González-Neves Gustavo, Favre Guzmán, Piccardo Diego,
Facultad de Agronomía. Universidad de la República. Uruguay
Email contact: gustavogn[@]fagro.edu.uy
The aim of this work was to study winemaking alternatives that will optimize the quality of the Tannat wines, taking advantage of the grape's oenological potential.
Alternatives of winemaking were studied using Tannat grapes with different composition and sanitary status. The grapes were harvested at technological maturity. The sanitary status of the grapes was evaluated using commercial tests, absorbance measurements at different wavelengths and analysis of the gluconic acid and glycerol contents. The wines were made in triplicate by traditional winemaking, with and without oenological tannins, or by thermo-maceration. The wines were analyzed 3 months after vinification, determining their general composition, color and polyphenolic composition.
The highest color intensity was obtained in the wines produced with the hot pre-fermentative maceration (HPM). The effect of HPM on anthocyanin and proanthocyanidin content was very significant, showing the higher extraction of these compounds and their lower degradation in oxidation reactions. The values obtained in some cases were exceptionally high, showing the potential of the application of this technique in this grape variety. In most of the trials, the color intensity of the wines with added tannins was greater than that of the controls. The addition of tannins determined a lower anthocyanin content than the control wines, which could be related to the increase in condensations between these molecules.
The pre-fermentative hot maceration was a totally effective treatment to inactivate the oxidative enzymes, in addition to increasing the extraction of compounds from the skins and seeds. Because of its application, wines with significantly higher color intensity and phenolic contents were obtained. The addition of oenological tannins proved to have a positive effect on the color and phenolic contents of the wines, but its maximum effectiveness was achieved with remarkably high doses. The effect of the different techniques evaluated was according to the oenological quality and the sanitary state of the grapes, so new research is required to verify the effect of these techniques in other situations and for other grape varieties.
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