Apparatus for preparing a beverage using a soluble preparation, comprising a container for the soluble preparation, a mixer provided with a mixing chamber, said chamber having a filling inlet for the soluble preparation, at least one opening for supplying a liquid for solubilizing the preparation and forming the beverage, a duct for evacuating any vapour and/or aerosol which forms during preparation of the beverage, said duct comprising a suction fan, as well as an opening for dispensing the prepared beverage, a centrifuging device housed inside said mixing chamber and rotationally operated by an associated electric motor positioned outside said chamber, means for conveying a predetermined quantity of soluble preparation from the said container to the filling mouth of said mixing chamber, as well as means for conveying the solubilization liquid from the associated source to the respective opening of the mixing chamber.The apparatus also includes a movable member for closing and opening the said filling inlet of the mixing chamber and means for displacing this member from a position where it keeps the filling inlet open during introduction of a quantity of soluble preparation and a position where it is over said inlet and keeps it closed during formation of the beverage and vice versa.