Evaluation of plasma‐activated water characteristics and its process optimization

Abstract

AbstractPlasma‐activated water (PAW) is an emerging technology for the disinfection of foods and it is also widely evaluated for its applications in medicine. The long‐lived reactive oxygen species such as hydrogen peroxide and ozone are mainly responsible for the disinfecting properties of Ar/O2 PAW. In this study, PAW characteristics were evaluated with respect to the process conditions and the post‐treatment time to understand the effect of process conditions and the time stability of PAW. PAW was generated using a continuous flow dielectric barrier discharge Ar/O2 atmospheric pressure plasma system at different PAW treatment times. PAW properties were evaluated based on the concentration of hydrogen peroxide, ozone, pH, and the disinfection of Escherichia coli. From the time stability analysis, it was found that the hydrogen peroxide was more stable than ozone in PAW when stored at room temperature for 2 days. The E. coli inactivation was mainly attributed to the H2O2 and ozone concentration than pH. The optimum process condition was found as 104 ml/min water flow rate, 20‐min treatment time and 4 slm gas flow rate for maximum reactive species concentration in PAW.Practical ApplicationsThere is a need for non‐chemical disinfection method of fresh fruits and vegetables, as the present chemical‐based disinfection methods are inefficient in controlling food‐borne outbreaks and the residual toxicity of these chemicals. Plasma‐activated water (PAW) is an emerging technology, which has the potential in disinfecting microorganisms. The aim of the work was to analyze the disinfection properties and the time stability of PAW. It is evident from the results that PAW is effective in disinfecting Escherichia coli and its reactive species degrade with time. This will facilitate the application of PAW as a disinfectant for fresh fruits and vegetables without any residual toxicity to the food and the environment. Further, from the optimization studies, understanding of the influence of process parameters on the PAW characteristics was derived which will be helpful to scale‐up of this technology.