## Results and Discussion
### Total Phenols, Total Flavonoids, Total Anthocyanins, and Color Attributes  
Phenolic compounds in wine can be divided into anthocyanins and non-anthocyanin phenolic compounds regarding their contribution to wine sensory quality [27]. Anthocyanins are the most important colorants in wine and play important roles in the appearance of wine, whereas non-anthocyanin phenolic compounds are mainly responsible for the mouthfeel and palatability of wine [18]. Non-anthocyanin phenolic compounds, based on their chemical structures, can be further classified into flavanols, flavonoids, and phenolic acids. Table 2 lists the content of the total anthocyanins, total flavonoids, and total phenols of these bog bilberry syrup wines supplemented with different amounts of DAP. No significant effect on the content of the total anthocyanins was found among these different DAP-supplemented bog bilberry syrup wines. However, a significant increase in the level of the total flavonoids and total phenols were observed in these wines with the increase of the DAP supplement amount. For example, the concentration of the total flavonoids in the wine significantly increased from 12.88 mg/L to 14.72 mg/L with the DAP supplement amount from 60 mg/L to 150 mg/L. The wine supplemented with 150 mg/L DAP displayed higher content of the total phenols (892.27 mg/L) compared to the wine with 60 mg/L DAP (749.72 mg/L). It has been shown that oxidation occurs during the wine fermentation process, resulting in the decrease of phenolic compound content [28]. The DAP supplementation in the present study, however, significantly reduced the bog bilberry syrup wine fermentation period, which might prevent phenolic compounds from oxidation since a higher phenolic compound degradation has been reported to be found in a longer fermentation period [29]. Higher content of phenols in wine has been reported to improve the volatility of odorants, which might enhance the release of volatiles from wine and increase the wine sensory perception [30] In addition, non-anthocyanin phenolic compounds have been reported to play important roles in stabilizing anthocyanins during wine fermentation by interacting with anthocyanins via co-pigmentation and polymerization [31]. No significant alteration of the total anthocyanin content \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Physicochemical Index**} & \multicolumn{4}{c}{**Wine with Dibasic Ammonium Phosphate (mg/L) a**} \\ \cline{2-5}  & **60** & **90** & **120** & **150** \\ \hline Fermentation Period (days) & 19 & 17 & 14 & 14 \\ Alcohol (\%, vol) & 9.1 \(\pm\) 0.2 a & 9.8 \(\pm\) 0.1 b & 10.6 \(\pm\) 0.2 c & 11.0 \(\pm\) 0.1 d \\ Total Sugar (g/L) & 18.84 \(\pm\) 0.11 c & 10.11 \(\pm\) 0.43 b & 10.10 \(\pm\) 0.17 b & 8.32 \(\pm\) 0.31 a \\ Reducing Sugar (g/L) & 16.07 \(\pm\) 0.39 c & 7.25 \(\pm\) 0.54 b & 7.22 \(\pm\) 0.03 b & 5.84 \(\pm\) 0.32 a \\ pH & 3.14 \(\pm\) 0.01 a & 3.14 \(\pm\) 0.01 a & 3.14 \(\pm\) 0.01 a & 3.14 \(\pm\) 0.01 a \\ Total Acidity (g/L) & 8.47 \(\pm\) 0.17 a & 8.66 \(\pm\) 0.21 a & 8.56 \(\pm\) 0.02 a & 8.71 \(\pm\) 0.07 a \\ \hline \hline \end{tabular}  
* Data are the mean \(\pm\) standard deviation of triplicate tests. Different letters in each row indicate significant differences at \(p\leq\) 0.05.  
\end{table} 
Table 1: Physicochemical indexes of bog bilberry syrup wine supplemented with different amounts of dibasic ammonium phosphate (DAP). was observed in these wines supplemented with different DAP supplement amounts, indicating that the level of phenolic compounds in these wines might be sufficient for the stabilization of anthocyanins. Regarding the CIELab assay, a* represents the redness/greenness of wine, whereas b* indicates the yellowness and blueness. The lightness of wine is determined by the L* value (K