Fundamental and Applied Aspects of Pulsed Electric Fields for Microbial Inactivation

Abstract

Abstract-Pulsed electric field (PEF) is a technology that causes electroporation of the cell membranes by application of intermittent electric fields of high intensity for short periods of time (µs). The local defects or pores created by the application of an external electric field may lead to the loss of the membrane integrity and uncontrolled molecular transport across microbial membranes. These events may abolish the microbial capacity to maintain the microbial homeostasis causing microbial inactivation at temperatures below those used in thermal processing. Based in this phenomenon PEF provides an excellent alternative to conventional thermal pasteurization of heat sensitive foods.

Heat-Assisted Pulsed Electric Field Treatment for the Inactivation of Saccharomyces cerevisiae: Effects of the Presence of Citral

“…The electroporation of cell membranes results in alteration of cell membrane permeability and integrity and subsequently in the molecular exchange between cytoplasm and external medium across the lipid membrane. Thus, there is a decrease in the capacity of microbial cells to maintain homeostasis, causing the inactivation of vegetative cells at temperatures below those used in conventional thermal processing (Álvarez et al, 2006; Raso, 2016; Djukic-Vukovic et al, 2017).…”

Moderate and high intensity pulsed electric fields : Effect on microbial inactivation, shelf life and quality of fruit juices

“…Due to the electroporation effect, the permeability of the cell membrane increases (electropermeabilization) and, depending on the applied electric field strength, leads to either cell death (irreversible, complete inactivation) or resealing of the cell membrane and recovery (reversible, sub-lethal or partial inactivation) (Saulis, 2010). It is assumed that at least an electric field strength of 5 − 10 kV/cm is required to cause electroporation of the microbial cell membrane irreversibly (Jaeger et al 2016;Raso, 2016).…”

“…The external electric field strength required to reach the transmembrane voltage threshold is known as critical electric field strength (E c ), and when E > E c , electroporation is induced (Álvarez, Condón & Raso, 2006). For microbial cells (1 -10 µm) an electric field strength > 10 kV/cm is required to induce electroporation, while for eukaryotic plant cells (40 -200 µm) an electric field strength < 5 kV/cm is sufficient (Raso, 2016). When the electric field strength is much higher than the critical electric field strength, or applied for a sufficient long treatment time, electroporation is irreversible ( Fig.…”

“…Moderate intensity PEF conditions, defined in this study as conditions with an electric field strength E < 5 kV/cm, have been extensively studied as a pre-step in mass transfer phenomena in food and biotechnological processes, aiming to mildly disintegrate plant cells (Donsì, Ferrari & Pataro, 2010). Although the electroporation effect in plant cells was observed, these process conditions have received no attention for the application as alternative preservation process to inactivate micro-organisms, probably due to their small size (1 − 10 µm) compared to the size of eukaryotic plant cells (40 − 200 µm) (Raso, 2016). The use of moderate intensity PEF conditions has been studied in biology applications for gene transfer, and showed electroporation effects in microorganisms, when exposure time was long enough (Eynard et al, 1998).…”

“…PEF is a technology that causes electroporation of the cell membrane by application of intermittent electric fields of high intensity for a short period of time (Raso, 2016), ranging from microseconds to milliseconds. In liquid foods, electric pulses are delivered into the fluid using two electrodes where the liquid is in electrical contact with both electrodes or alternatively for solid foods coupled to them via an electrically conductive medium.…”