High intensity pulsed electric fields applied to egg white: Effect on Salmonella enteritidis inactivation and protein denaturation

Abstract

High-intensity electric fields have been successfully applied to the destruction of Salmonella Enteritidis in diaultrafiltered egg white. The effects of electric field strength (from 20 to 35 kV·cm-1), pulse frequency (from 100 to 900 Hz), pulse number (from 2 to 8), temperature (from 4 to 30°C), pH (from 7 to 9), and inoculum size (from 103 to 107 CFU·m1-1) were tested through a multifactorial experimental design. Experimental results indicate that, for Salmonella inactivation, the electric field intensity is the dominant factor with a strongly positive effect, strengthened by its positive interaction with pulse number. Pulse number, temperature, and pH have also significant positive effects but to a lesser extent. In the most efficient conditions, the pulsed electric field (PEF) treatment is capable of 3.5 1og10 reduction in viable salmonellae. Simultaneously, the measure of surface hydrophobicity does not indicate any increase after PEF treatment. These results suggest that no protein denaturation occurs, unlike what is observed after comparable heat treatment in terms of Salmonella inactivation (55°C for 15 min).