LAUSR

BACKGROUND Norbixin, a carotenoid extracted from annatto seeds, is widely utilized as a natural pigment in foods, cosmetics, and medicines. Its water-solubility is relatively high under neutral or alkaline conditions but low under acidic conditions, which limits its application in some food products. RESULTS This problem was overcome by utilizing liposomes to encapsulate the carotenoids so that they could be easily dispersed within acidic solutions. The norbixin was loaded into the liposomes using the pH-driven method. Liposomes were produced by passing aqueous phospholipids dispersions through a microfluidizer under high pressure. Norbixin was then added to the liposomes dispersions at pH 7.0 and then driven into the hydrophobic domains of the phospholipid bilayers by acidifying the system. Measurements of the encapsulation efficiency showed that the norbixin was successfully loaded into the liposomes using the pH-driven method. X-ray diffraction analysis showed that the norbixin was in an amorphous state after being incorporated into the liposomes. Encapsulation of norbixin within the liposomes was also shown to increase its water-dispersibility and chemical stability under acidic pH conditions. CONCLUSION The pH-driven method therefore provides a useful means of increasing the application of this bioactive carotenoid within functional foods and other products. This article is protected by copyright. All rights reserved.