Surface disinfection of eggshells with a nanotechnology-based approach

Surface disinfection of eggshells with the use of a novel low-cost, chemical-free, non-thermal, nanotechnology-based approach while preserving quality. 

The safety of hen eggs is essential to reducing the risk of foodborne illness for consumers, as they play a significant role in the human diet. Salmonella typhimurium (S. typhi), Escherichia coli (E. coli), Alcaligenes spp., Bacillus spp., Pseudomonas spp., Proteus spp., and Listeria monocytogenes are just a few of the pathogens that can be found in eggs (1). These microorganisms can contaminate eggs during production, processing, preparation, and packaging (2;3). To protect public health and stop the spread of foodborne illnesses, it is crucial to address the food safety hazards connected to the hen egg lifecycle, from farm to table. 

Eggs are frequently cleaned in hot water containing sanitisers before being processed commercially in several nations (4; 5). The pathogenic microbe load on the eggshell surface can be decreased by 1 to 6 log units (6) by washing the eggs. Nonetheless, it was shown that 8.3% of cleaned eggs were still contaminated with Salmonella spp (7). Chemical residues on eggshells and possible harm to the cuticle, a natural physical barrier shielding the contents of eggs from invasive organisms, are side effects of washing (8; 9; 10). Environmental issues associated with the egg-washing process include the use of a lot of water and the production of a significant volume of waste that is chemically polluted (11; 12). 

Another method used in industry is decontaminating egg surfaces with hot air. This method is quick, easy, and effective in inactivating microorganisms, but it can also result in eggshell cracking, denaturation of proteins, and the formation of gel networks (13; 14; 5). Because of the stated drawbacks associated with thermal treatment techniques and egg surface washing, the introduction of chemical-free and non-thermal approaches could be advantageous for egg production industries (11; 15). Currently, alternative methods that have been reported include ozone, irradiation, UV light, pulsed light, electrolysed water, and non-thermal atmospheric plasma treatments. These methods achieve microbial inactivation, but they are dependent on dosage/level, and pH sensitivity.

Engineered Water Nanostructures (EWNS) are a unique antibacterial platform that is low-cost, chemical-free, and based on nanotechnology. It has recently been introduced for use in the food industry. This approach depends on combining electrospraying and ionising to produce EWNS (18; 19). The spray liquid (water) is aerosolised by creating a strong electric field between a counter electrode and a metal capillary. At the same time, some water and air molecules, particularly oxygen, split and lose electrons (ionisation) due to the high electric field, and consequently a large number of reactive oxygen species (ROS), primarily hydroxyl and superoxide radicals are formed. The concurrently generated ROS, with a nanosecond’s lifespan, is embedded in the droplets, which are responsible for EWNS oxidising and biocidal properties (20; 18; 21). Figure 1 depicts the device’s schematic for producing the EWNS. The system includes an egg holder, syringe pumps, counter electrode, high voltage power source, and enough emitters/injectors (16 total) to cover half of an egg with the EWNS.

Figure 1. The device’s schematic for producing the EWNS (22).

According to the results of Zhang, L., et al., 2024, an effective reduction of  Escherichia coli (E. coli) and Salmonella can be achieved by treating the egg surface with the nano-sized droplets generated through electrospray. After five minutes of exposure time using the EWNS approach, an electric field intensity of 9.0 kV/cm and a water flow rate of 1 μL/min/needle resulted in an 80.4% and 97.6% inactivation efficiency for E. coli and Salmonella, respectively. Furthermore, the physical, chemical, and eggshell cuticle coverage of the treated eggs did not differ significantly from those of the control (unwashed) eggs, indicating that the EWNS treatment had no negative effects on the egg quality metrics that were assessed (22). 

References

1. Widyastuti, E., Mashitoh, D., & Yunianta. (2019). Optimization of high voltage sterilization machine based on dielectric barrier discharge plasma against salmonella sp. with response surface methodology on (gallus domesticus) chicken egg. In IOP conference series: Earth and environmental science (Vol. 230). https://doi.org/10.1088/1755-1315/230/1/012002    
2. Tayel, A. A., El-Sedfy, M. A., Ibrahim, A. I., & Moussa, S. H. (2018). Application of Quercus infectoria extract as a natural antimicrobial agent for chicken egg decontamination. Revista Argentina de Microbiología, 50(4), 391–397. https://doi.org/10.1016/j.ram.2017.12.003 
3. Grande Burgos, M. J., Férnandez Marquez, M. L., Pérez Pulido, R., Galvez, A., & Lucas Loez, R. (2016). Virulence factors and antimicrobial resistance in Escherichia coli strains isolated from hen eggshells. International Journal of Food Microbiology, 238, 89–95. https://doi.org/10.1016/j.ijfoodmicro.2016.08.037 
4. Stolz, N., Weihe, T., Stachowiak, J., Braun, P., Schluter, O., & Ehlbeck, J. (2015). Decontamination of shell eggs by using non-thermal atmospheric pressure plasma. In 15th international conference on biomedical engineering and technology (Vol. 81, pp. 81–84)
5. Lasagabaster, A., Arboleya, J. C., & de Marañón, I. M. (2011). Pulsed light technology for surface decontamination of eggs: Impact on salmonella inactivation and Egg Quality. Innovative Food Science & Emerging Technologies, 12(2), 124–128. https://doi.org/10.1016/j.ifset.2011.01.007 
6. Hierro, E., Manzano, S., Ordóñez, J. A., de la Hoz, L., & Fernàndez, M. (2009). Inactivation of salmonella enterica serovar enteritidis on Shell Eggs by pulsed light technology. International Journal of Food Microbiology, 135(2), 125–130. https://doi.org/10.1016/j.ijfoodmicro.2009.07.034
7. Musgrove, M. T., Jones, D. R., Northcutt, J. K., Harrison, M. A., Cox, N. A., Ingram, K. D., & Hinton, A. J. (2005). Recovery of salmonella from commercial shell eggs by shell rinse and Shell Crush Methodologies. Poultry Science, 84(12), 1955–1958. https://doi.org/10.1093/ps/84.12.1955 
8. Dasan, B. G., Yildirim, T., & Boyaci, I. H. (2018). Surface decontamination of eggshells by using non-thermal atmospheric plasma. International Journal of Food Microbiology, 266, 267–273. https://doi.org/10.1016/j.ijfoodmicro.2017.12.021 
9. Holck, A. L., Liland, K. H., Drømtorp, S. M., Carlehög, M., & McLeod, A. (2018). Comparison of UV-C and pulsed UV light treatments for reduction of salmonella, listeria monocytogenes, and enterohemorrhagic Escherichia coli on eggs. Journal of Food Protection, 81(1), 6–16. https://doi.org/10.4315/0362-028x.jfp-17-128 
10. Medina-Gudiño, J., Rivera-Garcia, A., Santos-Ferro, L., Ramirez-Orejel, J. C., Agredano-Moreno, L. T., Jimenez-Garcia, L. F., Paez-Esquiliano, D., Martinez-Vidal, S., Andrade-Esquivel, E., & Cano-Buendia, J. A. (2020). Analysis of neutral electrolyzed water anti-bacterial activity on contaminated eggshells with salmonella enterica or Escherichia coli. International Journal of Food Microbiology, 320, Article 108538. https://doi.org/10.1016/j.ijfoodmicro.2020.108538 
11. Gavahian, M., Peng, H.-J., & Chu, Y.-H. (2019). Efficacy of cold plasma in producing salmonella-free duck eggs: Effects on physical characteristics, lipid oxidation, and fatty acid profile. Journal of Food Science and Technology, 56(12), 5271–5281. https://doi.org/10.1007/s13197-019-03996-z 
12. Coutinho, N. M., Silveira, M. R., Rocha, R. S., Moraes, J., Ferreira, M. V., Pimentel, T. C., Freitas, M. Q., Silva, M. C., Raices, R. S. L., Ranadheera, C. S., Borges, F. O., Mathias, S. P., Fernandes, F. A. N., Rodrigues, S., & Cruz, A. G. (2018). Cold plasma processing of milk and dairy products. Trends in Food Science & Technology, 74, 56–68. https://doi.org/10.1016/j.tifs.2018.02.008 
13. Keerthirathne, T., Ross, K., Fallowfield, H., & Whiley, H. (2017). Reducing risk of salmonellosis through egg decontamination processes. International Journal of Environmental Research and Public Health, 14(3), 335. https://doi.org/10.3390/ijerph14030335 
14. Berardinelli, A., Cevoli, C., Fabbri, A., Guerzoni, M. E., Manfreda, G., Pasquali, F., Ragni, L., & Vannini, L. (2011). Alternative egg decontamination techniques to washing. Improving the Safety and Quality of Eggs and Egg Products, 181–198. https://doi.org/10.1533/9780857093929.2.181 
15. Dobeic, M., Vadnjal, S., Bajc, Z., Umek, P., Pintarič, Š., Uranjek, I., & Gačnik, K. Š.  (2016). Antibacterial properties of a non-thermal, atmospheric, Openair®, plasma jet in surface decontamination of eggs in shell. Slovenian Veterinary Research, 53(1), 29–41.
16. Indiarto, R., Pratama, A. W., Sari, T. I., & Theodora, H. C. (2020). Food irradiation technology: A review of the uses and their capabilities. International Journal of Engineering Trends and Technology, 68(12), 91–98. https://doi.org/10.14445/22315381/ijett-v68i12p216 
17. Galis¸, A. M., Marcq, C., Marlier, D., Portetelle, D., Van, I., Beckers, Y., & Théwis, A. (2013). Control of salmonella contamination of shell eggs-preharvest and postharvest methods: A review. Comprehensive Reviews in Food Science and Food Safety, 12(2), 155–182. https://doi.org/10.1111/1541-4337.12007 
18. Si, J., Kirychuk, S., Yang, Y., Martel, M., Thompson, B., Zhang, L., Predicala, B., & Guo, H. (2022). Research note: Evaluation of the efficacy of engineered water nanostructures in inactivating airborne bacteria in poultry houses. Poultry Science, 101(2), Article 101580. https://doi.org/10.1016/j.psj.2021.101580 
19. Yang, Y., Martel, M. C., Thompson, B. N., Guo, H., Predicala, B. Z., Zhang, L., & Kirychuk, S. P. (2021). Characterisation of engineered water nanostructures (EWNS) and evaluation of their efficacy in inactivating Escherichia coli at conditions relevant to livestock operations. Biosystems Engineering, 212, 431–441. https://doi.org/10.1016/j.biosystemseng.2021.11.003 
20. Huang, R., Vaze, N., Soorneedi, A., Moore, M. D., Xue, Y., Bello, D., & Demokritou, P. (2019). Inactivation of hand hygiene-related pathogens using engineered water nanostructures. ACS Sustainable Chemistry & Engineering, 7(24), 19761–19769. https://doi.org/10.1021/acssuschemeng.9b05057 
21. Vaze, N., Pyrgiotakis, G., McDevitt, J., Mena, L., Melo, A., Bedugnis, A., Kobzik, L., Eleftheriadou, M., & Demokritou, P. (2019). Inactivation of common hospital acquired pathogens on surfaces and in air utilizing engineered water nanostructures (EWNS) based nano-sanitizers. Nanomedicine: Nanotechnology, Biology and Medicine, 18, 234–242. https://doi.org/10.1016/j.nano.2019.03.003 
22. Aminian, S., Heydari, M. M., Thompson, B., Schwean-Lardner, K. Kirychuk, S.,
23. Zhang, L. (2024). Application of novel engineered water nanostructures techniques for eggshell surface decontamination. LWT 200 (2024) 116151. https://doi.org/10.1016/j.lwt.2024.116151