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Influence of plasma characteristics on the efficacy of Cold Atmospheric Plasma (CAP) for inactivation of Listeria monocytogenes and Salmonella Typhimurium biofilms

Govaert, Marlies, Smet, Cindy, Vergauwen, Laurens, Ećimović, Branimir, Walsh, James L., Baka, Maria, Van Impe, Jan
Innovative food science & emerging technologies 2019
Listeria monocytogenes, Salmonella Typhimurium, bacteria, biofilm, cleaning, disinfection, electric potential difference, electrodes, food contamination, foods, oxygen
The biofilm mode of growth protects bacterial cells from applied disinfection methods for abiotic (food) contact surfaces. Therefore, new inactivation technologies such as Cold Atmospheric Plasma (CAP) should be considered. However, the influence of different plasma characteristics on the CAP efficacy for biofilm inactivation requires further study. In this research, the influence of (i) the applied plasma configuration (Dielectric Barrier Discharge (DBD) and Surface Barrier Discharge (SBD)), (ii) the oxygen level of the gas flow (He + 0.0/0.5/1.0 (v/v) % O2), and (iii) the plasma intensity (13.88, 17.88, and 21.88 V input voltage) on the CAP efficacy for inactivation of L. monocytogenes and S. Typhimurium biofilms was investigated. Depending on the applied plasma characteristics, log10-reductions up to approximately 3.5 log(CFU/cm2) were obtained. Nevertheless, it could be concluded that the highest log-reductions were in general obtained while using the DBD electrode, 0.0 (v/v) % O2, and an input voltage of 21.88 V.This study demonstrated the potential application of CAP for inactivation of pathogenic biofilms developed on abiotic (food) contact surfaces. The effect of different plasma characteristics on the CAP inactivation efficacy was investigated and determined optimal conditions resulted in promising reductions of the biofilm-associated cells. By incorporating this novel technology in a complete cleaning and disinfection process, the risk of (cross) contamination of food products might extensively be reduced.