Square pulse waveforms are more lethal and more energy efficient than

According to a white paper produced by the FDA, "Square pulse waveforms are more lethal and more energy efficient than exponential decaying pulses"

Apparently, it is important that the peak value be maintained 50 percent of the time. There was little mention of the importance of rise time ( slew rate ) but this is probably critical as well.

Among factors listed as being important are:



4.2. Methods to Measure Critical Process Factors

PEF critical process factors may be monitored as follows:

1) Pulse voltage waveform. The average electric field strength is calculated by dividing the peak voltage by the gap distance between the electrodes. A voltage probe and an oscilloscope make such measurement. Data logging is necessary to keep this critical process variable.

2) Pulse current waveform. Pulse current should have a waveform very similar to that of the voltage waveform, different by a ratio, the load resistance. In the case of a partial breakdown, the ratio changes. A shunt resistor or a current monitor, such as a Pearson Coil, together with an oscilloscope may be used to measure the current waveform.
3) Pulse duration time is determined from the voltage waveform.
4) Pulse repetition rate.

Another important note is in regards to specific microbe such as Candida: "S. cerevisiae and Candida spp. are 2 microorganisms of particular relevance in spoilage of foods. Although their inactivation has been proven in many food models and foods, their susceptibility to PEF may prevent their use as a surrogate."

In other words, This paper from the FDA recognizes that Candida as well as other microbes may be effectively inactivated by pulsed electric fields.


From: FDA-CFSAN Kinetics of Microbial Inactivation for Alternative Food Processing Technologies -- Pulsed Electric Fields.htm Tweet