Winter physiology in a warmer world: Cold hardiness and deacclimation sensitivity drive variation in spring phenology

With climate change, the occurrence of wildfires has increased in several viticultural regions of the world. Subsequently, smoke taint has become a major issue, threatening the sustainability of the wine industry.

The Cognac region is expanding, driven by the success of its renowned brandy and the demand for high grape yields to ensure a steady supply of base wine for distillation. Ugni blanc, the most widely planted grape variety, relies on rootstocks for soil and climate adaptation, providing essential nutrient supplies to the scion. Understanding the impact of rootstocks on key berry components, such as sugars and nitrogen compounds, is crucial. These compounds serve as primary precursors for the production of fermentative aroma metabolites, which, in turn, act as quality indicators for eau-de-vie.

Winegrape cultivars are particularly sensitive to temperature and recent changes in climate have advanced the onset of berry ripening, resulting in unbalanced fruit composition at harvest.

Malolactic fermentation (MLF) is a secondary step in the vinification process and it follows alcoholic fermentation (AF) which is predominantly carried out by Saccharomyces cerevisiae. These two processes result in the degradation of metabolites to produce secondary metabolites which also contribute to the final wine flavour and quality. AF results in the production of ethanol and carbon dioxide from sugars and MLF stems from the degradation of L-malic acid (a dicarboxylic acid) to L-lactic acid (a monocarboxylic acid). The latter process results in a smoother texture as the acidity of the wine is reduced by the process, it also adds to the flavour complexity of the wine.

Wine is a complex matrix whose composition depends on climatic, agricultural, and winemaking factors, making quality control and authenticity assessment critical in the global market.