Abstract: The disclosure relates to an apparatus for controlling the holding time in a holding tube in infusion heating. The infuser is of the type which consists of a pressure vessel (1) with a conical bottom region (2). The pressure vessel (1) has an inlet (3) for product in its upper region and an outlet (8) with an outlet valve (9) in the lower region. The pressure vessel (1) also has an inlet (5) for steam. In the conical bottom region (2) of the pressure vessel (1) there is disposed a conical body (6) which, to the greater part, fills the conical bottom region (2). The remaining space (7) between the bottom region (2) and the conical body (6) constitutes a holding tube. The outlet of the pressure vessel (1) is in communication with a vertical tube (11). In the vertical tube (11) there is disposed a level indicator (14) which controls the level in the holding tube in that the level indicator (14) controls the outlet valve (9).