3.1.5. Terpenes and norisoprenoids
Terpenes and C13-norisoprenoids are the most important aromatic compounds and generate the ‘varietal aroma’ of wines with relatively low thresholds. These powerful groups of odorants are generally present in grapes as glycosides but can be released during winemaking through the action of endogenous or exogenous glycosidase enzymes. Three substances (styrene, eugenol and trans-rose oxide) and one C13-norisoprenoids (b-damascenone) were detected in both wines. Their levels were higher in SF wine than in IF wine, especially trans-rose oxide, which reached 0.48 mg/L but was not detected in IF wine. The OAV of b-damascenone was 14.22 in SF wine, which was 50.2% higher than that in IF wine.