Optimization of the color masking and coating unit operations for microencapsulating ferrous fumarate for double fortification of salt.

A new coating formulation was developed to eliminate the factor that caused black spots on the iron premix surface, used for making Double Fortified Salt. The formulation is a suspension of titanium dioxide in soy stearin, prepared with ethanol and dichloromethane and applied with a glass sprayer and pan coater. 0-20% / titanium dioxide was suspended in 10% / soy stearin/hydroxypropyl methylcellulose. Coating with a suspension of 15% / TiO in 10% / soy stearin ensured that all the TiO adheres to the premix surface, giving no chance for the recycling of iron contaminated TiO, which caused the black spot. The new coating formulation ensured that over 90% iodine in Double Fortified Salt was retained after 6 months at 45 °C, 60-70% RH. The whiteness of the premix (* = 86.4) matched the Double Fortified Salt whiteness (* = 86.8). Thus, making the new coating method as effective as the previous in desirable characteristics. More so, the new coating method simplifies the existing method by merging the previous color masking, and double coating steps into one step.