Bactericidal Effects against S. aureus and Physicochemical Properties of Plasma Activated Water stored at different temperatures

Abstract

Water activated by non-thermal plasma creates an acidified solution containing reactive oxygen and nitrogen species, known as plasma-activated water (PAW). The objective of this study was to investigate the effects of different storage temperatures (25 °C, 4 °C, −20 °C, −80 °C) on bactericidal activities against S. aureus and physicochemical properties of PAW up to 30 days. Interestingly, PAW stored at −80 °C yielded the best antibacterial activity against Staphylococcus aureus, 3~4 log reduction over a 30-day period after PAW generation; meanwhile, PAW stored at 25 °C, 4 °C, and −20 °C, respectively, yielded 0.2~2 log decrease in cell viability after the same exposure and storage time. These results were verified by scanning electron microscope (SEM). The physicochemical properties of PAW stored at different temperatures were evaluated, including pH, oxidation reduction potential (ORP), and hydrogen peroxide, nitrate, nitrite anion and NO radical levels. These findings suggested that bacterial activity of PAW stored at 25 °C, 4 °C, −20 °C decreased over time, and depended on three germicidal factors, specifically ORP, H2O2, and NO3−. Moreover, PAW stored at −80 °C retained bactericidal activity, with NO2− contributing to bactericidal ability in association with H2O2. Our findings provide a basis for PAW storage and practical applications in disinfection and food preservation.

Microbial decontamination of stainless steel and polyethylene surfaces using GlidArc plasma activated water without chemical additives

“…Thus, the synergistic effects of acid pH and ROS and RNS are a guarantee of a good germicidal action of PAW. These findings are consistent with Traylor et al ., and Shen et al ., who showed that the action of DBD air PAW on S. aureus and Escherichia coli bacteria, respectively, was effective only at acidic pHs.…”

“…The nitrite, nitrate and peroxide contents obtained were therefore at this pH. Previous works on activated water generated by other types of discharge also have proved the formation of these species, even if the contents varied from one study to the other, depending on the duration of the discharge and the plasma gas.…”

Nonthermal Plasma–Liquid Interactions in Food Processing: A Review

“…In‐water application of plasma using air as a carrier gas produced both atomic oxygen and atomic nitrogen species in the activated water. Atomic oxygen species, in turn, produced O 3 , OH, and H 2 O 2 , whereas the atomic nitrogen formed nitrites, nitrates, S‐nitrosothiols, and nitrosamines in PAW (Shen et al., ). Further, the emission intensity of plasma and ORP of treated water is greater when the plasma is produced inside the water when compared to above‐water treatment (Tian et al., ).…”

“…Shen et al. () called PAW as a “green disinfectant” because it has a less adverse impact on the environment than chemical agents and proposed it as a promising food sanitizer.…”

Applications of cold plasma technology for microbiological safety in meat industry

“…phase are also decided by the storage temperature (Shen, et al, 2016). Therefore, 252 appropriate temperature of storage should be ensured as a hurdle to prevent recovery of 253 cell activity.…”