Optimal extraction rate coffee capsule with effective seal for diverse group heads

A coffee capsule for coupling in sealing relation with a group head of a coffee-making machine, comprising:

• a cup-like body portion including a side wall;
• a flange whose proximal end meets a bottom end of the side wall,
• the flange comprising a first plateau and a second plateau, the first plateau situated adjacent the bottom end of the side wall such that, at least prior to deformation by a group head, a proximal end of the first plateau meets the bottom end of the side wall at a substantially perpendicular angle, the first plateau raised relative to a top surface of the flange, the flange also comprising a a proximal lip more radially distal than the first plateau and protruding from the top surface of the flange to a point higher than the first plateau,
• the second plateau along the top surface of the flange more radially distal than the proximal lip, the first plateau raised relative to a flat bottom surface of the second plateau,
• a space defined by a wall of the proximal lip, the first plateau and the bottom end of the side wall and that includes the substantially perpendicular angle, is dimensioned for receipt of a first group head such that a bottom surface of the first group head presses the first plateau, a first side of the first group head abuts the bottom end of the side wall and a further side of the first group head abuts the wall of the proximal lip, the area operative to be compressed by the group head and form a fluid-tight sealing engagement with the group head when the coffee capsule mates with the group head,
• the second plateau configured to receive a second group head when the first plateau does not engage the first group head, so as to seal the coffee capsule against the second group head when a bottom surface of the second group head presses against said second plateau, the second plateau dimensioned differently than the first plateau so as to receive the second group head, wherein the second group head is structured differently than the first group head.