A method for the preparation of a liquid product such as coffee by means of hot liquid and/or steam introduced into a cartridge (10) containing a dose of ground coffee envisages introducing the hot liquid and/or steam into the cartridge (10) thus bringing about deformation of at least one portion (1420) of a bottom (142) of the cartridge (10) and consequent perforation of the aforesaid bottom (142) by an array of perforating tips (10). The cartridge (10) is set with the bottom (142) facing the array of perforating tips (10) but at a distance therefrom so that the bottom (142), by undergoing deformation, comes into contact with the array of perforating tips (10) with a delay with respect to the start of the action of introduction of the aforesaid hot liquid and/or steam into the cartridge (10).
