Antimicrobial activity of cold plasma against E. coli and Listeria inoculated on raw meats, deli and produce

Consumers trends indicate an increased demand for “all natural” and “no artificial” chemicals in foods while the food industry is working diligently to ensure food safety while complying with the stringent food safety standards. We investigated the application of cold plasma as an innovative technology conforming to the consumer demands while ensuring food safety.  

Raw beef (4 sq. cm) and the lunch meat (ham) (1.6 sq. cm) were inoculated with of 10⁷ E. coli K-12 and Listeria innoca, respectively and exposed to cold plasma for 0, 5, 10 and 15 minutes. Lettuce dip inoculated with 10⁵coliK-12 was washed in various solutions: tap water, 150ppm chlorine, 0.84% WMEO + 0.1% Carvacrol + 2% Acetic acid, and the leaves were then subjected to 0, 5 and 10 min cold plasma exposure.  Post-treatment, the raw beef, lunch meat and lettuce samples were analyzed for the levels of E. coli and Listeriaspp and the bacterial reductions and color were compared using ANOVA.

Cold-plasma treatment significantly (P<0.05) reduced the levels of inoculated E. coli and Listeria in all the food matrices. Cold plasma treatment for 5 min caused a 1.75 and 1.02 log reduction of E. coli on raw beef and Listeriaon ham, respectively. Exposure to cold plasma after a WMEO wash increased the E. colikill by approximately 1.2 logs without significant effects on leaf color.

Cold plasma can be used as an effective antimicrobial intervention to improve food safety and must be investigated further.