Plasma-assisted systems for packaging decontamination

Foodborne diseases represent a persistent global challenge, causing millions of infections and significant economic losses every year. Conventional decontamination techniques in the food industry, such as thermal or chemical treatments, are effective but often unsuitable for heat-sensitive materials like polymeric packaging, while also raising environmental and safety concerns. Cold Atmospheric Plasma has recently emerged as a promising, electricity-based, and residue-free technology capable of achieving rapid and efficient microbial inactivation under mild conditions. This thesis presents the characterization, optimization, and technological diversification of a large-area Surface Dielectric Barrier Discharge system developed for food packaging decontamination. The work combines electrical, optical, thermal, and biological analyses to understand and improve system performance. The initial characterization demonstrated uniform plasma generation within a 17.5 L treatment chamber and consistent bacterial inactivation of 1–2 log reductions, independent of sample position. Subsequent optimization steps achieved up to 4.7 log reductions through process adjustments such as reduced chamber volume, increased duty cycle, and aerosol injection, highlighting the critical role of plasma–aerosol interaction in enhancing antimicrobial efficacy. To elucidate the underlying chemistry, advanced Fourier Transform Infrared spectroscopy was employed in both ex-situ and in-situ configurations. These analyses provided quantitative insights into the formation and evolution of reactive oxygen and nitrogen species in humid and aerosol-assisted plasmas, emphasizing the decisive influence of water in driving plasma-induced oxidation and acidification. Complementary hydrogel experiments further visualized the spatial distribution and penetration of reactive species, confirming the enhanced delivery of active compounds under aerosol-assisted operation. Finally, alternative DBD geometries, including coplanar, cylindrical, and mesh-based SDBD designs, were developed and characterized, demonstrating the versatility and scalability of plasma-assisted decontamination systems. Overall, this work establishes CAP as a viable, sustainable, and industrially relevant strategy for safe and efficient food packaging decontamination, paving the way for broader applications in food safety and environmental hygiene.