Abstract: For aftertreatment of clarified juices, the juice is brought into contact with an agent, e.g., PVPP, and is filtered in a crossflow filtration device (11) and the aftertreated juice is separated as permeate from the agent. The agent can be regenerated by the addition of water and lye either inside or outside the unit. After regeneration, the lye is again flushed out by diafiltration on the permeate side of crossflow filtration device (11). With the aid of crossflow filtration, the economic efficiency and the universal applicability with respect to the use of agents of the unit can be considerably increased and the treatment quality of the juice can be improved.