Inactivation of Salmonella enteritidis in liquid whole egg using combination treatments of pulsed electric field, high pressure and ultrasound

The effects of pulsed electric field (PEF), hydraulic high pressure (HHP) and ultrasound alone and in combinations on inactivating Salmonella enteritidis in liquid whole egg were investigated. The optimum conditions were: PEF-30 pulses of 5.67 kV/mm (+ ve peak) at 55 degrees C, HHP-2-2-4 min cyclic treatment at 138 MPa and 20 degrees C, and ultrasound-40 W at 55 degrees C for 5 min. The PEF was not effective due to high viscosity of the egg. The use of HHP in multiple cycles was better than single treatments of equivalent time. Increasing the exposure time to ultrasound resulted in greater microbial reductions. Increasing the temperature increased the effectiveness of ultrasound. Treatment combinations only exhibited additive effects. No synergy was observed. A combination of high pressure and ultrasound treatments resulted in the greatest microbial reduction of 3.2 log cycles and, with the addition of mild heat, provides an alternative to thermal processing where high temperature has caused protein coagulation. (c) 2006 IAgrE. All rights reserved Published by Elsevier Ltd.