Effects of Harvest Timing on Selected Aroma-Related Volatile Compounds in Blaufränkisch and Pinot Noir Wines

Harvest timing is an important management factor associated with the volatile composition of wine. This one-vintage study investigated selected free aroma-related volatile compounds in Blaufränkisch and Pinot Noir wines produced under standardised microvinification from grapes harvested at early, standard and late maturity-related stages in four commercial vineyards. Free volatile polyfunctional thiols, six-carbon (C₆) alcohols, free monoterpenes, rotundone and free 13-carbon (C₁₃) norisoprenoids were quantified using gas chromatographic methods, and data were evaluated using exploratory univariate and multivariate statistics. Harvest-stage responses were compound-specific and depended on the investigated grape-variety/regional sample sets. The concentration of 1-hexanol generally decreased with advancing harvest stage, whereas 3-sulfanylhexan-1-ol (3-SH) tended to increase across several vineyard origins. An exploratory pooled correlation between 1-hexanol and 3-SH was weakly negative, indicating only a limited association between the two compounds in bottled wines. Free monoterpenes and free C₁₃-norisoprenoids showed non-linear, compound-dependent patterns, while rotundone showed no consistent overall harvest-stage response. Principal component analysis (PCA) separated the wines mainly according to grape-material background, with additional harvest-stage-related structuring. Overall, under the specific conditions of this one-vintage study, operationally defined maturity-related harvest timing was associated with compound- and background-dependent changes in selected free aroma-related volatile compounds in the investigated red wines.