## 3 Results and Discussion
### Evaluation of Volatile Aroma Compounds
#### 3.1.1 Monoterpense  
Among young wines, TM7-Y had the highest monoterpene concentrations (Table 1). Aging generally reduced monoterpene levels, except in TM21-A wines, which showed an  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multicolumn{1}{c}{**Volatile Compounds**} & \multicolumn{2}{c}{**Young/Aged**} & \multicolumn{4}{c}{**Treatments**} \\ \cline{3-6}  & **Tm7** & **TM10** & **TM21** & **TPHT** \\ \hline Other esters & & & & & \\ Ethyl lactate & Y & 142,057 \(\pm\) 2847 b  & 137,925 \(\pm\) 6529 b  & 162,549 \(\pm\) 10,898 a  & 55,354 \(\pm\) 6695 c  \\ Ethyl lactate & A & 153,191 \(\pm\) 2942 b  & 171,138 \(\pm\) 5786 b  & 235,716 \(\pm\) 26,846 a  & 131,284 \(\pm\) 6124 c  \\ Diethyl succinate & Y & 8079 \(\pm\) 397 a  & 7363 \(\pm\) 238 b  & 2265 \(\pm\) 186 d  & 2773 \(\pm\) 151 c  \\  & A & 11,982 \(\pm\) 536 b  & 9060 \(\pm\) 593 c  & 17,668 \(\pm\) 1157 a  & 6882 \(\pm\) 461 d  \\ Total other esters & Y & 150,136 \(\pm\) 2574 b  & 145,288 \(\pm\) 6434 b  & 164,815 \(\pm\) 11,083 a  & 58,127 \(\pm\) 6646 c  \\ Volatile phenols & A & 165,173 \(\pm\) 3473 b  & 180,198 \(\pm\) 5298 b  & 253,384 \(\pm\) 26,412 a  & 138,166 \(\pm\) 5687 c  \\ Guaiacol & Y & n.d. & n.d. & n.d. & n.d. \\ Guaiacol & A & 2.28 \(\pm\) 0.34 b  & 2.20 \(\pm\) 0.25 c  & 3.82 \(\pm\) 0.58 a  & 3.03 \(\pm\) 0.36 b  \\ Eugenol & Y & n.d. & n.d. & n.d. & n.d. \\  & A & 3.66 \(\pm\) 0.21 b  & 6.47 \(\pm\) 2.42 b  & 19.73 \(\pm\) 8.04 a  & 2.03 \(\pm\) 109 b  \\
4-Ethylguaiacol & Y & n.d. & n.d. & n.d. & n.d. \\  & A & 531.4 \(\pm\) 342.2 a  & 345.8 \(\pm\) 29.3 b  & 233.3 \(\pm\) 29.5 c  & 326.7 \(\pm\) 56.3 b  \\
4-Ethylphenol & Y & 17.77 \(\pm\) 1.54 a  & 7.79 \(\pm\) 0.23 b  & 1.78 \(\pm\) 0.32 c  & 2.93 \(\pm\) 0.64 c  \\  & A & 352.7 \(\pm\) 6 a  & 376.6 \(\pm\) 27.8 a  & 75.55 \(\pm\) 8.16 b  & 356.2 \(\pm\) 49.6 a  \\  & Y & 24.82 \(\pm\) 0.96 b  & 19.91 \(\pm\) 1.13 c  & 28.25 \(\pm\) 1.95 a  & 23.59 \(\pm\) 1.67 b  \\  & A & 25.44 \(\pm\) 0.98 b  & 23.32 \(\pm\) 1.24 b  & 41.29 \(\pm\) 4.88 a  & 21.30 \(\pm\) 3.70 b  \\ Total volatile phenols & Y & 42.59 \(\pm\) 2.40 a  & 27.70 \(\pm\) 1.25 b  & 30.02 \(\pm\) 2.12 b  & 26.52 \(\pm\) 2.07 b  \\  & A & 915.5 \(\pm\) 29.1 a  & 754.4 \(\pm\) 59.9 b  & 373.7 \(\pm\) 49.3 c  & 709.2 \(\pm\) 110.1 b  \\ Benzenoids & Y & 2.58 \(\pm\) 0.30 & 2.49 \(\pm\) 0.19 & 2.18 \(\pm\) 0.05 & 2.97 \(\pm\) 0.1 \\ Benzaldehyde & A & 2.32 \(\pm\) 0.24 b  & 2.23 \(\pm\) 0.14 b  & 2.89 \(\pm\) 0.36 b  & 7.02 \(\pm\) 0.65 a  \\ Furans & A & 83.84 \(\pm\) 4.21 a  & 81.83 \(\pm\) 7.07 a  & 91.05 \(\pm\) 8.03 a  & 59.03 \(\pm\) 6.58 b  \\ Total furans & Yincrease and the highest post-aging concentrations. Monoterpene changes involve acid and enzyme-catalyzed hydrolysis, isomerization, and cyclization [27], along with yeast activity during maceration and fermentation. Their concentrations are influenced by skin extraction [28], hydrolysis of bound forms, yeast conversion, and adsorption by solids [29]. Grape skins, which contain more free and glycosylated monoterpenes than the flesh/juice [10], are typically favored for extraction. In this study, TM21-Y wines showed lower monoterpene concentrations compared to control TM7-Y, possibly due to the losses during fermentation and extended maceration, attributed to adsorption onto yeast and solids, followed by precipitation. In previous research, high negative correlations were found between linalool, nerol, citronello, and geraniol concentrations, and the duration of maturation in macerated wines [30]. The pre-fermentation heating treatment TPHT-Y also significantly reduced monoterpene concentrations, which was consistent with previous findings on their thermal degradation at 70 \({}^{\circ}\)C for 3 h [31]. Significant changes in monoterpenes also occur during aging [8], where the cleavage of glycosidic bonds can increase and oxidation can decrease their concentration.