Enhancing Monastrell wine quality in a climate change scenario: the role of cation exchange resins in addressing acidity challenges

Abstract

Climate change significantly impacts vine and grape physiology, leading to changes in wine composition, including reduced titratable acidity, elevated ethanol content, and higher pH levels [1]. These effects are particularly problematic in arid and semi-arid regions such as the Mediterranean areas, where high summer temperatures and low rainfall accelerate the degradation of grape acids [2]. This results in wines lacking sufficient acidity to maintain the desired level of freshness and quality. To address this issue, the wine industry employs various techniques to reduce pH and enhance acidity, such as acid addition, ion exchange, blending with high-acidity wines, and biological methods. Among these, cation exchange resins stands out as one of the most widely used and effective approaches. For that, this study explores the effect of treating must with cation exchange resins on the composition and quality of Monastrell red wines, comparing them with wines adjusted to the same pH with tartaric acid and untreated control wines. The results showed that treating part of the must with cation exchange resins (20% and 30%) significantly lowed pH values and increased total acidity compared to the control must. This trend was also observed in wines treated with tartaric acid. The resulting wines showed no significant differences on the concentration of phenolic compounds but must acidification favored the color quality associated to an increase of the color intensity and a decrease in the tone values. Moreover, sensory analysis showed tasters preferred treated wines, particularly those made with must acidified with cation exchange resins, which were perceived as fresher in the mouth. Therefore, must treatment with cation exchange resins may be a good method for lowering the pH and increasing the acidity of Monastrell red wines solving the problem of the significant decrease in acidity that grapes are suffering due to the temperature increase in the semi-arid regions associated to climate change.

References

[1] Just-Borràs, A., Pons-Mercadé, P., Gombau, J., Giménez, P., Vilomara, G., Conde, M., Zamora, F. (2022). OENO One, 56(2), 179-192.

[2] Sweetman, C., Sadras, V. O., Hancock, R. D., Soole, K. L., Ford, C. (2014). J. Exp. Bot. 65(20), 5975-5988.