An extraction unit (1) has a piercing device (10) for piercing a
capsule (20). The piercing device includes: a base (14) with
peripheral sections, such as generally straight
peripheral sections (14a, 14b, 14c1, 14c2); a plurality of blades (11a, 11b, 11c) that protrude from the base along a longitudinal direction (12a′, 12b′, 12c′), each blade extending laterally generally along one of the
peripheral sections (14a, 14b, 14c1); and a plurality of
assembly members (15a, 15b, 15c), each
assembly member (15a, 15b, 15c) extending and protruding from one of the peripheral sections (14b,14c2). At least one
assembly member (15a, 15c) of said assembly members (15a, 15b, 15c) is located at least in part generally in the longitudinal direction (12b′, 12c′) under a corresponding blade (11b, 11c).