International audienceMilk protein concentrates (MPCs) must be completely dispersed and dissolved in water to fully present their functional properties. However, MPC powders exhibit low solubility and dispersibility and require long rehydration times. In addition, the powders have limited shelf life as their solubility decreases during storage. It is proposed that improvements in the instant powder drying process will improve the rehydration behaviour of MPC powders. In this paper, the physical and rehydration properties of extrusion-porosified MPC powders were examined and compared with those of conventional spray-dried MPCs. This work clearly confirmed that spray-dried MPC powders showed a low dispersibility index (38%), and after 5 h of rehydration, no sub-micron casein micelles were observed in the dispersed phase. In contrast, extrusion-porosified MPC powders exhibited a very high dispersibility index (96%), and the dispersed phase contained only sub-micron particles after 2 h of rehydration. The results suggest that the improved dispersibility is attributed to the dissociation of casein micelles caused by the extrusion porosification treatment prior to drying. Changes in the microstructure of extrusion-porosified MPC powder particles are proposed to support the significant improvement of the rehydration behaviour