COMPARATIVE MOISTURE ADSORPTION BEHAVIOUR AND ISOTHERM MODELLING OF SEED POWDERS FROM FOUR BAMBARA GROUNDNUT (VIGNA SUBTERRANEA L. VERDC.) CULTIVARS FROM COTE D IVOIRE

Bambara groundnut (Vigna subterranea L. Verdc.) is a african legume widely cultivated in sub-Saharan Africa and constitutes a nutritionally complete food for many West African populations. Since its seed powder is hygroscopic, mastery of its moisture sorption behavior is essential for optimizing drying and storage conditions and ensuring product quality. Moisture sorption isotherms are fundamental tools for predicting the stability and shelf life of dehydrated food products. The present study therefore sought to characterize and model the hygroscopic behavior of seed powders of four cultivars of bambara groundnut from Cote d Ivoire: Red Mottled Beige (RMB), Uniform Red (UR), Uniform Black (UB) and Beige with Black Hilum (BBH). The experimental adsorption isotherms were determined by the static gravimetric microclimate method at room temperature (29 -1C). Three widely used sorption isotherm models GAB, Oswin and Chung-Pfost were fitted to the experimental data by direct nonlinear least squares regression. The monolayer moisture contents (Mo) of the four powders were estimated from the GAB model parameters. The results showed that the adsorption isotherms of all four bambara groundnut powders are of Type II, according to the BET classification.