## 3 Results and Discussion
### Effects of the UV Light Source and TiO\({}_{2}\) Photocatalysis on Inactivation of Microorganisms
coli_ K12; (**b**) _Saccharomyces cerevisiae._ UVC = UVC (254 nm) photolytic treatment; VUV = VUV (254 nm and 185 nm) photolytic treatment; UVC-TiO\({}_{2}\) = UVC-assisted TiO\({}_{2}\) photocatalytic treatment. The \(N_{0}\) of _E. coli_ K12 and _S. cerevisiae_ were 6.9 and 5.3 log CFU/mL, respectively. All of the treatments were performed under extra aeration. Results represent the mean of three measurements \(\pm\) standard deviation. Removal of Residual Pesticides on Fresh Cut Carrots under Combined UV and Combined UV-TiO\({}_{2}\) Treatments  
Initial concentrations of pyracolostrobin, boscalid, fluidoxonil, and azoxystrobin on carrot samples were approximately 3.5 ppm, 2.9 ppm, 3.4 ppm, and 5.7 ppm, respectively. An air pump that was fitted at the bottom of the reactor helped to create turbulence in the wash water for random rotation of carrots to achieve uniform degradation (Figure 6). This bubble generation system in the wash water also helped with the removal of residual pesticides. After 60 min of bubble water washing, the removal percentages of pyracolostrobin, boscalid, fluidoxonil, and azoxystrobin were 53.0%, 74.2%, 68.5%, and 75.7% of the initial concentrations, respectively. Both combined UV and combined UV-TiO\({}_{2}\) showed removal percentages of approximately 75%, 72%, 83%, and 94%, respectively. Combined UV-TiO\({}_{2}\) did not produce a better photocatalytic removal efficiency than combined UV, similar to the data in Figure 2. No significant variations were observed in a trend of reduction for all measurements. Thus, fresh cut carrots can be a suitable simulation model for pesticide reduction experiments on fresh produce. Figure 6: Removal of residual pesticide contamination from fresh cut carrots using combined UV and combined UV-TiO\({}_{2}\). **(a)** pyracolostrobin; **(b)** boscalid; **(c)** fluidoxonil; and, **(d)** azoxystrobin. Bubble water wash (BW) = air bubbling as a control; Combined UV = UVC and VUV; combined UV-TiO\({}_{2}\) = UVC-assisted TiO\({}_{2}\) photocatalytic; and, VUV-assisted TiO\({}_{2}\) photocatalytic treatment. The \(C_{0}\) of pyracolostrobin, boscalid, fluidoxonil, and azoxystrobin were approximately 3.5, 2.9, 3.4, and 5.7 ppm, respectively. The results represent the mean of three measurements \(\pm\) standard deviation. In this study, the degradation rate of pesticides was slowed down along the course of the reaction time that can be attributed to the accumulation of oxidation intermediates. This decontamination technique for solid food materials is expected to be improved for a higher degradation rate by applying an open system with a continuous water flow through which clean water can be continuously supplied and treated wash water containing oxidizing intermediates is discharged. Meanwhile, it is necessary to first understand the presence and mutual effects of components that might reduce the reaction efficiency of the entire system, such as azoxystrobin in the present investigation, in order to apply it to the liquid medium of a multi-component system such as surface/ground water. Based on this information, this decontamination technique could be applied to multi-component systems in combination with mechanical means, including high turbulence, positive irradiation structures, and static mixers or bubbles. Inactivation of Microorganisms on Fresh Cut Carrots with Combined UV and Combined UV-TiO\({}_{2}\) Treatments  
Initial populations of _E. coli_ K12 and _S. cerevisiae_ on the carrot surface model were in the range of 6.5-8.0 log CFU/cm\({}^{2}\) and 4.3-5.6 log CFU/cm\({}^{2}\), respectively. The populations of _E. coli_ K12 were reduced by 0.7 log, 1.3 log, and 1.5 log after 60 min of bubble water wash, combined UV, and combined UV-TiO\({}_{2}\) treatments, respectively (Figure 7a). For _S. cerevisiae_, 0.6 log, 1.2 log, and 1.6 log inactivations were achieved by the bubble wash, combined UV, and combined UV-TiO\({}_{2}\), respectively, for 60 min (Figure 7b).