Plasma activated water prepared by different plasma sources: physicochemical properties and decontamination effect on lentils sprouts

Abstract

The pulsed corona discharge (CD) generated in contact with water and directly in water, and high-power air plasma jet (APJ) were studied for production of plasma activated water (PAW). The changes of physical (pH, redox potential, conductivity, temperature) and chemical (peroxides, nitrites, nitrates concentrations) properties of treated water were investigated. The comparison of CD generated in gas/water interface and underwater configuration in the same system showed that the interaction of reactive oxygen and nitrogen species formed in ambient air in gas/water system induces different chemical processes, leading to lower pH, higher oxidation-reduction potential (ORP) and higher conductivity of PAW than in underwater discharge. High yield of peroxide was observed in both configurations. The PAW prepared by APJ exhibits high concentration of nitrites and nitrates according to supplied energy, and related significant decrease of pH and increase of ORP and conductivity after treatment. The antimicrobial effect of PAW prepared by CD and plasma jet on lentils sprouts was studied in different treatment and washing times. The APJ appears to have great efficacy on water activation resulted in strong decontamination effect. The PAW treated by APJ for 10 min led to bacterial reduction from initial 8.3 to 5.9 and 4.0 log10 CFU g−1 after 10 and 30 min of washing, respectively.

Effect of different process conditions on the physicochemical and antimicrobial properties of plasma-activated water

“…All of the results indicated that changing the treatment time and solution volume could significantly (P < 0.05) affect the physical parameters of PAW. The conductivity and ORP showed opposite trends to the pH of PAW under the same treatment conditions, because H + has a higher mobility than OH − ions [20,25].…”

“…and H + , were produced with a prolonged preparation time, resulting in a new chemical reaction to acidify the solution [18]. However, some studies have shown that the pH of PAW reaches a constant state after a certain long treatment time, and results are easily affected by the equipment used [19,20].…”

Effect of air, O2, Ar, and N2 plasma‐activated water on mildewing activity of moldy pathogen of Gannan navel oranges

“…Xu et al [ 23 ] found that PAW soaking of Agaricus bisporus mushrooms could effectively reduce their microbial population during storage and delay mushroom softening. Medvecka et al [ 24 ] found that washing lentil sprouts with PAW effectively reduced the number of bacteria and had a strong decontamination effect. However, there are almost no studies on the inactivation of fungi causing navel orange rot by PAW, while only a few studies [ 21–24 ] reported on the inhibition of the mildewing activity of pathogenic spores by PAW.…”

“…Xu et al [23] found that PAW soaking of Agaricus bisporus mushrooms could effectively reduce their microbial population during storage and delay mushroom softening. Medvecka et al [24] found that washing lentil sprouts with PAW effectively reduced the number of bacteria and had a strong decontamination effect. However, there are almost no studies on the inactivation of fungi causing navel orange rot by PAW, while only a few studies [21][22][23][24] reported on the inhibition of the mildewing activity of pathogenic spores by PAW.…”

Comparison of the Effect of Plasma-Activated Water and Artificially Prepared Plasma-Activated Water on Wheat Grain Properties

“…According to some studies [ 44 ], the presence of certain metal ions, especially copper and zinc, can also have a significant impact on the effectiveness of activated water. Medvecká et al [ 45 ] described the dependence of the composition of reactive particles in PAW on the experimental conditions of its preparation, namely the type of plasma source and its parameters and the composition of the working gas.…”