Understanding Calcium Instability in Wine
Causes of Calcium Instability
Wine can develop instability due to calcium tartrate, or calcium oxalate forming crystals
Calcium DL-tartrate issues stem from using DL-tartaric acid with oxalic acid contamination.
Sources of Calcium
Natural calcium in vineyard soil can affect wine, with levels above 70-80 mg/L considered risky.
Excess calcium can come from using calcium carbonate or milk products during winemaking.
Older unlined concrete tanks were a historical source of calcium instability.
Crystal Characteristics
Calcium tartrate deposits appear as colorless or white crystals, often with co-deposits.
IR spectroscopy confirms calcium tartrate deposits.
Factors Impacting Precipitation
Higher wine pH levels increase the risk of calcium L-tartrate precipitation.
Winemaking processes that raise pH, like MLF and blending, can worsen instability.
Some wine components inhibit crystal formation by binding with calcium or tartrate.
Malic acid inhibits calcium L-tartrate crystallisation.
MLF can increase instability due to pH rise and a switch from malic acid to lactic acid.
Sparkling wines are more vulnerable due to lower levels of inhibitory grape pectins.
Challenges in Prediction and Stabilization
Temperature has little effect on calcium L-tartrate precipitation.
Cold tests and stabilizations are unreliable.
Seeding with micronized calcium L-tartrate may help.
Concentration product methods have limited value.
Preventing Calcium Instability
To effectively manage the risks associated with calcium instability in wine, a comprehensive approach is essential. Begin with vigilant vineyard management to control calcium levels in the grapes, aiming to keep them below 70-80 mg/L. During winemaking, avoid fining agents containing calcium and opt for alternatives. When deacidifying, use potassium bicarbonate instead of calcium carbonate to maintain acidity without introducing excess calcium. Regularly monitor and adjust the wine’s pH, as higher levels can promote calcium tartrate precipitation. Consider cold stabilization to encourage tartrate precipitation, but be aware of its limitations. Seeding with micronized calcium L-tartrate crystals can be a valuable technique when appropriately applied. If malolactic fermentation isn’t necessary, avoid it to prevent pH elevation and loss of malic acid’s inhibitory effects. Analyze the wine for calcium levels and potential instability regularly. By implementing these strategies, winemakers can minimize calcium-related risks.
Ribéreau-Gayon, P., Glories, Y., Maujean, A., & Dubourdieu, D. (2006). Handbook of Enology: The Chemistry of Wine Stabilization and Treatments. Wiley.
Zoecklein, B. W., Fugelsang, K. C., Gump, B. H., & Nury, F. S. (2014). Wine Analysis and Production. Springer.