Comportement phénologique et végétatif de la cv “Italia” en rapport an climat dans les deux zones typiques de viticulture de table en Sicile

With climate change, it is progressively more often to obtain grapes with an acceptable content in sugars or acids but with immature tannins described as green, aggressive or hard (noted as GAH onwards). During winemaking, the oenologist has to make decisions related to the elaboration of such grapes based mainly on empirical experience, given the lack of objective criteria to this concern. An increase in the chemical and sensory knowledge of immature tannins would allow managing this GAH character of grapes with the maximum possible efficiency during winemaking processes. The present work aims at isolating and identifying the group of compounds responsible for the GAH character present in wines.

Right after the pouring of wine in a glass, a myriad of volatile organic compounds, including ethanol, overwhelm the glass headspace, thus causing the so-called wine’s bouquet [1]. Otherwise, it is worth noting that during wine tasting, most people automatically swirl their glass to enhance the release of aromas in the glass headspace [1]. About a decade ago, Swiss researchers revealed the complex fluid mechanics underlying wine swirling [2]. However, despite mechanically repeated throughout wine tasting, the consequences of glass swirling on the chemical space found in the headspace of wine glasses are still barely known.

Background: Polyphenols extracted from skins and seeds showed different sensory attributes including astringency and bitterness. In previous studies, it has been demonstrated that extracts obtained either from skins or seeds interact differently with salivary proteins.

Grape seeds account for around 5% of the weight of the whole grape berry, representing approximately 40%-50% of the solid by-products that the different wine industries generate during the winemaking process.

Aging on lees (AOL) has been used for wine aging for a long time, thanks to its ability to modify wine composition, improving sensory characteristics and stability. However, the prolonged contact with fermentation lees may increase the risk of developing sensory defects, due to the growth of unwanted microorganisms. Furthermore, AOL requires a large amount of work to manage bâtonnage and for topping up the barrels, significantly increasing production costs.