Bacterial decontamination of liquids with pulsed electric fields

The effect of pulsed electric fields on the viability of microorganisms, ma inly bacteria, in liquids has been studied since the 1960's. Experimental r esults obtained over a large range of electrical and microbiological parame ters, point towards an irreversible formation of pores in the cell membrane as mechanism for lysing. The model of membrane pore formation seems to fai l only for ultrashort electrical pulses, where intracellular effects, and p ossibly resonant effects, might dominate. This paper presents an overview o f the effect of pulsed electric fields on the viability of microorganisms i n liquids. In particular, the lytic effect of variations in the electrical pulse parameters, such as pulse shape, amplitude, duration, and single shot vs. repetitive operation, is described. A major application of the pulsed electric field method is 'cold' bacterial decontamination of liquid food an d drinking water. The energy consumption for complete bacterial decontamina tion is presently 100 to 400 kj/l. A possible reduction of the required ene rgy by utilizing intracellular electric field interactions and resonance ef fects is discussed.