Tartaric acid
Tartaric acid is the principal organic acid found in grapes and wine and one of the defining chemical components of wine acidity. It is naturally present in high concentrations in Vitis vinifera berries and remains relatively stable throughout ripening and fermentation, making it a key contributor to wine freshness, structure and chemical stability.[1]
Occurrence in grapes
[[Tartaric acid]] accumulates early in grape development and, unlike malic acid, is only minimally metabolised during ripening. Its concentration is therefore less sensitive to temperature and respiratory loss, although dilution may occur as berries increase in size. Levels vary by grape variety, site and vintage, but tartaric acid is typically the dominant acid in ripe grapes from temperate and warm climates.[2]
Because tartaric acid is rare in other fruits, it is considered a chemical marker of grape-derived products and plays a central role in distinguishing wine acidity from that of other fermented beverages.
Role in wine chemistry
In wine, tartaric acid contributes significantly to total acidity and pH buffering. Its dissociation behaviour influences microbial stability, colour expression in red wines and the perception of freshness on the palate. Tartaric acid also forms salts with potassium and calcium, which can precipitate as crystalline deposits under certain conditions.[3]
These precipitates, commonly known as tartrate crystals, are chemically harmless but may be perceived by consumers as a fault if they appear in bottle. Their formation is influenced by temperature, alcohol level, pH and potassium concentration.
Tartrate stability
The tendency of tartaric acid to form insoluble salts is a major consideration in winemaking. Wines that are not tartrate-stable may develop crystalline sediment after bottling, particularly when exposed to cold storage. To prevent this, producers often employ stabilisation techniques such as cold stabilisation or electrodialysis to remove excess potassium bitartrate prior to bottling.[4]
The management of tartaric acid and its salts is therefore closely linked to wine clarity, stability and shelf appearance rather than sensory quality alone.
Adjustments and oenological use
Tartaric acid is widely used in winemaking to adjust acidity, particularly in warm-climate regions where natural acid levels may be low. Acidification with tartaric acid is generally preferred over other acids because it is naturally present in grapes and has predictable chemical behaviour in wine.[5]
Regulations governing acidification vary by country and appellation. The OIV permits the use of tartaric acid for acidity adjustment within defined limits, and it remains the most commonly authorised acid for this purpose worldwide.[6]
Sensory impact
Although tartaric acid contributes less directly to sharpness than malic acid, it provides a firm, linear acidity that supports structure and balance. Wines high in tartaric acid tend to show greater perceived freshness and ageing potential, particularly when combined with adequate phenolic and alcohol balance.[7]
The interaction between tartaric acid, alcohol and phenolic compounds is central to overall wine harmony rather than being perceived in isolation.
See also
References
- ↑ Jancis Robinson, Oxford Companion to Wine, Oxford University Press, 17 Sept. 2015. ISBN 9780198705383.
- ↑ PhD Jackson, Ronald S., Wine Science: Principles and Applications, Academic Press Inc, 14 April 2020. ISBN 9780128161180.
- ↑ Pascal Ribéreau-Gayon, Yves Glories, Alain Maujean, Denis Dubourdieu, & 1 more, Handbook of Enology, Volume 2: The Chemistry of Wine - Stabilization and Treatments, Wiley, 31 Mar. 2006. ISBN 9780470010372.
- ↑ Andrew L. Waterhouse, Understanding Wine Chemistry, Wiley, 19 Aug. 2016. ISBN 9781118627808.
- ↑ Peynaud, Knowing and Making Wine, Wiley, 1984, ISBN 9780471881491.
- ↑ OIV, “Organic acids in grape must and wine”.
- ↑ Roger B. Boulton, Vernon L. Singleton, Linda F. Bisson, Ralph E. Kunkee, & 1 more, Principles and Practices of Winemaking, Springer, 31 Oct. 1998. ISBN 9780834212701.