The potential of plasma-processed air (PPA) for industrial food safety in herbs and spices

Yao, Y., Meister, M., Zuber, S., Nierop Groot, M. N., den Uijl, K., Linthorst, M., Hoogland, H., Ehlbeck, J., Schnabel, U. and Karatzas, K.-A. G. (2026) The potential of plasma-processed air (PPA) for industrial food safety in herbs and spices. Innovative Food Science and Emerging Technologies, 110. 104494. ISSN 1878-5522 doi: 10.1016/j.ifset.2026.104494

Abstract/Summary

Non-thermal plasma is gaining attention for food decontamination due to effective microbial inactivation, minimal quality deterioration, reduced energy consumption compared with thermal treatment. However, the lack of upscaled equipment suitable for industrial production has limited its transfer from lab to industry. The present study aims to validate the production efficiency of reactive species of an upscaled microwave plasma source – _PLexc2. Fourier transformation infrared (FTIR) spectroscopy was applied for the chemical characterization and quantification of long-living reactive species in PPA. PLexc2 could deliver 15,412, 13,263, and 11,522 ppm of NOx (sum of NO2 and NO) at flow rates of 63, 73, and 83 L/min, respectively. Throughout a 60- min PLexc2 operation, the temperature in the treatment chamber remained within the range of room temperature (20–25 ◦C). PPA treatment was then tested against Enterococcus faecium inoculated on crushed oregano leaves. For 1- and 30-min PPA treatments, 1.90 log10 and 4.49 log10 reductions were achieved, respectively. One hour of post-discharge sample incubation in the treatment chamber, in addition to a 1-min PPA treatment, increased the reduction from 1.90 log10 to 3.21 log10. The economic feasibility was assessed by estimating conversion costs of PPA treatment, which ranged from 0.04 to 80.60 €/kg depending on treatment mode and scale. The return on capital investment of PLexc2 equipment was estimated to be less than one year for a production quantity of 2000 t/yr. In conclusion, this study demonstrates the potential and the economic feasibility of applying an upscaled microwave plasma source in the food industry.

Item Type	Article
URI	https://centaur.reading.ac.uk/id/eprint/128578
Identification Number/DOI	10.1016/j.ifset.2026.104494
Refereed	Yes
Divisions	Life Sciences > School of Chemistry, Food and Pharmacy > Department of Food and Nutritional Sciences > Food Microbial Sciences Research Group
Publisher	Elsevier
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