**5. Conclusions**

In conclusion, a constant urge to meet the consumer expectations of fresh, microbiologically safe food products results in the search for new disinfection methods. The findings of the present study indicate that the most effectiveness treatment was RCI and ozonation at contamination level 103 CFU/mL especially with treatment duration of 60 and 120 min. However, at the higher initial contamination levels of 10<sup>5</sup> and 108, the effectiveness of RCI and ozonation was also high with longer treatment. The addition of poultry manure reduced the effectiveness of both methods each time. Because of RCI effectively eliminates *Salmonella* spp. on the eggshells this technology may be a good candidate for the enhancement of biosecurity at farms and egg processing plants.

**Supplementary Materials:** The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/foods11162452/s1, Table S1: The changes in the number of S. Enteritidis, S. Typhimurim, S. Virchow on eggshells contaminated with bacterial suspension of 103 CFU/mL with or without the addition of poultry manure; Table S2: The changes in the number of S. Enteritidis, S. Typhimurim, S. Virchow on eggshells contaminated with bacterial suspension of 105 CFU/mL with or without the addition of poultry manure; Table S3: The changes in the number of *S. enteritidis*, *S. typhimurim*, *S. virchow* on eggshells contaminated with bacterial suspension of 10<sup>8</sup> CFU/mL with or without the addition of poultry manure.

**Author Contributions:** Conception/design, K.G.-B. and K.S.; formal analysis, K.S., E.G.-K. and S.K.; writing-original draft preparation, K.G.-B., E.W.-Z., J.K.-P., M.W. and N.W.-K.; writing-review and editing, K.G.-B., G.G., M.A. and K.J.S.; visualization, K.S., J.K. and Z.P.; supervision, Z.P., E.W.-Z., J.K., J.B. and A.B.; project administration, K.S. and E.G.-K. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the Nicolaus Copernicus University with funds from the maintenance of the research potential of the Department of Microbiology PDB WF and Article Processing Charge was funded with funds from a contest held by the "Excellent Initiative Research University" program at Nicolaus Copernicus University in Toru ´n.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The data presented in this study are available on request from the corresponding author.

**Conflicts of Interest:** The authors declare no conflict of interest.
