A grinder for beans of plant-based products, for example roasted coffee, whose powder is adapted for use in the preparation of beverages, includes a grinding chamber defined by a cylindrical wall, a pair of opposed grinding wheels, at least one of which rotates, and which are located in said grinding chamber, an electric motor for driving the rotating grinding wheel, a first cooling duct extending in said cylindrical wall between a first inlet and a first outlet. A tubular circuit connected to the first cooling duct comprises a motor pump for circulating the fluid, heat dissipater, at least one valve member, an electronic control unit for actuating said motor pump and for turning on said heat dissipater according to the value of temperature sensed by said temperature sensor.
