Double fortified (iron and zinc) spray-dried microencapsulated premix for food fortification

This study examines spray-drying microencapsulation of iron and zinc simultaneously as a strategy to combat iron and zinc nutrient deficiency, and in order to ascertain the possibility of delivering these nutrients together. Iron and zinc bioaccessibility and release kinetics were assessed through simulated digestion gastro-intestinal (pH 2.0 and pH 6.6) on three optimized microencapsulated formulations containing ferrous and zinc sulphate using whey protein isolate (WPI) and Eudraguard as coating materials. Optimized formulations depicted up to 97 % encapsulation efficiency for iron and 52 % encapsulation efficiency of zinc, with up to 73 % yield from the spray-drying process. In stomach conditions, the microcapsules released close to 100 % of the iron and zinc within 30 min at pH 2.0, and within 45 min of intestinal digestion at pH 6.6. Thus, the microcapsules showed higher resistance to intestinal conditions. The Higuchi mathematical model was found to best fit the experimental data for iron and zinc release, suggesting a transport phenomenon governed by the diffusion process through the coating material. The results from this study shall guide technology development using proteins that could resist gastro-intestinal conditions as well as understanding the complex release process into the release mechanisms.