Antiradical activities of some commercial cognacs were evaluated by the DPPH(*) test. Different mathematical models for the evaluation of the antiradical efficiency of the cognac samples were proposed and discussed. Nonflavonoid phenols were found to be the main substances responsible of the radical scavenging activity of cognacs. In particular the strongest correlations between antiradical activity measurements and cognac chemical characteristics was found for ellagitannins, high molecular weight polyphenols, which are extracted from the wood and solubilized in the spirit mainly during first year aging.

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The article evaluates the effect of high-power ultrasound (20 kHz) on the phenolic structure of red wines, to study the possible applications of this innovative technique in wine aging. Different treatment conditions, with times of 1, 3 and 5 minutes and amplitudes of 51, 102 and 153 µm, were applied. In the experimental conditions the main parameters related to the evolution of red wine phenolic compounds show interesting variations; in particular, we found significant differences on tannins evaluated with some indices of tannins reactivity. On the other hand, free anthocyanins do not undergo changes due to ultrasound application. The preliminary results, which definitely need a depth, nonetheless allow us to hypothesize the application of ultrasound technology to accelerate the aging of red wines, which normally requires (needs) long times in the cellar conditions. Estudio preliminar de los efectos del ultrasonido en los polifenoles del vino tinto RESUMENEste estudio evalúa el efecto del ultrasonido de alta potencia (20 kHz) en la estructura fenólica de los vinos tintos, para estudiar las posibles aplicaciones de esta técnica innovadora en la maduración del vino. Se aplicaron diferentes condiciones de tratamiento con tiempos de 1, 3 y 5 minutos y amplitudes de 51, 102 y 153 µm. Bajo condiciones experimentales los principales parámetros relacionados con la evolución de los compuestos fenólicos del vino tinto mostraron variaciones interesantes; en particular, encontramos diferencias significativas en los taninos evaluados con algunos índices de reactividad de los taninos. Por otro lado, las antocianinas libres no mostraron cambios debido a la aplicación de ultrasonido. Por supuesto, los resultados preliminares necesitan profundidad, sin embargo permiten hacer hipótesis sobre la aplicación de tecnologías de ultrasonido para acelerar la maduración de los vinos tintos, que normalmente requieren (necesitan) periodos largos en condiciones particulares en las bodegas. ARTICLE HISTORY

This work focused on the study of ultrasound (US) treatment effects on wine lees, in order to verify the possibility of accelerating the protective colloids (i.e., polysaccharides) release. Moreover, these effects were compared with the usual practices of aging wine over lees and with the enzyme treatment of lees by means of betaglucanases able to demolish the glucans and facilitate the release of intracellular components. This work was performed considering the possibility of setting up a technology applicable in a cellar. Ultrasound treatment on wine lees resulted in an increase in total colloids, proteins, and polysaccharides in the medium with a reduction in the colloids particle diameter. These results were mainly correlated with treatment duration rather than its intensity. Treatment at 90 % amplitude for 3 min provided good enough results in terms of colloids release, and therefore, it was used for the comparative study with natural lysis and enzyme treatment. The parameters evaluated showed that the ultrasound treatment resulted in an increased release of colloids from yeast (polysaccharides and glycoproteins); therefore, a significant effect on the extraction of cellular components compared to the long stay on the lees was detected, indicating the interesting advantage that this new technological application can bring to the winemaking process

The effect of ultrasound (20 kHz, 153 μm) on the prefermentation extraction mechanisms in Sauvignon Blanc grapes was studied, focusing on 3-mercaptohexan-1-ol (3MH) and 4-mercapto-4-methyl-pentan-2-one (4MMP) precursors linked to glutathione (GSH) and cysteine (Cys). The treatment determined a positive extraction trend between the duration (untreated, 3 and 5 min) and the conductivity or the concentration of catechins and total phenols, significantly differentiated after 5 min. Nevertheless, the concentration of the thiol precursors in grape juice not only remained undifferentiated, but that of 3-S-glutathionyl mercaptohexan-1-ol showed a negative trend with the treatment time applied (168 ± 43, 156 ± 36, and 149 ± 32 μg/L, respectively, for control, 3 and 5 min). The divergence on the effect between families of compounds suggests an interaction between the sonication treatment and thiol precursor molecules. In order to evaluate the possible degradation properly, ultrasound was applied in a model solution spiked with 3MH and 4MMP precursors, reproducing the conditions of grapes. Except for Cys-3MH, the mean concentration (n = 5) for the rest of the precursors was significantly lower in treated samples, predominantly in those linked to glutathione (~−22% and ~18% for GSH-3MH and GSH-4MMP) rather than to cysteine (~−6%~−8% for Cys-3MH and Cys-4MMP). The degradation of precursors was associated with a significant increase of 3MH and 4MMP. The formation of volatile thiols following sonication is interesting from a technological point of view, as they are key aroma compounds of wine and potentially exploitable in the wine industry through specific vinification protocols.