Surface decontamination of eggshells by using non-thermal atmospheric plasma

In this study, the possibility of using an effective short time non-thermal plasma (NTP) treatment to inactivate Salmonella enterica serovar Enteritidis on eggshell surface was investigated. The eggshells were artificially contaminated with S. Enteritidis at an initial concentration of 107 cfu/egg and then treated with an atmospheric pressure plasma jet by using air as process gas under different experimental settings with various frequencies (20-25 kHz) and reference voltages (100-80%), exposure times (60-120 s), distances from plasma jet (15 or 40 mm) and gas flow rates (2000-3000 L/h). The best result was obtained at maximum plasma power of 655 W (25 kHz-100% V), where S. Enteritidis concentration on egg surface was reduced below the detection limit (102 cfu/egg) after 120 s of treatment. The temperature remained below 35 °C after all plasma treatments in order to minimize the risk of egg quality alterations. Specific measurements demonstrated that there were no negative effects on egg quality after NTP treatment. The effect of plasma process on the egg cuticle was demonstrated by using scanning electron microscopy.