Bacterial decontamination of liquids with pulsed electric fields

The effect of pulsed electric fields on the viability of microorganisms, mainly bacteria, in liquids has been studied since the 1960's. Experimental results obtained over a large range of electrical and microbiological parameters, point towards an irreversible formation of pores in the cell membrane as mechanism for lysing. The model of membrane pore formation seems to fail only for ultrashort electrical pulses, where intracellular effects, and possibly resonant effects, might dominate. This paper presents an overview of the effect of pulsed electric fields on the viability of microorganisms in 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 and drinking water. The energy consumption for complete bacterial decontamination is presently 100 to 400 kj/l. A possible reduction of the required energy by utilizing intracellular electric field interactions and resonance effects is discussed.