# Exploring Red Wines from the Drama Region: A Chemical, Sensory, and Terroir Insight
## 3 Results and Discussion
### Phenolic Content and Profile of Wines  
Figure 3 shows the variation in the Total Phenolic Index (TPI) among the wines, whereas Table 5 reports the major phenolic compounds quantified in the produced wines, which were measured using LC-MS. The representative chromatogram is reported as Supplementary Figure S1. The TPI measured by recording the absorbance at 280 nm (A\({}_{280\,\mathrm{nm}}\)) represents one of the main oenological quality markers used to monitor the levels of phenol compounds in wines. [PERSON] [PERSON] and [PERSON] (2018) noted the importance of the TPI value as a quality parameter in wine and proposed to assess the total phenolic substances in wine. It is visible that the TPI varies among the locations only in the cases of Cabernet Sauvignon and Agiorgitiko cultivars. With regard to Merlot wines, no significant difference was noted among the locations, even though Me-Ad and Me-Ne vineyards were younger than the rest, and younger vineyards tend to have larger grapes with lower skin-to-pulp ratios, leading to lower concentrations of phenolics [PERSON] and [PERSON] (2018). Nevertheless, wines from the Cabernet Sauvignon cultivar exhibited the highest variation among the locations; wine from the Agora vineyard showed almost double the TPI than the other locations. No significant differences were observed among the TPI values among the two growing years for Cabernet Sauvignon and Agiorgitiko cultivars. Wines from the Merlot cultivar produced in 2023 have higher values than in 2022. Although the TPI is considered a reliable phenolic index, the literature notes that only part of phenolics is detectable at this wavelength Flanzy and Poux (2018). Thus, in addition to the spectroscopic technique approach, different methods involving by LC-MS are nowadays applied to detect and quantify the phenolic profile of wines Flanzy and Poux (2018); Poux (2018). In addition, investigating the phenolics' profile for quality control represents a promising tool for quality and authenticity evaluations for wine Flanzy and Poux (2018). Figure 3: Variation in Total Phenolic Index (A\({}_{280\,\mathrm{nm}}\) index) in wines obtained from the cultivars Merlot, Cabernet Sauvignon, and Agiorgitiko grown in different locations. Means are the results of triplicate measurements. Similar letters above the error bars for the same parameter within the same variety are not significantly different (\(p<0.05\)) by [PERSON]’s multiple range test. Abbreviations: Adriani (Ad), Perichora (Pe), Agora (Ag), Kali Vrisi (Kv), Nevrokopi (Ne), and Mikrohori (Mi). \begin{table}
\begin{tabular}{l l c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Peak**} & \multirow{2}{*}{**Analytic \({}^{\ast}\) (signal)**} & \multicolumn{2}{c}{**Retention**} &  
The major phenolic compounds present in the wines were procyanidin B2, catechin, procyanidin B3, procyanidin B1, epicatechin, and gallic acid. These compounds represent more than 90% of the total phenolics quantified in the wine samples. The total amount of phenolics quantified varies among the locations for Merlot and Agiorgitiko but not for Cabernet Sauvignon. A higher amount of total phenolics among the wine samples studied was observed in the Merlot wines from the Nevrokopi vineyard (529.5 \(\upmu\)g/mL), showing more than twice the amount of each of the Merlot samples. Therefore, the Nevrokopi vineyard (860 m) presented a higher phenolic content in comparison to other vineyards situated at lower elevations (<200 m), possibly due to higher UV-B radiation exposure, which promotes the accumulation of phenolic substances in grape skins, including anthocyanins [26]. According to the previous studies [47], more sunny days throughout the growing season led to the grapes accumulating more phenolic and anthocyanin compounds. However, various studies have demonstrated that the effects of vine water status cannot be separated from those of temperature and sunlight with regard to the phenolics' content.