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Recent development in PEF equipment |
Q. H. ZHANG, Dept. of Food Science & Technology, Ohio State Univ., 2015 Fyffe Ct., 233 Parker Food Science Bldg., Columbus, OH 43210-1007 Pulsed electric field (PEF) processing research has been limited by the availability of equipment. Recent advancement in semiconductor switch technologies has made PEF equipment smaller in size, more reliable and less costly. This paper report recent progress made in design, fabrication and operation of PEF processing equipment. New semiconductor switches, Integrated Gate Bipolar Transistor (IGBT), is available in specifications of 1200 to 1700 volt and 1200 to 2400 amperes, corresponding to 1 - 5 MW of peak power. Series or parallel configurations are practical to increase the peak power to the range of 20 to 60 MW for plant scale PEF operation. A direct discharge to the chamber is utilizes the series configuration while a step-up pulse transformer utilizes the parallel configuration. Over current protection is easily incorporated into the local drive circuit of the IGBT. Integrating the high voltage pulse generator with the PEF chambers and appropriate product handing components is a major development. Knowledge and experience from aseptic processing are adapted to the design of integrated PEF systems. HACCP and GMP principles are incorporated in the operational procedures. New PEF systems designs also take into consideration operator safety, wet plant operation environment, power factor correction and easy maintenance. A PEF Consortium for Commercialization has commercial scale PEF system for evaluations and implementations.
Session 23, Pulsed electric fields: An update
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