Improvement of non-Saccharomyces yeast dominance during must fermentation by using spontaneous mutants resistant to SO₂, EtOH and high pressure of CO₂

Botrytis cinerea, a fungal pathogen commonly known as grey mold, which under specific climatic conditions can develop into a desirable form known as noble rot. In this process the fungus penetrates the grape skin, allowing water evaporation and concentration of sugars and flavors, while profoundly affects the metabolite composition of grapes, leading to the production of unique and desirable compounds in the resulting wines. The result is a unique and complex wine with a luscious sweetness, heightened aromatics, and a distinct character.

Production of volatile compounds by yeast is known to be modulated by must nitrogen. Nevertheless, various parameter of must quality have an impact on yeast fermentation. In this study we propose to evaluate the impact of nitrogen / lipids balance on a Sauvignon Blanc grape juice (Val de Loire).
Must was prepared from the same grapes at pilot scale. Three modalities were carried out: direct pressing, direct pressing with a pre-fermentation cold stabulation and pellicular maceration before pressing.

The chemistry of wine is notably complex and is modified by ageing of the bottles. The composition of wines is the result of vine production (under the influence of vintage, climate and soils); yeast production (under the influence of juice composition and fermentation management); lactic bacteria production (under the influence of young wine composition and malolactic fermentation management); and of the ageing process either in vats, barrels or bottles or both. The composition is linked to the quality perceived by consumers but also to their origin, sometimes associated to the “terroir” concept.

Regulated deficit irrigation (RDI) is a common viticultural practice for wine grape production. In addition to the potential improvement of water use efficiency, the adoption of this technique favors smaller canopies with higher levels of fruit sun exposure, enhancing quality attributes associated with red wine grapes such as smaller berries with higher tannins and anthocyanins. However, these quality attributes do not necessarily transfer to white wine grapes. The goal of this project was to assess whether partial rootzone drying (PRD) is more suited than RDI to grow high-end white wine grapes in arid climates, especially aromatic varieties, using Riesling as a model.

S’il n’existe pas de réglementation officielle, la démarche des vins naturels prône un retour aux pratiques dites ancestrales préconisant notamment un mode d’élaboration des vins utilisant le moins d’intrants possible. Le seul autorisé reste l’anhydride sulfureux (SO2) à des doses quatre à cinq fois moins importantes que pour les vins dits conventionnels. Ce désir de renouer avec