## 4 Discussion  
This study developed a sterilization device for seeds and powdered foods based on IPL and consisting of two power supplies, two xenon lamps, and a treatment chamber. The device was designed to allow samples to receive as much light as possible for as long as possible in order to increase its effectiveness. The sample flows through the device in a cyclonic manner, which allows the sample to remain in the chamber for longer than if it simply fell straight through and also is less likely to be present in clumps. Each of the two power supplies was set at 1800-4200 V for 1-5 min in the experiments performed in this study. The resulting microbial inactivation effects for sesame seeds, embryo buds of rice, ground red pepper, and ground black pepper decreased in the order of 3.07-, 0.88-, 0.66-, and 0.45-log reductions, respectively. These results can be explained by considering both macroscopic and microscopic differences between the samples. First, from a macroscopic viewpoint, the morphologies of sample surfaces vary depending on whether or not they have been ground, and the presence of irregular cracks would result in shadow effects and associated reductions in microbial inactivation. Additionally, the inactivation effect will be lower for darker samples due to less absorption of the incident UV light. Second, from a microscopic viewpoint, the natural microflora present differed between the samples. The inactivation effect was lower for samples harboring low-susceptibility spores since they are more resistant than vegetative cells and molds. In addition to microbiological changes, physical changes that may affect sensory properties are also important to consider. The present statistical analyses revealed that there were no significant changes in color, water activity, or moisture content in the four samples. In conclusion, this study showed that the present pilot-scale IPL device for processing seeds and powdered foods is capable of handling large amounts of samples daily. It is highly significant that no changes were observed in the basic properties of food after IPL because it means that IPL can fully compensate for the disadvantages of heat sterilization. It is expected that this study will contribute to the commercialization of IPL technology, and further studies for developing a device that combines other nonthermal techniques for applying to spices, other seeds, and powdered foods contaminated by microorganisms need to be conducted. Conceptualization, H.-J.H. and S.-Y.Y; methodology, S.-Y.Y. ; software, S.-Y.Y. ; validation, H.-J.H. and S.-Y.Y. ; formal analysis, S.-Y.Y. ; investigation, S.-Y.Y. ; resources, S.-Y.Y. ; data curation, H.-J.H. ; writing--original draft preparation, S.-Y.Y. ; writing--review and editing, H.-J.H. ; visualization, H.-J.H. ; supervision, M.-S.C.; project administration, M.-S.C. All authors have read and agreed to the published version of the manuscript. This research received no external funding. Not applicable. The data presented in this study are available on request from the corresponding author. This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2019R1A2C1085100).