Reduction of Escherichia coli O157:H7 on goat meat surface with pulsed dc square wave signal

Pulsed dc square wave electric signal was applied to goat meat samples, inoculated with Escherichia coli O157:H7 on the surface, covered with a thin film of 0.15 M sodium chloride solution. Experiments were conducted with 10, 20 and 30 mA/cm(2) current intensities for 2, 8 and 32 min of treatment durations. Effects of 100, 1 k and 10 kHz frequency signals were tested for the survival of E. coli with 20 mA/cm(2) and 80% duty cycles. Three duty cycles of 30, 50 and 80% at I kHz frequency and 20 mA/cm2 were applied to test the inactivation rate of E coli. The results indicated that all three intensities of current effectively inactivated E coli cells at treatment duration of 32 min. Eight log(10) reductions per ml of E coli cells were achieved. A decrease in treatment duration decreased log(10) reduction of E coli. Frequencies of 1 kHz or more and duty cycles of 50% or more accelerated the inactivation of E coli cells at 20 mA/cm(2) current. (c) 2005 Elsevier Ltd. All rights reserved.