a cooker designed for sugar products in the form of a tube heat exchanger , in which within a jacket housing a bundle of narrowly spaced pipes flow through by a heat medium extend , which pipes are flowed over by material which are supplied and withdrawn by pipe fittings along the side , wherein deflection plates are provided within the jacket housing which define flow chambers and openings for the transition of the materials to be treated from one flow chamber to the next , thereby characterized , that the deflection plates along a narrow edge area are provided with segment like openings and these openings are situated on diametrically opposing sides of the inner wall of the jacket housing , wherein the opening in the first deflection plate in the flow direction lies opposite the introduction pipe fitting for the material and the opening of the last deflection plate lies opposite the withdrawal pipe fitting .