Influence of winemaking techniques on aroma precursors

Nero d’Avola (a red grape) and Fiano (a white grape), traditional not aromatic vines from south Italy, have been subjected to different microvinification processes for the purpose of appraising the effects of technology on the aroma precursor composition (both qualitative and quantitative).The volatile compounds derived from glycosidic precursors of wine odorants have been determined through GC–MS analysis of the extracts, after sample purification followed by enzymatic and acid hydrolysis. The results of the enzymatic and chemical hydrolysis of odorant precursors found in the wines produced from Fiano and Nero d’Avola grapes have highlighted the fact that the terpenic, C13-norisoprenoidic, and benzenoidic qualitative compositions of the different wines, after 12 month storage, are very similar to those determined for the grapes. Nero d’Avola is a variety that synthesizes only a limited quantity of α-terpineol and of its derivatives. Fiano grapes and wines, on the other hand, showed the remarkable presence of α-terpineol, and its derivatives but the absence of some benzenoids and hydroxycitronellol. Moreover, cold skin maceration of Fiano grapes, before settling and alcoholic fermentation, greatly increased the aroma precursors of wines. Only some of the glycosidic precursor ratios, among all those considered suitable for grape characterization, remained identical in wine compared to those of the corresponding grape, since they had not been affected by the winemaking technology adopted.