Effect of Fermentation and Germination on the Iron and Zinc Bioavailability of Cowpea-Based Complementary Foods in Plateau State, North Central Nigeria

Iron and zinc deficiency among children under five years in Nigeria remains a persistent challenge with important consequences for cognitive development and immune function. Cowpea is an iron and zinc-rich legume widely cultivated in North Central Nigeria, yet high phytate content significantly limits mineral bioavailability. This study evaluated the effect of fermentation and germination processing treatments on iron and zinc bioavailability in cowpea-based complementary food formulations developed for children aged 6 to 24 months in Plateau State. Cowpea seeds sourced from Vom were subjected to controlled fermentation (48 and 72 hours) and germination (24 and 48 hours) before incorporation into complementary food blends with maize and baobab powder. Iron and zinc bioavailability was estimated using the in vitro pepsin-pancreatin digestion method with dialysability as a bioavailability proxy. Phytate and tannin content were also determined. Results showed that 72-hour fermentation reduced phytate content by 72 percent and improved estimated iron dialysability from 9.4 to 22.6 percent, while 48-hour germination increased zinc dialysability from 11.2 to 24.8 percent. Combining fermentation and germination in sequential processing achieved the greatest reduction in anti-nutritional factors and the highest mineral dialysability values. Energy density of all formulations exceeded 100 kcal per 100ml at appropriate viscosity. The study provides evidence supporting dual processing as a low-cost strategy to improve micronutrient bioavailability in cowpea-based complementary foods in North Central Nigeria. Keywords: cowpea, bioavailability, fermentation, germination, complementary food.