A beverage preparation machine comprising a beverage ingredient powder storing container and a mixing chamber. The mixing chamber being movable between a dosing position, where the outlet of the storing container emerges in the mixing chamber inlet, and a mixing position, where the outlet of the storing container does not emerge in the mixing chamber inlet. The dosing position being placed at a lower vertical position than the mixing position, and wherein the machine comprises an auger at the bottom of the beverage ingredient powder storing container configured for guiding a dose of powder to the outlet of the storing container. The machine also comprises a door at the outlet of the storing container, the door being configured so that when the mixing chamber moves to the dosing position the movement of the mixing chamber activates the opening of the door and when the mixing chamber moves to the mixing position the movement of the mixing chamber induces the closure of the door.