Atmospheric pressure plasma jet treatment of Salmonella Enteritidis inoculated eggshells

- A significant and rapid reduction of S. Enteritidis on eggshells using an atmospheric pressure plasma jet is possible.
- A setting of Ar gas, a distance of 12 mm, a gas flow rate of 5 slm and an exposure time of 300 s was most effective.
- Longer exposure times led to higher reductions and Ar as feed gas was more effective than ArO2 mixtures.

Contamination of eggshells with Salmonella Enteritidis remains a food safety concern. In many cases human salmonellosis within the EU can be traced back to raw or undercooked eggs and egg products. Atmospheric pressure plasma is a novel decontamination method that can reduce a wide range of pathogens. The aim of this work was to evaluate the possibility of using an effective short time cold plasma treatment to inactivate Salmonella Enteritidis on the eggshell. Therefore, artificially contaminated eggshells were treated with an atmospheric pressure plasma jet under different experimental settings with various exposure times (15-300 s), distances from the plasma jet nozzle to the eggshell surface (5, 8 or 12 mm), feed gas compositions (Ar, Ar with 0.2, 0.5 or 1.0% O2), gas flow rates (5 and 7 slm) and different inoculations of Salmonella Enteritidis (101-106 CFU/cm2). Atmospheric pressure plasma could reduce Salmonella Enteritidis on eggshells significantly. Reduction factors ranged between 0.22 and 2.27 log CFU (colony-forming units). Exposure time and, particularly at 104 CFU/cm2 inoculation, feed gas had a major impact on Salmonella reduction. Precisely, longer exposure times led to higher reductions and Ar as feed gas was more effective than ArO2 mixtures.