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

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 log(10) CFU g(-1) after 10 and 30 min of washing, respectively.