Germination improves iron and zinc bioaccessibility in micronutrient powder-fortified maize, millet, and sorghum porridges

Iron and zinc deficiencies among young children in low- and middle-income countries are exacerbated by poor mineral bioaccessibility from cereal-based complementary foods rich in antinutritional factors. Because germination is a simple, low-cost household processing method that activates endogenous phytase enzymes to degrade phytate, it was investigated as a strategy to improve iron and zinc bioaccessibility in micronutrient powder (MNP)-fortified cereal porridges. To evaluate the effect of germination on iron and zinc bioaccessibility in MNP-fortified maize, millet, and sorghum porridges used for complementary feeding. Locally sourced maize, finger millet, and sorghum grains were either germinated (48 h, 28–35 °C) or left non-germinated before milling. Porridges were prepared using standardized community-based methods and fortified after cooking with MNP. Phytate, tannin, total phenolic, and mineral contents were determined, while iron and zinc bioaccessibility were assessed using an in vitro dialysability model. Data were analysed using two-way ANOVA with Bonferroni-adjusted post hoc tests. Germination significantly reduced phytate by 48.8–55.2% in all porridges (p < 0.05). In sorghum, tannin and total phenolic contents decreased by 61.6% and 72.0%, respectively (p < 0.001). Iron bioaccessibility increased significantly in maize (1.3–2.7%) and finger millet (1.8–5.5%), while zinc bioaccessibility increased in maize (12.6–30.7%), finger millet (10.6–33.7%), and sorghum (15.5–38.8%) (all p < 0.05). Contributions to recommended dietary allowances remained modest. Germination reduced antinutritional factors and improved iron and zinc bioaccessibility in MNP-fortified cereal porridges. Finger millet and sorghum showed the greatest potential for improving complementary food quality in resource-limited settings. What is already known? Cereal-based complementary foods commonly consumed in Low- and Middle-Income Countries (LMICs) are often high in phytate and polyphenols that reduce iron and zinc bioaccessibility, even when foods are fortified with micronutrient powders. What this study adds? Demonstrates that germination substantially reduces phytate and selected phenolic compounds in maize, millet, and sorghum porridges, thereby improving the in vitro bioaccessibility (dialyzable fraction) of iron and zinc in micronutrient powder-fortified porridges. How might this study affect practice/policy? Supports the incorporation of germination into household and community complementary feeding programs to enhance the effectiveness of micronutrient powder fortification and improve the nutritional quality of cereal-based diets in resource-limited settings.