Under-vine management effects on grapevine production, soil properties and plant communities in South Australia

The wine industry generates each year 20 million tons of by-products. Among them grape pomaces represent a big part that can be considered as a source of potentially bioactive molecules such as polyphenols. Kombucha fermentation is an ancestral process which allow to increase the biological properties of tea by the action of a microbial consortium formed by yeasts and bacteria called scoby.

All along the red winemaking process, many microorganisms develop in wine, some being beneficial and essential, others being feared spoilers. One of the most feared microbial enemy of wine all around the world is Brettanomyces bruxellensis. Indeed, in red wines, this yeast produces volatile phenols, molecules associated with a flavor described as “horse sweat”, “burnt plastic” or “leather”. To produce significant and detectable concentrations of these undesired molecules, the yeasts should first grow and become numerous enough. Even if the genetic group of the strain present and the cellar temperature may modulate the yeast growth rate¹ and thus the risk of spoilage, the main factor seems to be the wines themselves, some being much more permissive to B. bruxellensis development than others.

The application of different winemaking techniques helps to modify the basic parameters, phenolic profile, and aroma components influencing the final wine quality. In particular, pre-fermentative processes aim to increase the extraction and preservation of grape native compounds. Among them, cold liquid stabulation (macération sur bourbes) consists in maintaining the grape juice on its lees, in suspended condition at low temperature (0-8 °C) for a variable time (generally from 7 to 21 days). The aim of this work is to apply the cold liquid stabulation on two Italian white grape varieties, Arneis and Cortese, to evaluate the impact on basic parameters, color, polyphenolic compounds (TPI), antioxidant power (DPPH), total polysaccharides, and free and glycosylated volatile compounds (GC-MS analysis) during and after the process.

Phenolic ripening represents a major interest for quality wine producers. Nevertheless, climatic or genotypical limitations can often prevent optimal maturation process. During winemaking seeds can be easily separated and technologically processed to improve their quality.

Botrytis cinerea (Bc) is one of the main pathogens affecting the cultivated grapevine. A key role in grapevine tissue colonization is played by cell wall (CW) remodeling driven by CW Modifying Enzymes (CWMEs), expressed both by the host and the pathogen. Their action can impact CW integrity and trigger specific immune signaling, thus influencing Bc infection outcome. To further characterize the role of the CW in the grapevine response to Bc, two contrasting genotypes in their resistance to the fungus were artificially inoculated at full bloom. RNA-seq analysis and biochemical characterization of the CW and its modification in samples collected at 24 hours post-inoculation highlighted significant differences between genotypes.