Modulation of the tannic structure of Tannat wines through maceration techniques: cross analytical and sensory study

Abstract

The Tannat grape, native to the foothills of the Pyrenees in France, is known for producing wines with intense colour, exceptional tannic structure, and remarkable aging potential. These distinctive characteristics are attributed to its unique genome, making Tannat one of the grape varieties with the highest tannins concentration. While this contributes to the variety’s uniqueness, it also presents a challenge for winemakers, who must carefully manage maceration processes to avoid producing wines with excessively harsh tannic structures.

In response to this challenge, a study was conducted in Madiran during the 2024 harvest focusing on the vinification of a Tannat plot. The experiment was designed at the 4,6 hl scale, with three distinct maceration protocols (72h pre-fermentation maceration at 17°C (PFM), 5 days maceration at 20°C (MRac) and conventional 14 days maceration at 20°C (MT)). Throughout the vinification process, these three modalities were closely monitored, and physicochemical parameters were measured using standard methods. The Total Polyphenol Index value (TPI) was used as the determining factor to stop maceration for the three processes (20, 40, and 60 for PFM, MRac, and MT, respectively).

Following vinification, the macromolecular structure of the wines was analysed using Asymmetrical Flow Field-Flow Fractionation (AF4) [1]. The resulting fractograms clearly revealed distinct profiles corresponding to each maceration treatment, with a notable correlation between the spectra and TPI values [2]. A sensory analysis based on the TCATA method [3], allowed an expert panel to successfully differentiate the three treatments based on their astringency levels and to identify specific descriptors that characterized the perception of astringency for each modality.

These initial findings form the basis for a broader study on the macromolecules responsible for astringency. To better manage their tannic structure, the next phase of this research will explore the relationship between grape quality, vinification techniques, and the molecular compounds that contribute to the astringency of Tannat wines from Madiran.

References

[1] Marassi, V., Marangon, M., Zattoni, A., Vincenzi, S., Versari, A., Reschiglian, P., et al (2021). 433 Characterization of red wine native colloids by asymmetrical flow field-flow fractionation with 434 online multidetection. Food Hydrocolloids, 110, 106204. 435

[2] Pascotto, K., Leriche, C., Caille, S., Violleau, F., Boulet, J.-C., Geffroy, O., Levasseur, Garcia, C., & Cheynier, V. (2021). Study of the relationship between red wine colloidal fraction and astringency by asymmetrical flow field-flow fractionation coupled with multidetection. Food Chemistry, 361.

[3] Castura, J. C., Antúnez, L., Giménez, A., & Ares, G. (2016). Temporal Check-All-That-Apply (TCATA): A novel dynamic method for characterizing products. Food Quality and Preference, 47, 79–90.