Caractérisation du terroir en Espagne : méthodologie de l’évaluation et de la validation

Red grape pomace can be an important source of polysaccharides, but currently they are little studied and even less with viable and environmental extraction processes (green extraction). These green techniques must be able to break the cell wall so that the compounds contained in the cells, including polysaccharides, are released and can have a great influence on extraction yields, the chemical structure of polysaccharides and applications in wines. Amongst the emerging green techniques most applied to the extraction of bioactive compounds, such as polysaccharides, high-power ultrasound (US) and enzyme-assisted extraction stand out.

In Castilla-La Mancha as other winegrowing regions, vineyards suffer the effects of the global climate warming. Severe spring and summer droughts are increasingly frequent, which concur with the phenological stages most susceptible to water and temperature stress. Under these conditions, irrigation use is required in order to ensure the vineyard growing sustainability. However water resources are increasingly limited, for this reason is required to choose cultivars displaying high water use efficiency.

Under current climate change pressures, obtaining grapes with adequate acidity at harvest is one of the main challenges for growers, especially if the goal is producing sparkling wines. This issue arises from two main occurrences: i) higher temperatures enhance degradation of malic acid; ii) grape maturity may occur under suboptimal climatic conditions due to an advanced phenology.

Oenococcus oeni is the main Lactic Acid Bacteria responsible for malolactic fermentation, converting malic acid into lactic acid and carbon dioxide in wines. Following the alcoholic fermentation, this second fermentation ensures a deacidification and remains essential for the release of aromatic notes and the improvement of microbial stability in many wines. Nevertheless, wine is a harsh environment for microbial growth, especially because of its low pH (between 2.9 and 3.6 depending on the type of wine) and nutrient deficiency. In order to maintain homeostasis and ensure viability, O. oeni possesses different cellular mechanisms including organic acid metabolisms which represent also the major pathway to synthetize energy in wine.

The effects of different methods of soil management on the nutrient supply and the wine quality of organically grown Grüner Veltliner grapevines (wide-spaced high culture training system) were investigated in the winegrowing region Wagram of Lower Austria (municipality: Großriedenthal).