# Madeira Wine Volatile Profile. A Platform to Establish Madeira Wine Aroma Descriptors
## 2 Results and Discussion
### Potential Impact Odorants of Madeira Wines
#### 2.1.1 Young Madeira Wines  
Taking into account the OTs [6; 31; 32; 33; 34; 35; 36] and odor descriptor [6; 37; 38; 39; 40; 41; 42; 43; 44; 45] reported in Table 1, as well as the relative concentration of VOCs (Tables S1 and S2), the citrus odor characteristic of Malvasia, Sercial and Tinta Negra wines (Table 2) could be explain by the presence of some terpenic compounds, such as \(\alpha\)-pinene, limonene,linal, citronellol, geraniol, and some esters, like hexyl acetate, ethyl 3-methylbutanoate and ethyl 3-hydroxyexanoate, and 2-ethylhexan-1-ol (Table 3). All these varietal and fermentative compounds are present in Malvasia, Sercial and Tinta Negra wines at relative concentrations higher than their respective OT. \(\alpha\)-Pinene, linalool, citronellol, geraniol, \(\beta\)-cyclocitral, 1,2-dihydro-1,1,6-trimethylnapthalene (TDN), \(\beta\)-damascenone, geranyl acetone, \(\beta\)-ionone, 1-hexanol and 2-phenylethyl alcohol (Pavay Serial and Crystal)  
Nevertheless, 2-furfurral (OT = 14,100 ug/L), 5-methyl-2-furfurral (20,000 ug/L), and \(\gamma\)-butylrolactone (OT = 35,000 ug/L) could not be used to explain the caramel descriptor since their relative concentration (Tables S1 and S2) was lower than their respective OTs (Table 1). [PERSON] et al. [6] reported that furfural, 5-methylfurral, 5-hydroxymethylfurral and 5-ethoxymethylfurral were not detected in the GC-O assays, in spite of the fact that these furanic compounds are quantitatively important, are not relevant to the aroma of Madeira wine. Moreover, phenylacetaldehyde, stotolon, (Z)-whiskylactone and some volatile phenols from wood are important odor active compounds in Madeira wines [6]. In the current study, from these three VOCs, only (Z)-whiskylactone was detected. Thus, based on the OTs, ethyl butanoate, \(\gamma\)-octalactone and (Z)-whiskylactone could be the VOCs responsible for the caramel descriptor characteristic of older Malvasia, Bual and Tinta Negra wines, since their relative concentrations (Tables S1 and S2) were higher than their OTs. The ethereal descriptor characteristic of Verdello wines suggests the presence of ethyl lactate and ethyl pyruvate. Perhaps, these two VOCs were also presented in all Madeira wines analyzed, the relative concentration of ethyl pyruvate in Verdello wines (on average 3.54 ug/L) was higher than the remaining Madeira wines (on average 1.49 ug/L). The presence of hexyl acetate, 2-phenylethyl alcohol, 5-(ethoxymethyl) furfural and eugenol could explain the spicy notes characteristic of old Madeira wines, since their relative concentration was higher than their respective OTs (Table 1). Other VOCs that could explain the spicy notes were ethyl pyruvate and ethyl salicylate, however no information related to their OTs is available. 2-Acetylfuran, 5-methyl-2-furfural and (Z)-whiskey lactone could explain the toast odor, as their relative concentration increased remarkably during aging process (Tables S1 and S2). Nevertheless, taking into account the relative concentration and OTs, (Z)-whiskey lactone is the potential odorant responsible for the toast notes characteristic of older Madeira wines. The vanilla odor related to Malvasia and Sercial wines could be explained by the presence of ethyl 2-fluoroate, vanillin and methyl vanillate, since a remarkably increase on relative concentration was observed for vanillin and ethyl vanillate during aging process. Vanillin is the one of the VOCs that could explain the vanilla descriptor, since its relative concentration was higher than their OT (Table 1). \(\delta\)-Cadinol, and acetals, like 1,1-diethyloxyethane, _cis_-dioxane, _cis_-dioxolane and _trans_-dioxane could explain the wood descriptor characteristic of older Madeira wines, as their relative concentration slightly increased during aging  
Figure 3: Total relative concentration (ug/L) of major (**a**) and minor (**b**) chemical families identified in Madeira wine. process (Tables S1 and S2).