Résumé
In Africa, micronutrients and notably essential mineral deficiencies are particularly important to fight 1 . Beside supplementation, one of the means is to reduce phytic acid (PA), an antinutritional factor able to chelate divalent minerals, such as iron and zinc. PA is present in consumed pulse seeds and their corresponding food products 2 . If in cereal grains, PA may be removed with the outer layers along milling or debranning, in pulse seeds it remains in the products due to its location in the cotyledons 3 . Part of the strategy could be to enhance endogeneous phytase activities which hydrolyze PA in lower phosphorylated inositol phosphates unable to complex minerals 4 . Choosing two type of seeds belonging to the main consumed pulse family of Fabaceae and the same Vigna genus, i.e. bambara groundnut (Vigna subterranea) and cowpea (Vigna unguiculata), we demonstrated the efficiency of hydro-thermal treatment to reduce PA and undertook a modeling study to describe the involved mechanisms. This model allowed to determine part of initial PA content released by diffusion after seed soaking at elevated temperature or due to phytase hydrolysis or remaining in seeds. Comparison between results obtained using either bambara or cowpea seeds sharing similar structure but different size and hardness and further processing of bambara groundnuts to remove outer layers or transform it into flour allowed to pinpoint the involvement of the seed structure in these mechanisms. We demonstrated that the molar ratio between phytic acid and iron or zinc decreased more significantly from dehulled soaked seeds, a prerequisite to increase mineral bioavailability 5 .