Non-thermal plasma technology is recognized for its strong antimicrobial efficacy on food and food production environment-associated microorganisms and its ability to enhance food safety and food shelf-life [1]. However, the lack of scientific knowledge regarding the differences in physical and chemical processes at various upscaling levels hinders the successful transition of this technology from laboratory settings to industrial applications [2]. Hence, the aim of this study is to study the association between plasma-processed air (PPA) composition and its antimicrobial effects, as well as the underlying mechanism of action. This research focuses on three different air plasma torch devices, each representing a distinct stage of upscaling. A microwave plasma torch operated with compressed air delivers PPA as an antimicrobial-acting process gas. Three air plasma torch devices were applied and optimized to study the association between PPA composition and its antimicrobial effects. By employing advanced analytical methods like Fourier transform infrared spectroscopy (FTIR), a comprehensive analysis of PPA’s characteristics was carried out. Key reactive nitrogen species (RNS) in the PPA were identified via spectroscopic measurements for the lab-size device MidiPLexc. From the spectrum, nitrogen monoxide (NO), nitrogen dioxide (NO2), and dinitrogen pentoxide (N2O5) were detected, where NO2 took up more than 70 % in a quantity of the key reactive species [3]. Input power and relative humidity were found to have an impact on the species concentration. The findings of this study will provide valuable insights into the physical and chemical factors that affect the scalability of non-thermal microwave plasma for antimicrobial processes. The knowledge gained will accelerate the development and application of non-thermal atmospheric pressure plasma as a highly promising alternative for disinfection and cleaning purposes.
Author Contributions
Conceptualization, Y.Y., U.S. and J.E.; methodology, Y.Y.; formal analysis, Y.Y.; investigation, Y.Y.; writing—original draft preparation, Y.Y.; writing—review and editing, U.S. and K.-A.K.; supervision, U.S., J.E., and K.-A.K.; project administration, U.S. and J.E.; funding acquisition, U.S., J.E., and K.-A.K. All authors have read and agreed to the published version of the manuscript.
Funding
This project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska Curie grant agreement No 955431.
Institutional Review Board Statement
Not applicable.
Informed Consent Statement
Not applicable.
Data Availability Statement
The data presented in this study are available on request from the corresponding author. The data are not publicly available due to ongoing work.
Conflicts of Interest
The authors declare no conflicts of interest.
References
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