## 3 Results  
### Inactivation Effect of IPL Treatment on Seeds and Powdered Foods  
The changes observed in the total microorganisms after treating the four sample types using the developed pilot-scale IPL device are shown in Figure 3.  
Sesame seed samples showed the greatest inactivation, with a 3.07-log reduction, while ground black pepper, ground red pepper, and embryo buds of rice showed 0.45-, 0.66-, and 0.88-log reductions, respectively. The maximum reduction effect varied with the sample type, but the tendency for the inactivation level to improve with increasing treatment time and lamp voltage was the same for all four samples. Since only relatively small reductions have been reported in the literature for powdered foods, many experiments have employed thermal sterilization methods [14; 15; 16]. There are some studies on non-heating treatment using UV-C. Of course, the effect of reducing microorganisms was significantly low despite the large amount of energy used. [PERSON] et al. [14] observed that the reduction in microorganisms on powdered red pepper after exposure to UV-C light at 20.4 kJ/m\({}^{2}\) was 0.22-0.29 log CFU/g. [PERSON] et al. [17] achieved a 2-log reduction of microorganisms on aspberries when applying UV-C light at 11.9 kJ/m\({}^{2}\). However, many previous studies did not investigate temperature increases. [PERSON] and [PERSON] [18] studied the inactivation effects of pulsed UV light against two types of bacteria (_E. coli_ O157:H7 and _Listeria monocytogenes_) inoculated on raw salmon-filtel skin and muscle for various treatment times and distances between a UV light stroke and samples. In all treatments, the temperature of the salmon filter increased to 100 \({}^{\circ}\)C. Similarly, [PERSON] et al. [19] observed temperature increases to 120 \({}^{\circ}\)C when measuring the inactivation effect of pulsed UV light against _Aspergillus niger_ inoculated on cornmeal. Since the above two studies involved laboratory-scale experiments using small samples, they did not monitor for extreme temperature increases. However, adding an efficient cooling system and setting a limit for any temperature increase should be considered when using a pilot-scale device for food-industry applications, since otherwise, it is difficult to distinguish whether microbial inactivation is due to the thermal effect or the direct effects of IPL.  
In contrast, the IPL device used in the present study reduced microorganisms on sesame seeds by more than 3-log CFU/g when applying a total fluence of only 11.26 J/cm\({}^{2}\). In addition, the temperature of the samples did not exceed 3.1 \({}^{\circ}\)C during the IPL treatment due to the chilling system mentioned above. Since there are no studies that have achieved more than 3-log microbial reduction effects by processing a large amount of powdery food, the IPL device used in this study showed the high possibility for application in the food industry as a nonthermal processing technology. However, the changes for ground  
Figure 3: Microbial inactivation effects after IPL treatment of sesame seeds, ground black pepper, ground red pepper, and embryo buds of rice. Data are mean and SEM values.  
black pepper, ground red pepper, and embryo buds of rice did not exceed 1-log reductions, with the effect being slightly better for ground red pepper and embryo buds of rice than for ground black pepper. These results are explained below from both macroscopic and microscopic viewpoints.