INFLUENCE OF GRAPE RIPENESS ON MACROMOLECULES EXTRACTABILITY FROM GRAPE SKIN TISSUES AND GRAPE SEEDS DURING WINEMAKING

The balance between the different flavours of a wine largely determines its perception and appreciation by the consumers. In white wines, sweetness and sourness are usually the two poles balancing the taste properties. The bitter flavour, on the other hand, is frequently associated with a loss of equilibrium and all white wines (dry and sweet, young and aged) are affected.
Several bitter compounds are already well-described in wines.

The presentation will approach the understanding of wine consumers´ perception based on the experiential model suggested by Warell (2008). In this framework, wine consumption gives rise to a
variety of experiences related to the perception, understanding, and judgment of the product. These
multidimensional facets of the drinking experience can be explored by measuring affective, cognitive,
and sensory responses of consumers, which are shown to be stable regardless of the social context.

Nitrogen (N) fertilizer is important for grape growth and the quality of wine. It is essential to address the mismatch between N application and wine composition. Cabernet Gernischt (Vitis vinifera L.), as one of the main wine-grape cultivars in China, was introduced to Yantai wine region in 1892. This grape cultivar is traditionally used for quality dry red wine with fruit, spices aroma, ruby red and full-bodied wines. In order to regulate vine growth and improve grape and wine quality, Cabernet Gernischt grapevines were subjected to decreased levels of N treatments, compared to normal N supply treatment, during grape growing seasons of 2019 and 2020.

From the chemical angle, Champagne wines are complex hydro-alcoholic mixtures supersaturated with dissolved carbon dioxide (CO₂). During the pouring process and throughout the several minutes of tasting, the headspace of a champagne glass is progressively invaded by many chemical species, including gas-phase CO₂ in large majority. CO₂ bubbles nucleated in the glass and collapsing at the champagne surface act indeed as a continuous paternoster lift for aromas throughout champagne or sparkling wine tasting [1]. Nevertheless, inhaling a gas space with a concentration of gaseous CO₂ close to 30% and higher triggers a very unpleasant tingling sensation, the so-called “carbonic bite”, which might completely perturb the perception of the wine’s bouquet.

Wine varietal aroma is the result of a mixture of compounds formed or liberated from specific grape-aroma precursors. Their liberation/formation from their specific precursors can occur spontaneously by acid catalyzed rearrangements or hydrolysis or by the action of the yeast enzymatic activities. The influence of yeast during fermentation on the production of these volatile compounds has been widely studied however, the effect of this influence during aging is not fully understood. In order to evaluate these processes several indirect strategies have been used to study aroma precursors although they are not useful to understand the chemistry of the process.