Inactivation of Escherichia Coli O157:H7 and Salmonella Enteritidis in Liquid Egg Using Continuous Pulsed Electric Field System

This study sought to evaluate the effect of PEF parameters such as electric field intensity and number of pulses on the inactivation of Escherichia coli O157:H7 and Salmonella Enteritidis suspended in liquid whole egg. The medium was inoculated with 108 CFU ml(-1) of E. coli O157: H7 or S. Enteritidis and was treated continuously at 10, 20 or 30 degrees C using electric field intensity of either 20 or 30 kV cm(-1). A biphasic instant reversal PEF waveform with up to 105 pulses of 2 mu s in width was applied. Bacterial inactivation increased with increasing applied electric field intensity, number of pulses and processing temperature. Maximum reductions of 3.9 and 3.6 log cycles were obtained for E. coli O157:H7 and S. Enteritidis, respectively. The maximum input energies required to inactivate E. coli O157:H7 and S. Enteritidis were 538 and 914 J, respectively. The higher kinetic value was obtained for S. Enteritidis (0.043 mu s(-1)) representing the more heat-PEF sensitive bacteria compared to E. coli O157:H7.