## 2 Results and Discussion
### Phenolic Compounds
#### 2.3.2 Anthocyanins and Color Attributes  
The freeze concentration treatment showed a similar anthocyanin profile as the control (Table 5). Regarding their structures, these anthocyanins can be grouped into four categories: non-acetylated anthocyanins, acetylated anthocyanins, pyranoanthocyanins, and polymeric anthocyanins. Both of the wines had non-acetylated anthocyanins as their predominant anthocyanins, followed by the acetylated anthocyanins, pyranoanthocyanins, and then polymeric anthocyanins. After fermentation, the treated wine contained a higher content of total anthocyanins, because of a significant content increase in the non-acetylated anthocyanins and the pyranoanthocyanins. This might be due to a concentration effect induced by the freeze concentration application to the grape must before fermentation. In addition, higher alcoholic strength in the treated wine might facilitate the extraction of anthocyanins during fermentation [52, 53, 54]. In our study, the pyranoanthocyanin content in the treated wine was about two times higher than that in the control. Pyranoanthocyanins have been reported to possess a more stable structure and have the capacity of enhancing the wine color by shifting wine color from red-purple to a more orange color [55]. Aging the wines for one-year significantly caused the content decrease of anthocyanins in these wines (Table 5), consistent with previous studies [42, 56]. However, the treated wine still showed a higher content. Cold soak maceration application has also been reported to increase the content of anthocyanins in wine after fermentation. However, aging these wines for three months caused a dramatic decrease in the anthocyanin content, leading to a similar content as control [48]. Therefore, the freeze concentration treatment might be a better approach to stabilize anthocyanins in wine during aging. It was also noticed that aging resulted  
\begin{table}
\begin{tabular}{l c c c c} \hline \hline \multirow{2}{*}{**Antheocyanin**} & \multirow{2}{*}{**Quant \({}^{\ast}\)**} & \multicolumn{2}{c}{**Femmentation**} & \multicolumn{2}{c}{**One-Year Aging**} \\ \cline{3-5}  & & **Control** & **Freeze** & **Control** & **Freeze** \\ \hline Non-_ayalted_ anthocyanins & & & & \\ Dephimidin-3-5-O-diglucoside & I & \(1.15\pm 0.09\) c & \(1.78\pm 0.11\) a & \(1.18\pm 0.13\) c & \(1.  
in a content percentage increase in the non-acetylated anthocyanins (from 65% to 74% approx. ), but a decrease in the content percentage of the acetylated anthocyanins in the wines (from 31% to 25% approx.). Meanwhile, the percentage of the detected pyranoanthocyanins in the wine also decreased (from 4% to 2% approx.). These were not consistent with a previous report in which the pyranoanthocyanin content percentage increased after a 2-year aging period [42]. Further investigation should be carried out. A significant difference in the color attributes was observed between the treated wine and the control after the fermentation process (Table 6). For example, the treated wine showed a lower value of L*, b*, and H, but a higher value of a* and C* compared with the control. This indicated that the freeze concentration treatment enhanced the red hue, and reduced the yellow hue of the wine. The enhancement of the red hue in the treated wine might be probably due to the higher amounts of anthocyanins [1; 42], especially the non-acylated anthocyanins. The lightness was reduced after the freeze concentration treatment, whereas the chroma was improved. Aging the wines for one year significantly increased the value of b* and H (Table 6), indicating that these wines turned to be more yellowish in hue and their tone was much greater. The treated wine after one-year aging showed similar values of L*, a*, and C* to the control. However, its b* and H values were lower than the control, indicating that the control showed a more yellowish hue and greater tone than the treated wine.