## 4 Impacts of HTST and UHT on Food Quality
### Bioactive Compounds
#### 4.3.2. Phenolics
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Matrix** & **Parameters** & **Phenolic Compounds** & **Vitamins** & **Other Bioactive Ingredients** & **Reference** \\ \hline \hline \begin{tabular}{c} Acerola juice, acerola juice \\ + inulin, acerola juice + \\ gluco-oligosaccharides \\ \end{tabular} & \(136\) \({}^{\circ}\)C/4.1 s & - & All—vitamin C \(\uparrow\) * & - & [76] \\ \hline \hline \begin{tabular}{c} Mango nectar \\ \end{tabular} & \(110\) \({}^{\circ}\)C/8.6 s & TPC—no statistical difference & Vitamin C—no statistical difference & TCC—no statistical difference & [44] \\ \hline \hline \begin{tabular}{c} Watermelon juice \\ \end{tabular} & \(\begin{tabular}{c} \(110\) \({}^{\circ}\)C/2 s \\ \(120\) \({}^{\circ}\)C/2 s \\ \(135\) \({}^{\circ}\)C/2 s \\ \end{tabular} & \begin{tabular}{c} TPC \(\downarrow\) * at 110 and no statistical \\ difference at 120 and 135 \({}^{\circ}\)C \\ \end{tabular} & - & - & [24] \\ \hline \hline \begin{tabular}{c} Pomegranate juice \\ \end{tabular} & \(110\) \({}^{\circ}\)C/8.6 s & Total monomeric anthocyanins & Vitamin C 40.8\% \(\downarrow\) * & - & [70] \\ \hline \hline \begin{tabular}{c} Orange juice \\ \end{tabular} & \(130\) \({}^{\circ}\)C/2 s & TPC—7.2\% \(\downarrow\) & Vitamin C 7.2\% \(\downarrow\) * & TCC 13.7\% \(\downarrow\) * & [22] \\ \hline \hline \
\begin{tabular}{c} Acai juice \\ \end{tabular} & \(138\) \({}^{\circ}\)C/6 s &
\begin{tabular}{c} TPC \(\downarrow\) * \\ Anthocyanins \(\downarrow\) * \\ \end{tabular} & Vitamin C \(\downarrow\) * & & [51] \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Effect of UHT processing on the contents of selected bioactive compounds. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
As a result of the UHT preservation, a significant decrease of 31.4% in the total phenolic content (TPC) of red raspberry juice was observed by [PERSON] et al. [84]. [PERSON] et al. [87] reported a reduction in the TPC of 10-28% in cloudy apple juices, [PERSON] et al. [38] in cloudy ginger juice of 14.7%, [PERSON] et al. [39] in papaya beverage of 12.7%, [PERSON] et al. [53] in red grapefruit juice of 7.7%, and [PERSON] et al. [54] in korla pear juice of 4.7%. However insignificant changes were noted by [PERSON] et al. [36] in carambda juice. [PERSON] et al. [17], because of UHT preservation of black carrot juice, observed significant decreases in total flavonoid and total anthocyanins contents of 14.2% and 8.6%, respectively. On the other hand, after UHT processing, [PERSON] et al. [12] observed increases in flavonoid and proanthocyanidins contents of 25.5% and 5.6%, respectively. Increases in TPC contents were noted by [PERSON] et al. [35] and [PERSON] et al. [27] after UHT in purple sweet potato nectar and mulberry juice. No significant changes in TPC were observed by [PERSON] et al. [42] in a pepper and orange juice blend and by [PERSON] et al. [44] in mango nectars. The type of food matrix is of great importance. [PERSON] et al. [25] showed that the effect of beverage clarity is relevant. These authors found that in preserved clear, Se-enriched kiwifruit juice, there was a significant decrease in TPC of 5.2%, while in the cloudy version, there was a minimal increase of 0.5%. UHT preservation caused a significant decrease in quercetin content in tomato juice, while there were no significant changes in chlorogenic or caffe acid contents [18]. Researchers confirm that the phenolics contents of preserved samples decreased during storage, which may be related to oxidation degradation [35]. Following preservation at 110 \({}^{\circ}\)C/8.6 s and refrigerated storage for 25 days, the TPC decreased by 90.7% [42]. However, less degradation of phenolics was reported by [PERSON] et al. [44], at about 17.0% and 25.2% at 4 \({}^{\circ}\)C and 25 \({}^{\circ}\)C, respectively. It is emphasized that thermal inactivation of enzymes can also lead to the retention of a significant portion of anthocyanins in a sample immediately after preservation, as well as during storage.