A continuous treatment system for inactivating microorganisms with pulsed electric fields

High voltage pulsed electric fields (PEF) can be used to inactivate microorganisms in liquids. Applying this PEF technology to food pasteurization is a promising nonthermal method, which may radically change food preservation processes and provide consumers with microbiologically safe, minimally processed, fresh-like products. A continuous-flow system in laboratory-size prototype was constructed for the nonthermal pasteurization of liquid foods with PEF technology. Major components in the prototype include a high voltage repetitive pulse generator, a coaxial liquid food treatment chamber, a fiber optic temperature sensing instrument, and a data acquisition system. Microbial inactivation tests were conducted in the continuous PEF treatment system. Repetitive high voltage pulses with an exponential decaying waveshape were applied to the liquid food which was pumped through the treatment chamber. Test microorganisms selected for inactivation were: Escherichia coli; Staphylococcus aureus; and Saccharomyces cerevisiae. Over six order-of-magnitude reductions in the viability of selected microorganisms were achieved when the food temperature was maintained below 40°C