PRODUCTION AND STABILITY OF LIPOSOMES CONTAINING FERROUS SULPHATE

Iron is a prevalent mineral in terms of nutritional deficiency around the world, which inadequate intake is associated with iron-deficiency anemia. An alternative to reduce cases of anemia is food fortification. It has adopted the addition of free forms of iron, although in this form the ion is less stable and can also affect the stability of the food matrix. To improve the iron absorption, it has been added ascorbic acid that reduces the ferric iron (III) to ferrous state (II). The encapsulation is a trend technology to promote stability and delivery of nutrients which are sensitive to environmental and process parameters. In this way, the liposomal vesicles highlight as a potential delivery system. Thus, this study aimed to produce liposomes containing ferrous sulfate and ascorbic acid and evaluate their stability during storage time at refrigeration temperature. The liposomes were produced by the Reverse-Phase Evaporation method and characterized via Transmission Electron Microscopy. The particle size distribution was evaluated by Dynamic Light Scattering in terms of the average diameter and the polydispersity index. The pH and ζ-potential of the liposomal dispersion were also monitored. The relative iron II stability as function of storage time was monitored spectrophotometrically using the phenanthroline method. The oxidative stability was analyzed as a function of storage time by the quantification of 2-thiobarbituric acid reactive substances. According to electron micrographs, large liposomes and multivesicular structures were produced. Besides, it was possible to confirm the encapsulation of ferrous sulfate in the micrograph darkness area. The liposomal dispersion did not change significantly (p<0.05), during 42 days of storage, in terms of average diameter and polydispersity, reaching values around 300 nm and 30%, respectively. On the other hand, during 42 days the ζ-potential values varied by about 50% (p<0.05), with an increase of negative charges, and the pH values varied by 2.0% (p<0.05). This variation can be linked to the possible rupture of some vesicles, releasing encapsulated material in the environment. The ζ-potential increase helps the dispersion stability, as less interaction exists between the colloidal particles, preventing aggregation. Even if the pH values had shown variation, they remained in the range of the liposome stability range (neutral pH). Lipid oxidation increased by about 48% (p<0.05) (day 0 - day 42) which can be linked to the release of lipids in the environment with the disruption of liposomal vesicles. The relative iron II content was approximately 35% (p<0.05) after 48 days. The decline of iron II concentrations may be related to its oxidation even with the presence of ascorbic acid. Although the encapsulation of iron salts in liposomes is not much explored, the results showed that technique is a promising alternative for fortification of aqueous-based food matrices, such as whole milk.