Résumé
A first modeling approach was used to understand the behavior of folate in cowpea seeds during soaking at different temperatures (30 degrees C, 60 degrees C and 95 degrees C). Folic acid, 10-formylfolic acid, 5-methyltetrahydrofolate, and 5-formyltetrahydrofolate were quantified in both the seeds and the soaking water during the process. A 2D-axisymmetric seed soaking simulator was then built considering these 4 folate vitamers to simultaneously describe diffusion, oxidation and interconversion of the single vitamers. The model adjustments revealed the predominance of folate diffusion at 60 degrees C and 95 degrees C (apparent diffusivity 2-3 x 10(-11) m(2) s-(1))whereas at 30 degrees C enzymatic interconversions of all vitamers into 5-methyltetrahydrofolate were observed (reaction rate of 8.0 x 10(-5) s(-1) for 5-formyltetrahydrofolate). The results of this study allow us to recommend a preliminary soaking step to retain folate in seeds and to improve the bioavailability of folates for human nutrition.