Impact of species and strain variability on non-thermal plasma decontamination efficacy

Microwave non-thermal plasma (NTP) is a promising preservation technology for surface decontamination, alternative to conventional methods such as heat treatments and chemical additives. This study explores the impact of plasma processed air (PPA) exposure on 50 strains from five diverse microbial species relevant to food quality and safety. Bacterial vegetative cells were effectively inactivated in an agar plate model system. The average reduction after 60 s of treatment was 4.9 log10, 5.8 log10, and 5.9 log10 for Listeria monocytogenes, Escherichia coli, and Lactiplantibacillus plantarum respectively, with limited strain variability. Saccharomyces cerevisiae reached an average of 5.3 log10 reduction after 30 s of treatment, with one resistant strain (AD1890). Bacillus subtilis spores were inactivated by 2.0 log10 on average after 30 min, with two distinct strain groups. These results showed that PPA can be used as a mild decontamination treatment applicable to dry and heatsensitive surfaces, suitable for various food applications.