Formation, characterization, and stability of encapsulated hibiscus extract in multilayered liposomes

Transparent liposomes (1, 2 and 5% w/w soy lecithin) containing anthocyanin-rich hibiscus extract (Hibiscus sabdariffa) (0.2, 0.4 and 0.8% w/v) were prepared by high pressure homogenization (micro-fluidization) at 22,500 psi in acetate buffer (0.25 mol/L, pH 3.5). Liposomes containing extract had mean particle diameters of less than 46 nm, similar to control liposomes (32-46 nm). The encapsulated amount of hibiscus extract in liposomes was analyzed between 63 and 72% w/v. Transparent liposomes containing hibiscus extract were oxidatively stable over a period of 145 days, i.e. significantly less hexanal (<90 mu mol/L) was generated in comparison to liposomes containing no extract (>1100 mu mol/L). A layer-by-layer electrostatic deposition method was used to prepare multilayered liposomes with interfacial membranes consisting of chitosan and pectin. z-Average particle diameter of control liposomes increased to 65 nm after chitosan coating. After deposition of the second layer pectin, the z-average particle diameter increased to approximately 200 nm. The zeta-potentials of the different liposomes changed from -26 mV to 70 mV for the chitosan coating and to approximately -20 mV for the second pectin coating. The highest lecithin concentration of liposomes containing hibiscus extract coated with pectin formed aggregation and was physically unstable. All coated liposomes containing hibiscus extract had higher particle diameters compared to control liposomes. These multilayered liposomes were physically stable for about 30 days. Our results, thus, demonstrate that multilayered polymer coatings of liposomes are highly competent carrier systems for anthocyanins. Moreover, the incorporation of hibiscus extract reduced the fat oxidation in liposomal systems. (C) 2013 Elsevier Ltd. All rights reserved.