Characterization of spray-dried phospholipid particles for the production of beta- carotene-loaded liposomes

Lipid matrices are always an interesting alternative to encapsulate hydrophobic bioactives, as many of them have their absorption enhanced in the presence of lipidic molecules. Among the most studied hydrophobic food ingredient are the carotenoids, known by their prominent antioxidant capacity, and, among them, the beta-carotene is the nutritionally most active one. In this study liposomes (phospholipid vesicles) incorporating beta-carotene were produced by the pro-liposomes technique. Spray-drying was the process chosen to obtain dry phospholipid powders, which were submitted to a subsequent controlled hydration step in order to produce the liposomal dispersions. Purified and non-purified soy lecithins were used as raw materials, as well as crystalline beta-carotene and sucrose (a disaccharide is often used in this type of process to decrease the cristallinity of the atomized powders and facilitate the hydration). X-ray diffraction and scanning electron microscopy were adequate techniques to identify if all the components of the formulations used were completely incorporated in the dry phospholipid powders. Only the formulations fulfilling this requisite were submitted to the hydration, and the addition of non-purified soy lecithin did not seem to change drastically the particle size distribution, but decreased significantly the zeta potential of the liposomal dispersion. The hydration procedure originated liposomes with two populations, with average particle sizes around 300 and 1500 nm and zeta potentials lower than -40 mV.