Precision Enology Strategies to Enhance the Quality of Red Wine Color: The Synergistic Effect of pH and Selected Exogenous Grape Seed Tannins

Acidification and the application of exogenous tannins are well-established oenological practices designed to ensure wine stability and quality, playing a pivotal role to address the grape compositional imbalances associated with climate change. This study investigates precision enology techniques using a 2023 Sangiovese di Romagna, analyzing the interaction between pH modulation (3.2, 3.6, 3.8) and the addition of commercial grape seed tannins with varying medium degrees of polymerization (TanA: 3.1 mdp vs. TanB: 10.8 mdp). Following alcoholic fermentation, a full factorial design was implemented, including control batches (pH adjustment only). After a 40-day mild thermal treatment (T = 25 ± 1 °C) to simulate aging, results indicate that the high-mdp tannin (TanB) dominated color evolution regardless of pH, whereas the low-mdp tannin (TanA) effect was pH-dependent. Notably, a pH of 3.8 resulted in colloidal instability across all samples. The findings highlight the importance of customized protocols to mitigate climate-related challenges in winemaking.