Optimization of Unit Operations for Microencapsulating Ferrous Fumarate During Scale-Up of Double Fortification of Salt with Iron and Iodine

Objectives: This study evaluates factors responsible for the floating of iron premix in double fortified salt (DFS), which initially affected the large-scale implementation of the salt fortification program in India, and provides solutions to the scale-up of the technology. Materials and Methods: To mitigate this time-sensitive scale-up challenge. First, the iron premix samples were obtained from the industrial scale-up pilot studies in India, evaluated for the impact of the amount of coating material (5 per cent, 7.5 per cent, and 10 per cent (in weight)), type of formulation (soy stearin, SEPIFILM and hydroxypropyl methylcellulose), amount of titanium dioxide (25-35 per cent (in weight)) used for color masking; Second, we studied the effect of change in the composition of the coating, from 10 per cent (in weight) soy stearin to a double coat with 5 per cent (in weight) hydroxypropyl methylcellulose and 5 per cent soy stearin or 10 per cent soy stearin and 1 per cent (in weight) lecithin mixture, on particle density, floating or sinking property of the iron premix, and on the stability of iodine in the DFS. Results: It was observed that the hydrophobic nature and the amount of soy stearin used for coating caused the floating issue. The double coating with 5 per cent hydroxypropyl methylcellulose and 5 per cent soy stearin was preferred because lecithin in soy stearin enhanced the moisture-aided adverse interaction between iron and iodine. Shelf-life storage studies proved over 80 per cent iodine retention after 12 months of storage in the DFS formulated with iron premix double-coated with hydroxypropyl methylcellulose and soy stearin. Conclusion: This proffered solution enabled the full implementation of the double fortification program in India