Environmental influence on grape phenolic and aromatic compounds in a Nebbiolo selection (Vitis vinifera L.)

Among the macromolecules of enological interest in white wines, much attention has been paid to polysaccharides.

Dealcoholization of wine has gained increasing attention as consumer preferences shift toward lower-alcohol or
alcohol-free beverages. This process meets key demands, including health-conscious lifestyles, regulatory
compliance, and the expanding non-alcoholic market [1-3].

Vine clone selection aims at the survival of clones with particularly desireable attributes for the production of high quality wines. The purpose of this research was to study the enological potential of the clones of Greek indigenous grape varieties over two vintages, 2018 and 2019.
METHODS: Two clones of the white grape varieties Moschofilero (E26 and E27), Assyrtiko (E11 and 16), Roditis (25E16 and 02E1E21) and two clones of the red grape varieties Xinomavro (19 and E2E30) and Agiorgitiko (03E40 and 41E47) were vinified under the same protocol for the white wines and common for the red wines in 2018 and 2019. The resulting products were studied for several enological parameters such as alcohol content, volatile acidity, pH, total phenolics, anthocyanins and tannins for the red wines, as well as browning tests for the white wines. The aroma profile of these ten samples was investigated through sensory analysis with intensity rating of individual attributes on a five-point scale by a trained panel.

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.

Although the ripening process of grapevine berries is well-documented at the vineyard level, pinpointing distinct developmental stages remains challenging. The asynchronous development of berries results in dynamic biases and metabolic chimerism. It is thus crucial to consider individual berries separately and resynchronize their internal clock for deciphering physiological changes throughout development. Given the importance of grape composition in wine quality, we aimed at measuring developmental changes in the metabolome of Syrah single berries from anthesis to over-ripening, without a priori preconceived.