting (LM) lecithin, and 1.4% w/w Tween 60 or 1.4% w/w Tween 80] and a cosurfactant (0.6% taurodeoxycholate). The impact of the physical state of the carrier lipid was investigated by using either a high melting point lipid (tripalmitin) to form solid particles or a low melting point lipid (medium chain triglycerides, MCT) to form liquid droplets. A higher fraction of alpha-crystals was detected in solid particles prepared with high-melting surfactants (HM-lecithin and Tween 60) than with low-melting surfactants (LM-lecithin and Tween 80). With the exception of the HM-lecithin-coated solid particles, the suspensions were stable to particle aggregation during 21 days of storage. beta-Carotene degradation after 21 days of storage was 11, 97, 100, and 91% in the solid particles (tripalmitin) and 16, 21, 95, and 90% in the liquid droplets (MCT) for HM-lecithin, LM-lecithin, Tween 80, and Tween 60, respectively. These results suggest that beta-carotene may be stabilized by (1) LM- or HM-lecithin when liquid carrier lipids are used and (2) HM-lecithin when solid carrier lipids are used. The origin of this latter effect is attributed to the impact of the surfactant tails on the generation of a crystal structure better suited to maintain the chemical stability of the encapsulated bioactive.
authors.affiliation: Department of Food Science and Nutrition, University of Iceland, Hjardarhagi 2-6, Reykjavik 107, Iceland.
authors.forename: Thrandur
authors.initials: T
authors.lastname: Helgason
authors.forename: Tarek S
authors.initials: TS
authors.lastname: Awad
authors.forename: Kristberg
authors.initials: K
authors.lastname: Kristbergsson
authors.forename: Eric Andrew
authors.initials: EA
authors.lastname: Decker
authors.forename: David Julian
authors.initials: DJ
authors.lastname: McClements
authors.forename: Jochen
authors.initials: J
authors.lastname: Weiss
mesh_terms: D004337:Drug Carriers / Q000737:chemistry; D004355:Drug Stability; D054709:Lecithins; D008055:Lipids / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D010084:Oxidation-Reduction; D011136:Polysorbates; D013501:Surface-Active Agents / Q000737:chemistry*; D013997:Time Factors; D019207:beta Carotene / Q000737:chemistry*
chemical_list: D004337:Drug Carriers; D054709:Lecithins; D008055:Lipids; D011136:Polysorbates; D013501:Surface-Active Agents; D019207:beta Carotene