Abstract: The invention relates to a sealed cartridge, provided to be extracted under pressure, containing a substance (15) for preparing a beverage, comprising a dish (9) with a bottom (10) and a side wall (11), having substantially the shape of a frustum of a cone, and a circular edge with a diameter greater than the bottom, and a cover (12) welded to the periphery of the edge of the dish, in which the cover (12) consists of a flexible material which is impermeable to oxygen, chosen from the group consisting of aluminum, an aluminum/plastic composite, an aluminum/plastic/paper composite, pure or multi-layer plastic, the said cartridge not comprising a filter or a weakening zone and the cover being intended to be torn only through the effect of the force of the extraction fluid when extraction starts, the said cartridge comprising, in the dish at the level of the bottom, a barrier (13) that is automatically resealable against leakage of the substance upon withdrawal of the fluid injection needle.