Modelling of inactivation kinetics of Escherichia coli, Salmonella Enteritidis and Bacillus subtilis treated with a multi-hollow surface dielectric barrier discharge plasma

Abstract

The efficacy of multi-hollow surface dielectric barrier discharge treatment against Escherichia coli, Salmonella Enteritidis and Bacillus subtilis was studied. Ambient air, O2, and N2 were used as working gas with a flow rate of 6 l/m. Power delivered into plasma was 30 W over an area of 2 × 2 cm2. The active species in plasma generated in different gases participating in the inactivation of microorganisms were evaluated by optical emission spectroscopy and Fourier transform infrared spectroscopy. Inactivation curves were fitted to the Bigelow log-linear, the biphasic, and Geeraerd models. According to the results, all plasma treatments inactivated tested microorganisms, depending on a working gas. The most sensitivity of bacteria was observed to the ambient air plasma. Inactivation up to 5 log for E. coli and S. Enteritidis could be achieved within 15 s of plasma treatment. Air plasma exposure of 25 s also led to log10 CFU/ml of B. subtilis from 7.98 to 4.39. S. Enteritidis was slight resistance to plasma treatment with N2. Within 180 s nitrogen plasma treatment, a 2.04 log10 CFU/ml reduction was recorded.