Method for producing a coffee beverage in a coffee machine

A method for producing a coffee beverage in a coffee machine (10),

• wherein the coffee machine (10) comprises:
• a brewing device (30) with a brewing chamber (35) for receiving coffee powder, said brewing chamber (35) comprising at least one fluid inlet (36) and one fluid outlet (45);
• a fluid system (12) with a fluid feed line (26) connected to the fluid inlet (36) and a fluid conveyor (15) for conveying a heated fluid through the fluid feed line (26) and with a drainage outlet (65) separate from the fluid outlet (45),
• said drainage outlet (65) being in, or being configured to be brought into fluidic connection with the brewing chamber (35) and/or the fluid feed line (26) so that a residual fluid is enabled to be discharged from the fluid feed line (26) and/or the brewing chamber (35) through the drainage outlet (65);
• wherein the brewing device (30) comprises:
• a brewing cylinder (31) with an internal space (32) which has a longitudinal axis (LA) and is limited on one end face by an end surface (40) extending transversely to the longitudinal axis (LA) and is limited radially to the longitudinal axis (LA) by a side wall (41) extending about the longitudinal axis (LA);
• a brewing piston (34) which extends in the direction of the longitudinal axis (LA) so that an end surface (34a) of the brewing piston (34) is arranged opposite the end surface (40) of the internal space (32),
• wherein the brewing chamber (35) extends between the end surface (40) of the internal space (32), the end surface (34a) of the brewing piston (34) and the side wall (41) and the brewing piston (34) is configured to be moved along the longitudinal axis (LA) so that a distance (D1, D2) between the end surface (40) of the internal space (32) and the brewing piston (34) is changeable;
• wherein the method comprises the following steps (a)-(d):
• (a) introducing a predetermined quantity of coffee powder (38) into the brewing chamber (35),
• (b) conveying heated fluid through the fluid feed line (26) into the brewing chamber (35) for preparing a coffee beverage through brewing the coffee powder in the brewing chamber (35) and dispensing a prepared coffee beverage from the brewing chamber (35) through the fluid outlet (45),
• (c) conveying a first quantity of heated fluid through the fluid feed line (26) into the brewing chamber, whereby step (c) is carried out before step (a),
• (d) discharging at least one part of the first quantity of heated fluid supplied in step (c) from the brewing chamber (35) before the start of step (a),
• wherein in step (d), the at least one part of the first quantity of heated fluid supplied in step (c) is discharged through the drainage outlet (65),
• wherein the method comprises the following steps (f) and (g):
• (f) before the start of or during step (c), the brewing piston (34) is arranged in such a way that the brewing piston (34) is at a first predetermined distance (D2) relative to the end surface (40) of the internal space (32);
• (g) during step (d), the brewing piston (34) is moved along the longitudinal axis (LA) so that the brewing piston (34) is relative to the end surface (40) of the internal space (32) at a distance (D1) which is smaller than the first predetermined distance (D2).