Treatment apparatus and method for preserving pumpable food products in a pulsed electric field

Abstract

An apparatus for preserving food products in a pulsed electric field comprises a treatment chamber having an inlet for food products to be treated and an outlet fortreated food products and has an effective area of flow having rounded corners. The treatment chamber further comprises at least one first electrode and at least one second electrode which are disposed in such a way that the field lines of the electric field run parallel to one another, as well as an energy source and a potential controller to control the potential on at least one first electrode and on at least one second electrode in order to generate a pulsed electric field, of such design that the electric field in the effective area of flow is constant. In a method for preserving food products in a pulsed electric field, the direction of said pulsed electric field in successive pulses is rotated through 90°.

What is claimed is:  
     
         1 . Treatment apparatus for preserving pumpable food products in a pulsed electric field, said apparatus comprising a treatment chamber with an inlet for food products to be treated and an outlet for treated food products, the treatment chamber being provided with a system of electrodes which comprises at least one first electrode and at least one second electrode, as well as an electrical energy source connected to the electrodes and a potential controller to control the potential on at least one first electrode and on at least one second electrode in order to generate a pulsed electric field, wherein the treatment chamber has an effective area of flow having rounded corners and the at least one first electrode and the at least one second electrode of the system of electrodes are disposed in such a way that the field lines of the electric field run parallel to one another and the potential controller is of such design that the electric field in the effective area of flow is uniform.  
     
     
         2 . Treatment apparatus according to  claim 1 , wherein the treatment chamber comprises a rectangular housing with at least two plate-type electrodes disposed opposite and parallel to one another, with an effective area of flow of which the corners of the rectangular housing are rounded by means of semiconducting material.  
     
     
         3 . Treatment apparatus according to  claim 2 , wherein the semiconducting material is solid and its conductivity matches the conductivity of the food products to be treated.  
     
     
         4 . Treatment apparatus according to  claim 2 , wherein the semiconducting material comprises one or more compartments in which a liquid material is present.  
     
     
         5 . Treatment apparatus according to  claim 4 , wherein the liquid material is selected from a liquid component of the food products to be treated.  
     
     
         6 . Treatment apparatus according to  claim 2 , wherein the plate-type electrodes are provided with end sections which extend outwards.  
     
     
         7 . Treatment apparatus according to  claim 6 , wherein the end sections have a curved end face.  
     
     
         8 . Treatment apparatus according to  claim 2 , wherein the electrodes extend on both sides, in the direction perpendicular to the flow direction, beyond the effective area of flow.  
     
     
         9 . Treatment apparatus according to  claim 8 , wherein the electrodes have rounded lateral sections.  
     
     
         10 . Treatment apparatus according to  claim 1 , wherein a number of separate first electrodes, which are electrically insulated from one another, are disposed across a first section of the circumference of the treatment chamber and a number of separate second electrodes, which are electrically insulated from one another, across a second section of the circumference, the potential controller of said electrodes being of such design that the potential (V) of each electrode is separately controllable so that the field strength (E) in the effective area of flow is kept constant.  
     
     
         11 . Treatment apparatus according to  claim 10 , wherein the first electrode(s) and second electrode(s) extend parallel to the longitudinal centre line of the treatment chamber and over the length thereof.  
     
     
         12 . Treatment apparatus according to  claim 11 , wherein the electrodes have a crescent-shaped cross section of which one side has a radius of curvature which matches the radius of curvature of the effective area of flow, said side forming part of the internal perimeter of the treatment chamber.  
     
     
         13 . Treatment apparatus according to  claim 10 , wherein the electrodes are disposed so as to be distributed at regular intervals over the circumference.  
     
     
         14 . Treatment apparatus according to  claim 1 , wherein the potential controller is of such design that the direction of the electric field can be rotated through 90°.  
     
     
         15 . Treatment apparatus according to  claim 1 , wherein the ratio of the spacing between the electrodes to the maximum width of the effective area of flow is 2:3.  
     
     
         16 . Treatment apparatus according to  claim 1 , wherein the ratio of the length L of the treatment chamber to the spacing D between the electrodes is at least 3:2.  
     
     
         17 . Method of preserving food products by subjecting them to a pulsed electric field between at least two electrodes in a treatment apparatus, wherein the direction of the electric field in successively applied pulses is rotated through 90°.