EFFECTS OF HYDROXYTYROSOL ON THE CHEMICAL PROFILE AND SENSORY ATTRIBUTES OF A RED TUSCAN WINE

The composition of grape berry cell walls was studied on two grape varieties, two years and two maturation levels at the same time as the extraction of anthocyanins and tannins. The chemical composition of skins, seeds, and pulps, focused on polyphenols and polysaccharides, was compared to the chemical composition in polyphenols after extraction from the skins in model solutions or after wine making of the berries. Polyphenols were mainly characterized by UPLC-MS and HPLC-SEC. Polysaccharides were characterized by analysis of the neutral sugar compositions, and also by the CoMPP (comprehensive micropolymer profiling) analysis, a new method which targets the functional groups of cell wall polysaccharides.

Varietal innovation is a major lever for meeting the challenges of the agro-ecological transition of vi-neyards and their adaptation to climate change. To date, selection work has already begun in the Bordeaux region through the Newvine project. The aim of this project is to create new vine varieties with resistance to mildew and powdery mildew, adapted to the climatic conditions of the Bordeaux region and enabling the production of wines that are in line with consumer tastes and the expected typicity of Bordeaux wines.

In economics, the perception of wine quality is not limited to sensorial characteristics: an indication of the region of production significantly affects the perception of quality and consumers’ WTP ([1]; [2]). However, [3] or more recently [4] show that even if a wine has an organic label, the taste of wine remains the predominant criterion in consumer preferences. The contribution of our experiment is to evaluate the impact of responsible attributes (organic label, Non Added Sulfites, HVE certification) on the appreciation of several red wines on the market. More than 280 consumers participated to the present study and they perform 25 tastings divided into 5 different sessions. 20 different red wines from Bordeaux Area are tasted.

During wine aging many compositional changes take place. In particular, aroma undergoes dramatic modifications through a wide range of reactions that to date are only partly understood. Italy owns one of the largest ampelographic heritages worldwide, with over three-hundred different varieties. Among these, many white grapes are employed for the production of dry still white wines. Some of these wines are consumed young while others are more prone to aging. For many of these wines, the aging patterns related to volatile composition are still unknown.

Light-struck taste (LST) is a wine fault that can occur in white and sparkling wines when exposed to light. This defect is mainly associated to the formation of methanethiol and dimethyl disulfide due to light-induced reactions involving riboflavin (RF) and methionine [1]. The presence of RF in wine is mainly due to the metabolism of yeast [2] which fermenting activity can be favoured by using yeast derivative products (YDPs) as nutrients. Nonetheless, a previous study showed the addition of YDPs before the alcoholic fermentation (AF) led to higher concentrations of RF in wines [3]. Due to the widespread use of YDPs in the winemaking process, this study aimed to understand the possible relation between the content of RF in wine and the YDP adopted as nutrient for AF.