Angelita Gambuti,* Luigi Picariello, Luigi Moio, and Andrew L. Waterhouse 
*University of Naples Federico II, Vine and Wine Division – Viale Italia,
83100 Avellino, Italy (angelita.gambuti@unina.it)

Wine aging is an oxidative process regulated by wine initial composition, the presence of exogenous antioxidants, and total oxygen exposure. Although acetaldehyde is important for wine evolution, factors involved in its production, consumption, and possible relationship with changes in phenolic compounds remain unclear. In a first experiment, the role of initial phenolic composition was examined with a forced oxidation simulating one year of barrel aging using wines with different anthocyanin/tannin ratios. In a second experiment, the same approach was used to evaluate the role of different enological tannin preparations (ellagi- gallo- and condensed tannins). In a third experiment, Cabernet Sauvignon wines previously treated with sulfur dioxide and glutathione and submitted to microoxygenation (Gambuti et al. 2015 AJEV), were bottled and analyzed after three years aging un-der controlled conditions. Wines with lower anthocyanin/tannin ratios produced less acetaldehyde and more polymeric pigments. Adding exogenous tannins has determined instead a greater production of acetaldehyde and an increase of the level of polymeric pigments in wine; ellagitannins were most efficient. In all wines analyzed, a successive dramatic consumption of acetaldehyde was observed. Acetaldehyde levels and color stability of wines after three years of aging were strongly affected by prebottling oxygen exposure: wines that were microoxygenated and less protected by sulfur dioxide and glutathione were richer in highly reactive compounds and stable polymeric pigments. In all experiments, for all variables considered, significant changes in tannins reactive to proteins were observed. These results confirm the role of acetaldehyde as a trigger compound for reactions that stabilize color and condense tannins.

Funding Support: Provincia di Avellino