A solid state pulsed power system for food processing

In 2000, Diversified Technologies, Inc. (DTI) of Bedford, MA designed, built, and installed the first commercial scale pulsed electric field (PEF) system at Ohio State University's Department of Food Technology. This PEF system is part of a new food treatment system assembled by a DoD sponsored, university-directed industry consortium. The purpose of the program is to research the use of high voltage pulsed power to kill microorganisms, including pathogens, in liquid foods such as juices. The process, called pulsed electric field processing (PEF), maintains the fresh taste of foods lost in heat pasteurization, because it is nonthermal. This solid state pulsed power system provides bipolar 60 kV, 600 A pulses at 75 kW average power into four PEF treatment chambers. It consists of two fully independent switching power supplies and solid state switches-one at positive voltage, and the other at negative voltage. This provides a very high level of pulse flexibility to the OSU researchers as they optimize PEF treatment parameters across a wide range of liquid foods. In this paper we will describe the architecture of the pulsed power system and the application and benefits of solid state high voltage systems to food sterilization. Operational results and status will also be presented.