Aroma evaluation of wines from early-harvested grapes in view of climate change

This study evaluated the aromatic expression of Barbera and Pinot Noir wines produced from early-harvested grapes and analyzed after 3 months in bottle. Three different grape ripening levels were assessed (-15, -7 and 0, indicating the days before full-ripeness), in order to 1) define the peak of concentration of the most relevant volatile compounds in grapes; 2) understand the relation between volatile and sugar concentrations in Pinot noir and Barbera grapes; 3) meet the demand for wines with both reduced alcohol content and balanced organoleptic properties. Main technological parameters of grapes (soluble solids, pH and polyphenolic content) were assessed, as well as important key aromas of must and wines. Attention was focused on beta-damascenone, beta-ionone and alfa-ionone which were quantified using a stable isotope dilution assay (SIDA)_HS-SPME/GC-MS method, whereas the most important free and glycosylated aromatic compounds were quantified by SPE/GC-MS. As regards soluble solids, Barbera grapes presented a continuous accumulation trend and significant differences of about 2 °Brix between the three ripening levels, while relatively to the polyphenolic content no differences were noted in both varieties. Pinot noir wines were characterized by a higher concentration of beta-damascenone compared to Barbera wines. The highest beta-damascenone content was noticed in the wines produced with 7 days early-harvested grapes for both cultivars; no differences were revealed for beta- and alfa-ionone contents. As to fermentative compounds, the lowest ethyl ester concentrations were found in Pinot noir wines produced with overripe grapes, whereas no significant differences were noticed in Barbera wines obtained from grapes with different ripening levels. Glycosylated compounds, mainly terpene and C13 precursors, were more abundant in wines from early-harvested grapes. Finally, the concentration of beta-damascenone in wines after 3 months in bottle was inversely related to their polyphenolic content measured at the end of fermentation.