A device for combined thermal and pulsed electric field treatment of food

The application of pulsed electric fields to biological tissue enables both ohmic heating of the material and a permeabilisation of the biological cells at ambient temperature due to electroporation. To what extend each of both mechanisms is effective can be controlled via the applied electric field strength and duration of treatment. A device for batch treatment of biological material with pulsed electric fields for studying both effects has been set up and tested successfully. It comprises a pulse circuit based on a RLC circuit and a 30-stage Marx generator with IGBT switches. The generator has been designed with only one closing switch per stage, capable of active voltage clamping. The charging voltage per stage and pulse current are 1 kV and 500 A, respectively. Soft-switching conditions of the IGBTs are ensured by the inductance of the circuit. The operation of the device has been demonstrated with a combined treatment of an apple by electroporation and ohmic heating.