Impact of dried stems in winemaking on Veneto Passito wines

Abstract

The use of stems during fermentation is generally avoided due to the herbaceous off-odors they can impart to the wine. [1]. On the other hand, nowadays some researchers and winemakers are re-evaluating their use with the aim first of all to reduce the alcohol content of wines, and secondly to enrich the wine in phenolic compounds and complexity. [1,2]. While most of the studies focused on fresh stems, this study aimed to investigate the impact of withered stems on the chemical and sensory profile of 4 Veneto passito wines, 3 red and 1 white. The grapes Corvina, Corvinone, Rondinella and Garganega were harvested in 2022 and fermented in presence of withered stems. Total polyphenols and pH were influenced by the use of stems. Nevertheless, the red wines fermented with stems presented a lower content of ethanol, probably due to the absorption of these molecules on the stems surface [3], even if only one of them was a significative difference. Regarding volatile compounds, dried stems significantly decreased methanethiol content, likely due to adsorption phenomena. Minor differences were observed in acetate esters, terpenes, and norisoprenoids, though these were not consistent across all wine types. Methoxypyrazine were found in wine in concentration well below the odor threshold, suggesting a limited release of these compounds from dried stems. Thus, this work demonstrated the potential to use withered stems on the vinification of Passito wines, on the oenological and volatile parameters.

References

[1] Blackford, M., Comby, M., Zeng, L., Dienes-Nagy, A., Bourdin, G., Lorenzini, F., Bach, B. (2021). Molecules, 26, 1240.

[2] Blackford, M., Comby, M., Dienes-Nagy, A., Zeng, L., Cléroux, M., Lorenzini, F., Bourdin, G., Bach, B. (2022). OenoOne, 56(3), 5385.

[3] Pascual, O., González-Royo, E., Gil, M., Gómez-Alonso, S., García-Romero, E., Canals, J.M., Hermosín-Gutíerrez, I., Zamora, F. (2016). J. Agric. Food Chem., 64, 6555–6566.