Aspetti legislativi di settore: e politiche comunitarie

Flavonoids, including flavonols, anthocyanins, and tannins, are
important contributors to grape and wine quality, and their biosynthesis is strongly influenced by bunch microclimate. While the synergistic effect of light and temperature has been intensively examined on flavonoids in relation to bunch exposure, studies targeting the sole effect of high temperature have mostly
focused on anthocyanins during the ripening period. With tannin biosynthesis starting around flowering, heatwaves occurring earlier in the grape growing season could be critical. Only a few papers report the impact of temperature on tannin synthesis and accumulation; to date, none have examined the effect of high temperature extremes which, in the context of climate change, relates to increases in heatwave intensity.

Nous savons tous très bien qu’on a assisté au cours de ces dix dernières années à une éclosion soudaine de recherches sur le zonage viti-vinicole qui, à partir par exemple du modèle du concept de “terroir”, se sont de plus en plus enrichies en passant aux “Unités ou Systèmes de Transformation” (UTTE) et “Valorisation” (UTCE) pour terminer avec les “Systèmes productifs globaux du Territoire” (UTB) comprenant en filière les aspects existentiels (UTBES), sociaux (UTBSO) et économiques (UTBEC) hypothisés dans le “GRANDE ZONAZIONE: Grand zonage” (MORLAT R., 1996, CARBONNEAU A., 1996, TOUZARD J.M. 1998, CARBONNEAU A., CARGNELLO G., 1996, 1998, CARGNELLO G., 1994, 1995, 1996, 1998, 1999, 2001, -MILOTIC A., CARGNELLO G., PERSURIC G., 1999, PERSURIC G., STAYER M., CARGNELLO G., 2000, MILOTIC A., OPLANIC M., CARGNELLO G., PERSURIC G., 2000).

Fungal chitosan is a polysaccharide made up of glucosamine and N-acetyl-glucosamine and derived from chitin-glucan of Aspergillus niger or Agaricus bisporus. Fungal chitosan has been authorized as an antiseptic agent in wine since 2009 (OIV) and in organic wine in 2018. At the maximum dose of 10g/hl, it was shown to eliminate Brettanomyces bruxellensis, the main spoilage agent in red wines. Fungal chitosan is highly renewable, biocompatible (ADI equivalent to sucrose) and non-allergenic. However, winemakers often prefer to use sulfites (SO2), though sulfites are classified as priority food allergens, than chitosan. Indeed, many conflicting reports exist regarding its efficiency and its side effects towards beneficial wine microorganisms or wine taste. These contradictions could be explained by the heterogeneity of the fungal chitosan lots traded, the diversity of the wines (chemical composition, winemaking process), but also, by the recently highlighted huge genetic diversity prevailing in wine microbial species.

Proteins play a significant role in the colloidal stability and clarity of white wines [1]. However, under conditions of high temperatures during storage or transportation, the proteins themselves can self-aggregate into light-dispersing particles causing the so-called protein haze [2]. Formation of these unattractive precipitates in bottled wine is a common defect of commercial wines, making them unacceptable for sale [3]. Previous studies identified the presence of phenolic compounds in the natural precipitate of white wine [4], contributing to the hypothesis that these compounds could be involved in the mechanism of protein haze formation.

Malic acid has a strong impact on wine pH and the contribution of fermenting yeasts to modulate its concentration has been intensively investigated in the past. Recent advances in yeast genetics have shed light on the unexpected property of some strains to produce large amounts of malic acid (“acidic strains”) while most of the wine starters consume it during the alcoholic fermentation. Being a key metabolite of the central carbohydrate metabolism, malic acid participates to TCA and glyoxylate cycles as well as neoglucogenesis. Although present at important concentrations in grape juice, the metabolic fate of malic acid has been poorly investigated.