Effect of malting and fermentation on anti-nutritional factors in pearl millet flour

Abstract:

Roughly 83 million tonnes of pearl millet (Pennisetum glaucum) are harvested each year across semi-arid Africa and Asia, yet much of this grain goes underused in processed foods because of its high load of anti-nutritional factors (ANFs). This research examined how malting (germination at 30 °C for 48 h) and natural lactic-acid fermentation (72 h at 37 °C) — applied individually and in sequence — changed the concentrations of phytate, tannins, oxalates, trypsin inhibitors, and polyphenols in pearl millet flour prepared from a local Kano landrace. Raw flour served as the control. Malting alone cut phytate by 38.4% and trypsin inhibitor activity by 41.3%, while fermentation alone reduced them by 44.2% and 48.7%, respectively. The combined treatment delivered the steepest declines across all five ANFs, with phytate dropping 62.7% and trypsin inhibitors falling 67.2%. Tannins and oxalates showed moderate but consistent decreases under every processing route. Protein digestibility improved from 61.3% in raw flour to 79.8% after the combined treatment. These findings offer a low-cost, equipment-light strategy for smallholder processors aiming to raise the nutritional quality of pearl millet products.