Changes to Pork Bacterial Counts and Composition After Dielectric Barrier Discharge Plasma Treatment and Storage in Modified-Atmosphere Packaging

The aim of this study was to compare the succession of natural microbiota in pork held under refrigerated storage for up to 10 days after dielectric barrier discharge (DBD) plasma treatment. Two methods were used to assess the impact of DBD on microorganisms. Firstly, traditional selective media (SM) were employed to detect the bactericidal effects of DBD on <i>Pseudomonas</i> spp., <i>Enterobacteriaceae</i>, <i>Lactic acid bacteria</i> (LAB), and <i>Brochothrix thermosphacta</i>. Secondly, the thin agar layer (TAL) method was used to further evaluate the bactericidal effects of DBD. In addition, the Baranyi and Roberts model was applied to explore the kinetic parameters of <i>Pseudomonas</i> spp., <i>Enterobacteriaceae</i>, LAB, and <i>B. thermosphacta</i> during storage. Finally, the modified Lotka-Volterra model was used to describe the interactions between each microorganism. The study found that when using traditional selective media (SM), 85 kV DBD had a significant bactericidal effect on <i>Pseudomonas</i> spp., <i>Enterobacteriaceae</i>, LAB, and <i>Brochothrix thermosphacta</i>. However, when using the thin agar layer (TAL) method, the results suggested that DBD had no significant bactericidal effect, suggesting that DBD caused sublethal damage to the natural microorganisms on pork. Analysis with the Baranyi and Roberts model showed that DBD treatment significantly extended the lag phase of these four types of microorganisms and significantly reduced the μ_max of all microorganisms except LAB. The analysis results of the modified Lotka-Volterra model showed that LAB had a greater impact on <i>Pseudomonas</i> spp., <i>Enterobacteriaceae</i>, and <i>B. thermosphacta</i> (a₂₁ > a₁₂). In conclusion, DBD treatment was shown to have a significant sublethal bactericidal effect that impacted both the count and composition of natural microorganisms found on pork.