Intra-varietal diversity in cv. ‘Tempranillo Tinto’: phenological stages

This study evaluates the effect of microwave treatment in grape maceration on the content of free and glycosidically bound varietal compounds) of must and wine and on the overall aroma of wines produced in the presence and absence of SO2.

Organic wines, although resulting from a production method based on the non-use of synthetic phytosanitary products, are not always free of residues. These residues can result from cross-contamination during production in the field or in the cellar, during the production or aging of the wine. In recent years, with the improvement of analysis techniques, a molecule, phosphonic acid, the main metabolite of fosetyl-al (banned in organic farming) is regularly quantified in organic wines and its origin is not clearly identified.

Sulphur dioxide has been used for many years for its antimicrobial, antioxidant and antioxydasic properties in winemaking but nowadays, it is a source of controversy. Indeed, consumers are more attentive to the naturalness of their foods and beverages and the legislation is changing to reduce the total SO₂ levels allowed in wines. To limit and replace the doses of sulphur dioxide applied, winemakers can now use bioprotection consisting in live yeast addition as alternative,seems to be promising. This process, lightly used in from the food industry, allows to colonize the environment and limit the development or even eliminate undesirable microorganisms without altering the sensory properties of the product.

Uruguay is known for the production of Tannat wines, which is a neutral variety from an aroma point of view, but capable of providing aromatic precursors that are of interest in the production of wines for ageing. The main aromatic precursors present are glycosidic compounds and carotenoids. The contribution of carotenoid degradation by-products such as norisoprenoids to wine aroma is fundamental, as they are associated with pleasant aroma descriptors and very low olfactory perception thresholds. Several factors have been shown to influence carotenoid concentrations in grapes, such as cultivar, climatic conditions, viticultural region, plant water status, exposure to sunlight and ripening stage.

The notion of terroir covers multiple components, from geology, pedology, geomorphology and climatology (Doledec, 1995), to aspects that are less well identified but which also intervene in the “typicality” of wines. This justifies the “zoning” approach (Moncomble and Panigaï, 1990) to define homogeneous areas, under the same agro-viticultural management and also identified at the product level (Morlat and Asselin, 1992).