Effect of stirring speed and particle size on couscous powder reconstitution

Couscous powders require to be reconstituted with water or steam to be used. Wetting, swelling, and dispersion occur during couscous powder reconstitution with water. Fine couscous was the least wettable, with a clearly apparent swelling step and depended on the stirring speed: increased stirring led to a decrease in swelling time and a lower maximal particle diameter reached during the swelling step. Dispersion lasted longer than the wetting step and it was shortened at higher stirring speed. For the medium couscous, the swelling step was not observed due to its high wettability. Dispersion was its limiting reconstitution mechanism and was faster for medium couscous whatever the stirring speed. Based on SEM analysis, this could be explained by the more dispersible structure of the medium couscous, as it is composed of more agglomerates. Although the reconstitution kinetics of medium and fine couscous powders differed, the final particle size distributions were similar.