A method for treating a liquid food product, wherein said liquid food product is guided through a device for applying a pulsed high voltage electric field treatment to a fluid flow, said device comprising a chamber comprising an inlet with an inlet cross sectional area, an outlet, a ring-shaped treatment zone arranged between the inlet and the outlet, a widening part between said inlet and said treatment zone, a flow body in said chamber providing in said chamber the ring-shaped treatment zone, and at least a first electrode and a second electrode positioned for providing an axial electric field in said treatment zone, wherein the ring-shaped treatment zone is defined by the inner surface of the chamber and the outer surface of the flow body, wherein said flow body at its upstream end is provided with a tip, wherein said chamber has a ring-shaped region upstream of, and connecting to, said treatment zone, wherein said upstream ring-shaped region has an axial length of at least five times a treatment zone height, wherein said upstream ring-shaped region has a cross sectional area (A3 minus A4) between 0.9 and 2.0 times the cross sectional area of said treatment zone, and wherein said treatment zone is circle-ring shaped, wherein said chamber comprises said widening part between said inlet and said upstream ring-shaped region, wherein said widening part gradually widens in cross sectional area from said inlet in a downstream direction, wherein said cross sectional area of said inlet in a downstream direction gradually flares out until the cross sectional area is at least 5 times larger with respect to said inlet cross sectional area, and wherein further downstream said chamber comprises said flow body configured to continue said cross section into a ring-shape with a smooth and gradual reduction of the cross sectional area in further downstream direction with at least 1.5 times and up to the ring-shaped treatment zone, wherein said chamber has further a downstream ring-shaped region downstream of, and connecting to, said treatment zone, wherein said downstream ring-shaped region has an axial length of at least two times the treatment zone height, wherein the length of the treatment zone is between 2 and 5 times the height of the treatment zone, wherein the cross sectional area of said treatment zone is at least 1.5 times the cross sectional area of said inlet, wherein said downstream ring-shaped region has a cross sectional area between 0.9 and 2.0 times the cross sectional area of said treatment zone, wherein said cross sectional area of said ring-shaped region upstream of said treatment zone is substantially constant over an axial length of at least 5 times the height of the treatment zone, and wherein said cross sectional area of said downstream ring-shaped region downstream of treatment zone is substantially constant over an axial length of at least 2 times the height of the treatment zone, wherein said first electrode is positioned upstream of said treatment zone and said second electrode is positioned downstream of said treatment zone for providing said axial, pulsed electric field with field lines substantially parallel to a flow direction of fluid in said treatment zone when said device is in operation, the method further comprising providing the liquid food product in a laminar flow in the ring-shaped treatment zone, and applying a pulsed electric field between said first electrode and second electrode, wherein a potential difference is applied to said electrodes to result in an electrical field of 20-60 kV/cm in said treatment zone, and wherein a potential difference is applied to said electrodes with a pulse frequency of less than 100 Hz, and with a pulse width of 1-5 microseconds.