How climate change can modify the flavor of red Merlot and Cabernet-Sauvignon

The main goal of this research was to identify key aroma compounds linked with the maturity of grapes (ripe and overripe) and involved in grapes and wines with an intense dried fruits aroma. Odoriferous zones reminiscent of these aromas were detected by gas chromatography coupled with olfactometry (GC-O). Three odoriferous zones were identified (OZ1, OZ2, OZ3). Using GC-MS with chemical standards, they were identified as (Z)-1,5-octadien-3-one (geranium), furaneol (caramel) and γ-nonalactone (coconut, cooked peach), respectively. Studies of their sensory properties and quantitative assays by GC-MS (EI/CI) in musts and wines were performed.

Furaneol and γ-nonalactone are well-known compounds in wines but have only rarely been reported in musts. On the contrary, the influence of (Z)-1,5-octadien-3-one on the aroma of must is reported for the first time. The perception threshold of this ketone in must is 1.2 ng/L and its concentration can exceed 200 ng/L in overripe merlot grapes. High concentrations of furaneol and γ-nonalactone were detected in musts and young red wines marked by dried fruit flavors. We also report the first results concerning the incidence of harvest date of Cabernet-Sauvignon grapes on the aromas and fine composition of musts and wines.