Investigating cold plasma jet effectiveness for eggshell surface decontamination

Ensuring the safety of eggs, a valuable source of high-quality protein and essential vitamins, is critical to prevent foodborne illness. Cold plasma, an emerging green technology, generates various reactive species that effectively inactivate microorganisms, attracting global attention for its potential in food safety. This study aims to explore the application of cold plasma as a chemical-free, non-thermal approach for decontaminating egg surfaces and to assess its potential as an alternative to conventional egg-washing methods. Various operation conditions of a cold plasma jet device, including power levels (300–400 W), exposure times (20–60 s), distances between the nozzle and eggshell (1–3 cm), airflow rates (30–35 L/min), and feed gases (nitrogen, air (20 %–65 % relative humidity), helium and air mixtures), were examined to decontaminate hen eggshells inoculated with Escherichia coli and Salmonella enterica bacteria. The results showed a maximum log reduction and deactivation efficiency of 1.94 and 98.74 % for E. coli, and 1.11 and 92.20 % for Salmonella, after a 60 s treatment of egg surface using a cold plasma device set at 1 cm distance, 400 W power, and 35 L/min airflow with 65 % relative humidity. Moreover, our findings indicated no significant differences in egg quality, eggshell cuticle chemical composition, and cuticle coverage between untreated eggs and those treated with cold plasma. This suggests the potential of this non-chemical, non-thermal emerging technique to be commercialized as a substitute for conventional washing methods.