Large-scale spatial atmospheric-pressure Corona discharge characteristics and their disinfection effect on corn kernels

Plasma, as an environmentally friendly processing technology, shows considerable potential for microbial control in grain storage. In this study, a large-scale spatial atmospheric-pressure Corona discharge device was designed to enable single-batch treatment of 25 g of corn kernels under storage-like conditions, and its disinfection performance against Escherichia coli on corn kernel surfaces was systematically investigated. Artificially contaminated corn kernels were used as model samples, and the discharge characteristics under different conditions were examined by varying the container material, the diameter of the high-voltage iron-rod electrode, and the operating distance between the electrode and the corn kernels. Disinfection efficacy was evaluated using both the adenosine triphosphate bioluminescence assay and the dilution plate-counting method. The results indicate that under operating conditions of 18 kV and 20 kHz, a 10 min plasma treatment achieved a maximum inactivation rate of 99.96% for E. coli on corn kernels. The container material, high-voltage electrode diameter, and operating distance exerted significant effects on disinfection efficiency. Plastic containers and fine-rod electrodes exhibited superior disinfection performance during prolonged treatment, whereas the selection of operating distance required a balance between discharge coverage area and discharge intensity. Furthermore, during a 120-day storage period, plasma treatment effectively suppressed corn weevil infestation. Scanning electron microscopy observations revealed a pronounced increase in surface roughness of corn kernels after plasma treatment, accompanied by structural alterations in the matrix surrounding the starch granules. Overall, the large-scale spatial atmospheric-pressure Corona discharge device provides a promising green approach for decontamination and pest control during grain storage.