As part of their studies on global warming, in 2019 the Technical Department of Inter Rhone studied the impact of the harvest date on the sensory profile of Viognier and Grenache blanc. Differing levels of maturity among these varietals were studied, in order to determine the impact of ripeness on the final sensory profiles of the resulting wines. Setting the optimal harvest date is crucial for the future quality of the wines, taking into account technological maturity (balance acids and sugars), phenolic maturity (anthocyanin and tannin quality), and aromatic maturity (revelation of varietal aromas). One plot of Viognier and one plot of Grenache were used to form the basis of the study, with winemaking taking place in the experimental cellar of Inter Rhone.
Grapes of varying maturity were vinified separately, using a standard and identical protocol. Blind tasting was conducted by Inter Rhone’s expert jury, 8 months after vinification. The results clearly showed significant variation in organoleptic profile. In Viognier, the early harvest created an acidic wine, which was not very expressive and lacked roundness. Conversely, a late harvest gave the wine an aromatic profile, more expressive but heavier on the palate and lacking liveliness. The best compromise appears to be found in wine made from the September 6 harvest, which provided an interesting balance, freshness and aromatic complexity.
Grenache Blanc was more precisely affected by harvest date. The balance seems really different with only 7 days between harvests. The earlier harvest produced a more expressive wine, with more fruit notes, and significantly higher acidity. Wine from the later harvest was less fruity on the nose and the palate showed reduced acidity, reduced bitterness, an elevated fat element and more heat. For this grape, the technical maturity differences are low between the harvest dates, but the impact on the organoleptic profile is clear, with the earlier date producing a more interesting wine.
Obviously, sanitary and fermentation conditions remain important factors in the resulting wines; however, the importance of the correct date of harvest cannot be underestimated.