Assessment of the Physicochemical Properties and Biological Effects of Water Activated by Non‐thermal Plasma Above and Beneath the Water Surface

Abstract

A direct current atmospheric pressure cold plasma microjet (PMJ) was used to produce plasma activated water (PAW) in two generation modes above (PAW-A) and beneath (PAW-B) the water surface. The physicochemical characteristics and biological effects of them were measured respectively. Results showed that PAW-B exhibited stronger disinfection efficiency than PAW-A, which was associated with ORP and conductivity, but not pH value, temperature, H 2 O 2 , NO 3 À or NO 2 À . Furthermore, the cell membrane integrity and membrane potential of S. aureus were destroyed more severely by PAW-B. More importantly, a significant increase of intracellular ROS was induced by PAW-B, which was supposed to contribute most to the sterilization. This work provides valuable guidance for the production and wide applications of PAW.

Non-thermal plasma-activated water inactivation of food-borne pathogen on fresh produce

“…The value increased to 350 and 450 μS/cm after 10 and 20 min plasma activation, respectively. The result was consistent with our previous work [36], demonstrating that much active ions were generated in the PAW, which may be various ROS and other reactive species, playing important roles in the inactivation process.…”

“…The result indicated that a large amount of ROS was generated in PAW, which was consistent with our previous publications [35,36].…”

“…were achieved in the current researches where plasma discharge can lead to the acidification of treated water [35,36,49,50]. Although the pH of 10-PAW and 20-PAW is low, the critical pH to initiate S. aureus inactivation is 2 [51].…”

“…To improve energy efficiency, plasma discharge is formed over a liquid water surface, and the reactive species generated in the gas phase plasma can transfer into the liquid and possibly form reactive species in the liquid or liquid-gas interface [34]. It is generally agreed that the bactericidal activity of PAW derives from the combined action of a high positive oxidation reduction potential (ORP) and low pH [35,36]. There are two reasons to adopt PAW application.…”

“…On the other hand, PAW generated by plasma treatment of pure water, represent an environmentally friendly and cost-effective disinfectant comparing with the traditional chemical sanitizers, for example chlorine-based products associated with risks of carcinogenic by-products formation [38]. Previous studies have focused on the inactivation efficiency and mechanisms of PAW [32,[35][36], and there still have been no reports evaluating its inactivation effect on fresh produce.…”