Appliance for preparing a froth from a milk-based liquid which includes a tank for receiving liquid that is to be frothed, and in which liquid a rotatable stirrer is positioned, a stand associated with the tank, and a system for driving the stirrer. The stirrer drive system and the stirrer include magnetic elements allowing the stirrer to be rotationally driven magnetically in the tank. At least one disturbance member is also provided to break or prevent symmetric circulation of the liquid about the median vertical axis of the tank.