The invention relates to an apparatus for delivering powder in a beverage dispenser comprising a hopper for containing a mass of beverage powder. The hopper includes at least one flexible body member and an actuating mechanism coupled with the flexible body member. The actuating mechanism is operatively associated with a mechanical or magnetic driving device which is actuated in an active mode to actuate the actuating mechanism to impart motion to the flexible body member at a frequency that is sufficiently low to correspond to a non-vibrating mode.