This method comprises the following steps: flowing drops of a first phase, through a circulation duct, into a second phase that is substantially immiscible with the first phase, each drop comprising a core formed from the first phase and a shell formed from a layer of coacervate inserted between the first phase and the second phase recovering a dispersion containing drops and the second phase in a container injecting a solution for increasing the viscosity of the second phase in the circulation duct or at the outlet of the circulation duct, upstream from the container.