Short-Term CO 2 Treatment of Harvested Grapes ( Vitis vinifera L., cv. Trebbiano) before Partial Dehydration Affects Berry Secondary Metabolism and the Aromatic Profile of the Resulting Wine.

High CO 2 concentrations applied to harvested horticultural products can modify primary and secondary metabolism. This work reports the metabolic responses to short-term CO 2 treatments of white-skinned grapes (cv Trebbiano) undergoing postharvest partial dehydration. The influence of CO 2 treatments on the aroma profile of the derived sweet wine was also assessed. Harvested grapes were treated with gaseous CO 2 (30%) or air (control) for 24 h and then dehydrated (about 45% of weight loss) before vinification. Lipophilic and phenolic compounds of grape skin and the wine aroma profile were analyzed. In CO 2 -treated berries, the lipophilic and phenolic compounds decreased at a reduced and faster rate, respectively, during dehydration. Aroma profile of wine from CO 2 -treated grapes showed a slight but significantly higher content of glycosylated C13 and terpene compounds, and a decrease/absence of free acids, vanillin derivates and other phenol volatiles. The higher content of volatile alcohols in wine from treated berries suggests that the alcoholic fermentation was triggered. CO 2 application before the withering process of Trebbiano grapes affects the aroma profile of the resulting wine by altering the free:glycosylated volatiles ratio. This study provides information on the possible use of CO 2 as metabolic elicitor to modulate the aroma profile of the resulting wines obtained after grape dehydration.