A capsule for the preparation of a nutritional product in a device adapted to supply liquid into the capsule. The capsule includes at least one compartment containing nutritional ingredients for the preparation of the nutritional product in combination with the supplied liquid, and a filter adapted for removing contaminants contained in the liquid. The capsule also has a selectively openable gas inlet which is placed on or in the capsule to allow gas introduction from outside the capsule into the compartment without passing through the filter.
