Mechanism of action of pulsed high electric field (PHEF) on the membranes of food-poisoning bacteria is an ‘all-or-nothing’ effect

Salmonella typhimurium (CRA 1005) was more sensitive than Listeria monocytogenes (NCTC 11994) to pulsed high electric field (PHEF) treatment in distilled water (10, 15 and 20 kV/cm), 10 mM tris-maleate buffer pH 7.4 (15 kV/cm) and model beef broth (0.75% w/v; 15 kV/cm). Sublethal injury could not be detected using a selective medium plating technique, indicating that bacterial inactivation by PHEF may be an ‘all-or-nothing’ event. PHEF-induced membrane permeabilization resulted in increased UV-leakage and a decreased ability of L. monocytogenes to maintain a pH gradient.