Preparation of iron-loaded water-in-oil-in-water (W₁/O/W₂) double emulsions: optimization using response surface methodology

Iron deficiency anemia is a major public health problem caused by low iron intake or bioavailability. To overcome the problem of anemia, iron fortification of a variety of food products is being tested worldwide. Ferric sodium EDTA is a desirable iron source for food fortification due to its high bioavailability and ability to prevent binding of iron to phytates during absorption. This study investigated the application of double emulsions for encapsulation and controlled delivery of ferric sodium EDTA stabilized by the lipophilic Span®80 and hydrophilic complex of sodium alginate and sodium caseinate emulsifiers. The influence of factors such as the ratio of internal water to the oil phase, concentrations of alginate or Span®80 and the ratio of water-in-oil emulsion to the external water on internal (d_in) and external emulsion droplet sizes (d_out) was studied by response surface methodology. The feasible range for selection of factors for achieving target values of d_in and d_out was proposed by the response optimizer confirmed by the results of experiments. The results indicate that double emulsion systems may be useful for iron fortification of food products.