Impact of Surfactant Properties on Oxidative Stability of β-Carotene Encapsulated within Solid Lipid Nanoparticles

• Published in: Journal of agricultural and food chemistry 2009-09, Vol.57 (17), p.8033-8040
• Main Authors: Helgason, Thrandur, Awad, Tarek S, Kristbergsson, Kristberg, Decker, Eric Andrew, McClements, David Julian, Weiss, Jochen
• Format: Article
• Language: English
• Subjects: beta Carotene - chemistry; beta-carotene; Biological and medical sciences; chemical degradation; coatings; crystal structure; droplets; Drug Carriers - chemistry; Drug Stability; emulsions; Food Chemistry/Biochemistry; Food industries; Fundamental and applied biological sciences. Psychology; Lecithins; lipids; Lipids - chemistry; medium chain fatty acids; melting point; microencapsulation; Nanoparticles - chemistry; nanotechnology; oil-water interface; Oxidation-Reduction; oxidative stability; particles; phosphatidylcholines; physicochemical properties; polysorbate; Polysorbates; storage quality; Surface-Active Agents - chemistry; surfactants; taurodeoxycholate; Time Factors; tripalmitin
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf901682m

The impact of surfactant type on the physical and chemical stability of solid lipid nanoparticle (SLN) suspensions containing encapsulated β-carotene was investigated. Oil-in-water emulsions were formed by homogenizing 10% w/w lipid phase (1 mg/g β-carotene in carrier lipid) and 90% w/w aqueous phase (surfactant + cosurfactant) at pH 7 and 75 °C and then cooling to 20 °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 α-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. β-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 β-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.