Federico Casassa, Karina Garro,* Santiago Sari, Martin Fanzone, Anibal Catania, and Sebastian Gomez-Talquenca  
*Centro de estudios enológicos, Estación Experimental Mendoza, Instituto Nacional de Tecnología Agropecuaria (EEA Mendoza INTA), San Martín 3853, M5528AHB, Luján de Cuyo, Mendoza, Argentina, Mendoza, Argentina
(garro.karina@inta.gob.ar)

The final wine tannin concentration is contingent not only upon the original tannin content in the grapes, but also on the amount of effectively extracted tannins, which may be regulated by tannin-cell wall interactions during winemaking. Anecdotal evidence shows that Bonarda wines (syn. Charbono) are inherently low in tannins, suggesting lower tannin retention rates than Malbec, in which tannin retention is not problematic. Here we hypothesized that application of saignée (removing a portion of the must prior to alcoholic fermentation) may result in partial removal of cell wall material, thereby furthering tannin retention. We studied the individual and comparative effects of several modified saignée treatments on the chemical and sensory properties of Bonarda and Malbec wines. The grapes were processed using four different saignée techniques, targeted at modifying 16% of the total volume, including regular saignée (S), saignée paired with an equal volume of water addition (WS), saignée paired with an equal volume of must from Red Globe (a table grape cultivar; MS), and transfusion, which consisted of parallel fermentation of the removed juice and a posterior reincorporation of it postfermentation (TS). A control without saignée was also included, with all treatments performed in triplicate in 100 L fermentors. Only S and TS applied to Bonarda enhanced tannin concentrations above that of control wines, consistent with the cell wall hypothesis. For Malbec, the treatments had no positive effect on tannin concentration relative to control wines. A two-way ANOVA including chemical data identified significant (p < 0.05) treatment × cultivar interaction for wine tannin concentration, indicating a possible effect of cell wall material on tannin extraction in Bonarda grapes. From a sensory standpoint, S and TS Bonarda wines were perceived as significantly more astringent, while for Malbec, this was true for control and MS wines.

Funding Support: Instituto Nacional de Tecnología Agropecuaria (INTA)