Effect of the Inclusion of Magnesium Ions During Generation Process of Plasma‐Activated Water on Disinfectant Efficacy and Sustainability

In this study, PAW was generated using an argon plasma jet in the presence and absence of magnesium plates as a source of Mg 2+ ions. The physicochemical properties of PAW were characterized by measuring pH, oxidation‐reduction potential, electrical conductivity, and the concentrations of H₂O₂, NO₂ − , and NO₃ − during generation and subsequent storage. Results demonstrated that PAW without Mg exhibited higher OR P values (≈420 mV) and lower pH (5.3–5.7), while PAW Mg maintained a near‐neutral pH (6.2–6.4) and significantly lower ORP (≈75–275 mV). Hydrogen peroxide levels were generally higher in PAW without Mg during most of the generation period (10–50 min), whereas PAW Mg retained slightly higher concentrations at the 60‐min endpoint, indicating a stabilizing effect of magnesium on reactive species. PAW Mg also showed slower degradation of RONS during the aging period, confirming its superior stability. The antimicrobial activity of both PAW types was evaluated against six planktonic bacterial strains, including Gram‐negative ( Escherichia coli O157:H7, Salmonella enteritidis , Pseudomonas aeruginosa ) and Gram‐positive ( Staphylococcus aureus , Listeria monocytogenes , Bacillus cereus ). PAW Mg achieved total inactivation (≈8 log₁₀ reduction) of all species within 24 h, while PAW without Mg also demonstrated strong bactericidal efficacy, with reductions above 5 log₁₀ for all tested bacteria after 24 h. Gram‐positive strains were generally more resistant, with B. cereus showing the lowest susceptibility. Scanning electron microscopy revealed pronounced membrane damage and morphological alterations, particularly in cells treated with PAW Mg, consistent with the higher bactericidal efficiency of this treatment. Overall, Mg 2+ incorporation reduced ORP but stabilized reactive species, extending antimicrobial activity and improving efficacy. PAW Mg emerged as a more stable disinfectant, while PAW without Mg also showed strong microbial inactivation, supporting their potential in food safety and environmental use.