A device and a method for heating and foaming a liquid, in particular a beverage such as a milk-containing beverage for example. The device comprises a steam generator, a pressurized gas source, and a pump means which is connected to the steam generator and the pressurized gas source for transporting a steam/gas mixture into the liquid. The pressurized gas source comprises a controllable switching valve in order to generate pressure pulses. The pressure pulses generated by the pressurized gas source are introduced into the pump means and mixed with the liquid in the pump means, whereby the liquid is foamed. The foam properties of the foamed liquid, such as consistency, creaminess, density, and porosity, can be influenced by the frequency, amplitude, and pulse duration of the pressure pulses.