# Volatile Composition of Fortification Grape Spirit and Port Wine: Where Do We Stand?
## 5 Grape Spirits' and Port Wines' Volatile Components and Their Potential Impact on Aroma Properties
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Compound** & **Aroma Descriptor** & \multicolumn{2}{c}{**Concentration Range in Grape Spirits**} & \multicolumn{2}{c}{**Concentration Range in Port Wine**} \\  & & & **(ug/1)** & & **(ug/1)** & \\ \hline Phenylmethanol & Floral, sweet, disinfectant & [83,84] & 100 & [3] & 85.3–720 & [3,50] \\
2-Phenylethanol & Rose, honey & [83,84,85] & 1150 & [3] & 10.20–56,700 & [3,59,50] \\ Acetaldehyde & Overpipe apple & [84,87] & 31,100–1857,710 & [29,45,46] & 1360–49,000 & [3,94,50] \\
2-Oxopropanol & Pumpst, stinging & [106] & 420–16,340 & [29] & 571–25,400 & [16,27,39] \\ Proposal & Sharp and pungent & [106] & 420–220 & [29,45] & 41–403 & [27] \\
2-Methylproponal & Sharp, pungent & [106] & 0.41–16.6 & [29,45] & 24–1087 & [15,27] \\
2-Methylbutanal & Powerstl, choking & [106] & 0.19–5690 & [29,45] & 17–806 & [15,27] \\
3-Methylbutanal & pungent, apple-like & [106] & 9.07–4140 & [29,45] & 20–2246 & [15,27] \\ Benzaldehyde & Smoke, unity, almond & [8,38]–85 & 20–690 & [3,29] & 0.79–897 & [3,97,93,50,52] \\ Nonmal & Fatty & [106] & 0.21–13.35 & [45] & 12–3.1 & [27] \\
3-Methylbut aquatic & Banana, frauity, sweet & [8,38,35–87] & 434 & [3] & 330–1269 & [3,39,50] \\ Dietfly succinate & Fruily, mepor, yeast & [3,87–87] & 6500 & [3] & 20–18,700 & [3,39,50] \\ Ethyl hexanoate & Fruily, green apple, banana, & [83,83–87] & 827 & [3] & 109–1097 & [3,39,50] \\  & brandy, wine-like & [8,38–86] & 55.4 & [3] & 11.6–1179 & [3,9,50] \\
2-Phenylethyl acetate & Flowery, honey & [8,38–87] & 3210 & [3] & 56–3180 & [3,39,50] \\ Ethyl octanoate & Sweet, floral, fruits, banana, & [8,38–87] & 3210 & [3] & 56–3180 & [3,39,50] \\ Ethyl & pue,brandy & & [8,38] & 2.2 & [3] & 3.5–6.7 & [3] \\
3-phenylpropionate & Floral, sweet, frinity & [3,83] & 4600 & [3] & 60.9–4490 & [3,50] \\ Ethyl decanoate & Brandy, fruity, grape, chemical & [3,83,85–87] & 441 & [3] & 491–892 & [3] \\ Ethyl dodecanoate & Sweet, floral, fruits, cream & [8,38,87] & 1.8 & [3] & 52–10.3 & [3,9] \\ Eugenol & Cimnnn, cloew, honey & [84,87,88] & 20.3 & [3] & 1.22–61.0 & [3,9,50] \\ Linalo & Citrus, floral, sweet, Inverder & [8,38,87] & 20.3 & [3] & 1.22–61.0 & [3,9,50] \\ Geramid & Floral, sweet & [3] & 12.7 & [3] & 105–61.4 & [3,9] \\ \(\alpha\)-Terpineol & Lilas, floral, sweet & [83–86] & 20.1 & [3] & 10.1–852 & [3,9] \\ \hline \multicolumn{6}{c}{ad: not detected} \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Twenty-two volatile compounds that have been reported to be common in grape spirits and Port wine. The aroma descriptors and the concentration ranges in grape spirits and Port wine are also included. According to the IVDP, there are specific aromas that are valued in the various Port wine styles [1]. For instance, young Port wines have characteristic fruity and floral aromas, and these aromas may evolve and change through ageing in oak barrels, which then provide distinct and unique complex aromas to aged Port wine, such as honey, dry fruit, spicy and nutty [1,19]. Thus, from all of the volatile compounds reported in Port wines (Tables S1 and S2), a selection was performed, taking into consideration the ones with the aromas related to the six classes of aromas that are appreciated in the various Port wine styles: spicy, woody, sweet, fruity, nutty and floral [1]. Thus, Figure 5 was constructed using two main types of information: one side with the six classes of valued aromas in Port wines, and on the other side the range of the olfactory thresholds (based on data reported in Table S2). Each volatile compound was distributed according to its aroma descriptor(s) and the respective reported olfactory threshold in Port wine (limited data are available for this matrix) or in hydroalcoholic matrices, ranging from few \(\upmu\)g/L to g/L. This organization allowed us to visualize which volatile compounds may be responsible for specific aromas and their potential sensorial impact, since the lower the olfactory threshold, the higher the potential sensorial impact that volatile compound may have in Port wine.