## 3 Results
### Optimization of Parameters and Design Verification for UV and US Pasteurization  
The optimum condition for UV treatment combined with temperature and flow rate were 2 lamps UV, 50 \({}^{\circ}\)C and 1.5 L/min, respectively. As for the US treatment, the optimum condition was 50 \({}^{\circ}\)C for temperature, 15 min for treatment time, and US power-on position. After determining the optimum condition for UV and US treatment, these two processes were combined and the PJ was examined in terms of the results of TPC, turbidity, \({}^{\circ}\)Brix, and color a*, and yeast and mold count. In consideration of stand-alone optimum conditions, the experimental design for the UV+US process was generated to obtain the optimum combined condition. On the other hand, when the experimental design for the UV+US combined process was carried out with 2 lamps, and 1.5 L/min UV application, the responses obtained from yeast and mold count was not meaningful to find the optimum UV+US combined method condition. For this reason, the flow rate was increased to 3.5 L/min and the number of lamps was decreased to 1 lamp considering the responses obtained from the experimental design. In this way, the condition for flow rate and the number of lamp were modified. Under these circumstances, the optimum condition for UV+US was also carried out at different experimental points and evaluated by an expert design program.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Source** & **Sum of Squares** & **Mean of Square** & **F Value** & \(p\)**-Value** \\ \hline Model & 15.12 & 1.89 & 7.55 & 0.003 \\ X\({}_{1}\) & 5.07 & 5.07 & 20.24 & 0.0015 \\ X\({}_{2}\) & 1.84 & 1.84 & 7.35 & 0.024 \\ X\({}_{3}\) & 3.21 & 3.21 & 12.81 & 0.0059 \\ X\({}_{1}\)X\({}_{2}\) & 0.91 & 0.91 & 3.64 & 0.0889 \\ X\({}_{1}\)X\({}_{3}\) & 2.61 & 2.61 & 10.43 & 0.103 \\ X\({}_{2}\)X\({}_{3}\) & 1.14 & 1.14 & 4.55 & 0.0616 \\ X\({}_{1}\)\({}^{2}\) & 0.071 & 0.071 & 0.28 & 0.6071 \\ X\({}_{2}\)\({}^{2}\) & 0.27 & 0.27 & 1.07 & 0.3289 \\ Residual & 2.25 & 0.25 & & \\ Correction Total & 17.38 & & & \\ R\({}^{2}\)=0.8703 & & & & \\ \hline \hline \end{tabular} \(X_{1}\) (Temperature, \({}^{\circ}\)C), \(X_{2}\) (min), \(X_{3}\) (Ultrasound power on/off), \(p<0.05\) indicates statistical significance ANOVA refers to microbial analysis.  
\end{table}
Table 5: ANOVA analysis results of Central Composite Design (CCD) for yeast and mold count in US pasteurization process (log CFU/mL).  
The results of the study conducted under these conditions can be observed from the values given in Table 6.  
Combined US+UV application at 40 \({}^{\circ}\)C was ineffective on the reduction of yeast and mold count. The application of 50 \({}^{\circ}\)C, and 10 min treatment time reduced the count of yeast and mold to an undetectable level. By applying these conditions, microbial growth was inhibited at lower temperature and treatment time compared with the conventional pasteurization method, and the TPC of PJ was also mostly preserved. Depending on increasing temperature and treatment time, TPC amount of PJ samples significantly increased (\(p<0.05\)). Color a* and turbidity values of PJ samples remained almost the same at the different experimental points (\(p>0.05\)). As for \({}^{\circ}\)Brix results, increasing temperature and treatment time enhanced the \({}^{\circ}\)Brix values of PJ samples (\(p<0.05\)). In a conclusion, the optimum condition for UV+US combined process was the application of the temperature at 50 \({}^{\circ}\)C, UV 1 lamp on, and flow rate 3.5 L/min for 10 min in the US on mode.