Effect of treatment by non-thermal plasma jet on the growth
of various food spoilage bacteria in superfluous
Tomislava Vukušić1, Višnja Stulić1*, Anet Režek Jambrak1, S. Milošević2, D. Stanzer1, Z. Herceg1
1University of Zagreb, Faculty of Food Technology and Biotechnology, Pierottijeva 6, 10000 Zagreb, Croatia
2University of Zagreb, Institute of Physics, Bijenička 46, 10000 Zagreb, Croatia
original scientific paper
The efficiency of gas phase plasma at atmospheric pressure by using an electrical discharge in gas argon on the inactivation of microorganisms was examined. The gas phase plasma was applied to suspensions of pure cultures Escherichia coli 3014, Staphylococcus aureus 3048, Salmonella sp. 3064, Listeria monocytogenes ATCC 23074 and Bacillus cereus 30. The experiments were planned and performed according to a statistical experimental design, specifically central composite design, which considered three independent variables: volume (2, 3 and 4 mL), gas flow (0.75, 1 and 1.25 L/min) and treatment time (3, 4 and 5 min). Two studied parameters, volume and treatment time, substantially affected the inactivation. For plasma treatment, the inactivation can be attributed to UV radiation and plasma reactive oxygen species (ROS). It was found that Gram-negative bacteria were more susceptible to the plasma treatment than Gram-positive bacteria, and that the susceptibility of Gram-positive bacteria was remarkably species-dependent. Complete inactivation of Escherichia coli, Salmonella sp., and Listeria monocytogenes was achieved when optimal combination of parameters was applied.
Keywords: gas-phase plasma; atmospheric pressure; food spoilage bacteria; response surface methodology