Controlling and/or treating heat-sensitive liquid food products ensures improved control of a filling level in an infuser container. Therefore, a constant dwell time of the product to be heated is reached in the event of product-fouling in the centrifugal pump. The pump is designed such that one part of a volume flow of the product, transported by an impeller wheel, regularly rinses the impeller wheel and the areas of a pump chamber that are directly adjacent to the impeller wheel. A reduction in the volume flow of the centrifugal pump is then counteracted by increasing the initial rotational speed if the reduction is simultaneously associated with a drop in temperature of the product. The increase of the initial rotational speed is carried according to the drop in temperature of the product and/or an increase in the temperature of the steam to constantly maintain at least the temperature of the product.