Effects of atmospheric cold plasma on microbial growth of Listeria innocua and Staphylococcus aureus in ready-to-eat fish products

Food-borne pathogens, including Staphylococcus aureus and Listeria monocytogenes, in fish products account for death to a great extent. To increase shelf-life of foods and also preserve their sensory properties, plasma treatments have attracted more attention. The present study was intended to investigate the efficacy of atmospheric cold plasma (ACP) using argon and helium gas flows for ready-to-eat (RTE) fish products contaminated with L. innocua and S. aureus at short treatment durations of 4, 6 and 10 min. The results showed that argon plasma at each time point (4, 6, and 10 min) had a significantly inhibitory effect on the growth of L. innocua. Also, it reduced over a 10-minute treatment with helium plasma. There was a direct correlation between exposure time and antimicrobial efficiency of argon and helium ACP. The survival of S. aureus decreased by 0.19-1.04 Log cycles after argon plasma whereas helium plasma had a lower potential for growth reduction within the range of 0.03 and 0.55 Log cycles. It could be concluded that ACP is effective for lowering growth of different micro-organisms on RTE fish samples. L. innouca was considerably more sensitive than S. aureus to atmospheric pressure plasma (APP).