## 3 Results and Discussion
### Color Change and Sensory Evaluation  
The impact of both pasteurization methods on the color change and sensory quality of the juices is depicted in Figures 2 and 3. Microwave pasteurization exhibits a lesser effect on the initial color of the product compared to TP. According to the literature, when the total color difference is less than 1.5, it indicates changes that are imperceptible to the human eye [64]. In our study, this threshold was exceeded by more than four times after MFP and even more significantly after TP, suggesting that both techniques caused significant changes in apple juice color. However, the changes induced by MFP were less visually apparent compared to TP-treated samples. In a study of camu camu juice by [PERSON] et al. (2019) [62], the use of higher power and longer microwave time (900 W, 45 s) resulted in lower changes in \(\Delta E\). The authors attributed this effect to the greater extraction of bioactive compounds, which contributed to maintaining the color at a high level. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**Floridzin (mg/L)**} & \multicolumn{2}{c}{**Epicatechin (mg/L)**} & \multicolumn{2}{c}{**Chlorogenic Acid (mg/L)**} & \multicolumn{2}{c}{**Caffeic Acid (mg/L)**} \\ \hline
**FJ** & **10.29 \(\pm\) 0.15 \({}^{\ast}\)** & \multicolumn{2}{c}{**2.67 \(\pm\) 0.04 \({}^{\ast}\)**} & \multicolumn{2}{c}{**27.89 \(\pm\) 0.05 \({}^{\ast}\)**} & \multicolumn{2}{c}{**0.76 \(\pm\) 0.10 \({}^{\ast}\)**} \\ \hline
**Storage Time** & \multicolumn{2}{c}{**TP**} & **MFP** & **TP** & **MFP** & **TP** & **MFP** & **TP** & **MFP** \\ \hline
0 & 10.67 \(\pm\) 0.22 \({}^{\ast}\) & 10.70 \(\pm\) 0.11 \({}^{\ast}\) & 2.57 \(\pm\) 0.08 \({}^{\ast}\) & 27.47 \(\pm\) 0.18 \({}^{\ast}\) & 27.50 \(\pm\) 0.15 \({}^{\ast}\) & 150.89 \(\pm\) 0.02 \({}^{\ast}\) & 0.81 \(\pm\) 0.02 \({}^{\ast}\) & 0.60 \(\pm\) 0.01 \({}^{\ast}\) \\
2 & 7.01 \(\pm\) 0.12 \({}^{\ast}\) & 7.55 \(\pm\) 0.17 \({}^{\ast}\) & 1.35 \(\pm\) 0.36 \({}^{\ast}\) & 6.42 \(\pm\) 0.28 \({}^{\ast}\) & 22.09 \(\pm\) 0.11 \({}^{\ast}\) & 131.37 \(\pm\) 0.17 \({}^{\ast}\) & \(<\)LOQ & \(<\)LOQ \\
4 & 5.19 \(\pm\) 0.21 \({}^{\ast}\) & 5.44 \(\pm\) 0.05 \({}^{\ast}\) & \(<\)LOQ & 5.61 \(\pm\) 0.14 \({}^{\ast}\) & 21.49 \(\pm\) 0.03 \({}^{\ast}\) & 121.97 \(\pm\) 1.15 \({}^{\ast}\) & \(<\)LOQ & \(<\)LOQ \\
6 & 4.98 \(\pm\) 0.12 \({}^{\ast}\) & 3.43 \(\pm\) 0.08 \({}^{\ast}\) & \(<\)LOQ & \(<\)LOQ & 21.95 \(\pm\) 0.48 \({}^{\ast}\) & 5.46 \(\pm\) 0.03 \({}^{\ast}\) & \(<\)LOQ & \(<\)LOQ \\
8 & 4.48 \(\pm\) 0.05 \({}^{\ast}\) & 3.36 \(\pm\) 0.04 \({}^{\ast}\) & \(<\)LOQ & \(<\)LOQ & 8.51 \(\pm\) 0.32 \({}^{\ast}\) & \(<\)LOQ & \(<\)LOQ & \(<\)LOQ \\ \hline \hline \end{tabular} Mean values marked with the same letters within the parameter do not differ statistically significantly in the same factor, \(p\leq 0.05\).  
\end{table} 
Table 2: Concentration of individual polyphenols in FJ, TP and MFP-preserved apple juices. Figure 2: Changes in total color difference (\(\Delta E\)) in TP and MFP-preserved apple juices. Mean values denoted with the same letters do not differ significantly statistically, \(p\leq 0.05\). Color changes were also observed during sensory evaluation (Figure 3). The storage period of the juice was associated with a decline in its sensory quality, which was reflected in its overall evaluation. Throughout the storage period, the juice treated with MFP consistently received higher scores during sensory evaluation compared to TP-treated juice. [PERSON] et al. (2010) [65] showed that the color change after microwave preservation of orange juice is mainly related to the temperature used rather than the treatment time. These observations suggest that while both pasteurization methods lead to noticeable color changes, MFP appears to have a milder impact on the initial color of the juice when compared to TP.