**3.3 Post-fermentative aroma**

This type of aroma includes all volatile compounds formed throughout the aging of the wine, giving rise to what is called "bouquet". During the conservation of the wine, physicochemical and biological reactions transform the aromatic compounds produced in previous stages, so post-fermentative aroma suffers deep changes [79]. Depending on the type of aging, two types of bouquet can be distinguished:


During this stage, the fruity aroma of the wines disappears progressively, evolving towards a more complex aroma. These reactions are slow and limited, sensibly manifesting in the wines after several years.

In this type of wines, there are compounds given by wood such as furans (furfural, 5-methylfurfural, 5-hydroxymethylfurfural) which are responsible for the aromas of roasted almonds [81], phenolic aldehydes (vanilla), phenyl ketones (vanilla aroma), oxygenated heterocycles (caramel aroma), volatile phenols (toasted smell and burnt wood) [82], 4-vinylphenol (carnation aroma), 4-vinylguaiacol (clove aroma), whiskey-lactones (coconut aroma) [83].

*Management of Wine Aroma Compounds: Principal Basis and Future Perspectives DOI: http://dx.doi.org/10.5772/intechopen.92973*

However, some compounds are transformed. During aging, the concentration of monoterpenic alcohols in wine from grapes (linalool, geraniol and citronellol) decreases. On the other hand, the concentration of isomeric oxides, whose olfactory thresholds are higher than the starting alcohols is increased. Hence, there is a loss of varietal aromatic load [84].
