Bilan hydrique: une méthode proposée pour l’évaluation des réserves hydriques dans le zonage viticole

Several studies have tried to develop different methods to study the photodegradation of wine in an accelerated way, trying to elucidate the effect of light on the wine compounds[1]. In a previous study, our team developed a chamber that speeds up the photodegradation of rosé wine[2]. In the present work we have tried to establish a correlation between irradiation times in accelerated conditions and the natural exposure to the cycles of light that usually exist in markets or at home.

Molecular markers of wine oxydation, such as sotolon or Strecker’s aldehydes that induce respectively nut or curry and boiled vegetables or wilted rose odors, can be percieved as a default by consumers. These volatile compounds are especially formed during the premature aging of wine, but it is likely that several contributing compounds are still unknown as is their combined contribution. This study was carried out to identify the markers of oxydation in Chardonnay wine by Gas Chromatography Olfactometry (GC-O) and to study the impact of these markers on the complex wine aromatic buffer using the Olfactoscan approach.A Chardonnay wine (2018-vintage), taken after malolactic fermentation without sulphites addition, was submitted to an artificial oxidation to simulate more or less prononced premature oxidation. Volatile compounds were extracted by Solid-Phase Extraction (SPE) and analysed by GC-O with a panel of 13 trained subjects. The same extract was also submitted to a second analysis based on the Olfactoscan technique, which allowed to evaluate the impact of each volatile compounds on the complex aromatic buffer of a non-oxidized wine delivered as background odor. Preliminary results revealed three types of behavior. On the one hand, several odor zones appeared only with the background odour, suggesting a synergy effect induced by the compounds in the aromatic buffer. Conversely, odor-active compounds could not be perceived within the background odor suggesting a masking effect. Finally several compounds were found to contribute as key odorants for wine oxydation once mixed with the aromatic buffer. These compounds are still to be identified using complementary techniques.

Sulphur dioxide (SO2) seems indispensable in winemaking because of its properties. However, a current increasing concern about its allergies effects in food product has addressed the international research efforts on its replacement. This supposes a sufficient knowledge of its properties and conditions of use. Several studies compared SO2 properties against new alternatives that are supposed to overcome SO2 disadvantages. Firstly, the state of art on SO2 wine replacements is revised, and secondly, the last promising results using natural enriched polyphenol extracts are shown.

Astringency is an important red wine quality attribute, which can be measured both chemically and sensorially. The use of tannin activity shows potential as a valuable chemical measurement in understanding red wine mouthfeel properties such as astringency and bitterness, which is also affected by tannin structural factors, in addition to matrix effects. Tannin activity is defined as the enthalpy of interaction between tannins and a hydrophobic surface. Studies involving tannin activity have been performed since the early 2010’s, but chemosensory studies used to evaluate how structure-activity relationships change across multiple, consecutive vintages are limited. The aim of this study is to investigate how tannin activity may be linked to red wine mouthfeel, and how all these variables may change according to wine age.

Clarification or fining of wines is a technique used in wineries to eliminate unwanted wine components, which negatively affect its quality. Clarification normally involves the addition of an adsorptive material that eliminates or reduces the presence of undesirable components. The problem is that many of the fining agents used in the industry contain allergens, such as caseinates or ovalbumin.