Decontamination effects of the plasma gun tested on various surfaces

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The microbial contamination of fresh food is a remarkable problem as there aren´t sufficient methods to guarantee an effective decontamination without lessening the food quality. Thus, usage of CAP may be very beneficial for surface decontamination of meat or fresh fruit and vegetables as well as for the decontamination of the working areas. The food industry involves interactions of CAP with many different materials, which is why the agar, the pork skin and the polylactic acid polymers (PLA) were chosen as model inoculation substrates. This work studies the interaction of CAP, specifically the plasma gun, with the selected surface materials with the intention of decontamination. As there have been many studies done on bacteria, this work challenges the plasma systems by the exposure to yeast and even cocultures (yeast with bacteria). As model microorganisms, gram negative bacteria Escherichia coli and gram-positive Staphylococcus epidermidis and the yeast Candida glabrata were chosen. The preliminary tests were done on Petri dishes to establish the basic plasma parameters. Several experiments were carried out on the different surfaces for individual bacteria (E. coli, S. epidermidis), yeast (C. glabrata) and even their coculture (yeast with bacteria). In addition to classic plasma diagnostics, different ozone measurements were done to support the estimations about the inhibition mechanisms. The combined action of short-lived species in cooperation with the long-lived species was studied and several treatment modes were established to achieve the most efficient decontamination. The treatment of coculture and the use of different inoculation substrates moves us closer to real life situation, where the food is contaminated by a mixture of different microbes interacting with each other. The results confirm the dependence of the inhibition efficacy on the target properties, but even on the dielectric surface (PLA) it was possible to achieve decent microbial reduction.

antimicrobial effects, Candida glabrata, CAP, cold plasma, direct treatment

TREBULOVÁ, K.; KOZÁKOVÁ, Z.; MENČÍK, P.; POUVESLE, J.-M.; STANCAMPIANO, A.; ROUILARD, A.; ROBERT, E.; HRUDKA, J; KRČMA, F.

20. 5. 2024

Instutute of Physics RAS

Belgrade

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