Antimicrobial activities of plasma-functionalized liquids against foodborne pathogens on grass carp (Ctenopharyngodon Idella).

Plasma-functionalized liquids (PFL) emerge as an effective sanitizer with great potential to be against a variety of microorganisms but their applications on seafood products are limited. In the current study, the physicochemical properties of plasma-functionalized water (PFW) and plasma-functionalized buffer (PFB), and their antimicrobial activities on grass carp, were investigated under different conditions of applied voltage, plasma exposure time and immersion time. Results indicated that increasing voltage and exposure time led to an increase in levels of reactive species in PFW and PFB, while the presence of citric acid in the buffer accelerated possible reactions of active species and enhanced acidification, electrical conductivity (EC) and oxidation-reduction potential (ORP) as compared with PFW. Results also showed that the decontamination efficiency depended on voltage and exposure time, which could be up to 1.21 and 1.52 log reductions for L. monocytogenes, and 1.44 and 1.75 log reductions for S. Typhimurium for PFW and PFB, respectively. Immersing fish fillet samples in both solutions also led to a reduced pH and increased total acidity level in the samples with no significant difference (p > 0.05) between PFW and PFB, while PFB greatly affected the colour change in fish fillets. This study provided a basis for the potential development of novel sanitizers to decontaminate microorganism in fish and seafood products.Key points• Cold plasma induced a time-dependent change of active species in water and buffer.• Ionic equilibria of conjugate base and weak acid in buffer enhanced RNS and ROS.• Decontamination depended on voltage and exposure time of liquids to cold plasma.• Reduced pH, increased acidity and colour change were noticed in treated fish.• A basis for developing potential sanitizers for seafood products is provided.