Impact of Fermentation Variables on the Bioavailability of Iron and Zinc in Sorghum-Based Foods for Northern Nigeria

Iron and zinc deficiency are prevalent among populations in northern Nigeria who depend heavily on sorghum-based diets, where the high phytate content of sorghum inhibits mineral bioavailability. Fermentation is widely applied in traditional sorghum processing and has been reported to reduce phytate content, potentially improving mineral bioavailability. This study empirically investigates the impact of fermentation variables including duration, temperature, starter culture type, and malting pre-treatment on the bioaccessibility of iron and zinc in sorghum porridge and tuwo produced in Kano State, North West Nigeria. Fermentation experiments were conducted using a controlled factorial design. Phytate, iron, and zinc were determined by standard analytical methods. In vitro iron and zinc bioaccessibility were assessed using the pepsin-pancreatin dialysability method. Antinutritional factors including tannins and trypsin inhibitors were also quantified. Results showed that combined malting and lactic acid fermentation for 24 hours at 37 degrees Celsius reduced phytate by 87 percent and increased in vitro iron bioaccessibility from 4.2 to 18.7 percent and zinc from 8.1 to 29.4 percent. Starter culture supplementation with Lactobacillus fermentum further improved phytate reduction compared to spontaneous fermentation. The study draws on recent iron and zinc bioavailability literature for cereal-based diets in sub-Saharan Africa. Findings provide evidence for interventions in traditional sorghum processing to improve nutritional quality, with implications for nutrition policy and community food processing programmes. Keywords: iron bioavailability, zinc, sorghum, fermentation, phytate