Cold Stabilisation
A winemaking process in which wine is chilled to near-freezing temperatures to precipitate tartrate crystals before bottling, preventing them from forming in the bottle.
In depth
Grapes naturally contain tartaric acid, and at low temperatures, tartaric acid can combine with potassium or calcium to form tartrate crystals — most visibly potassium hydrogen tartrate (cream of tartar). These crystals are harmless and tasteless but can alarm consumers who mistake them for broken glass.
To prevent crystals forming in the bottle, winemakers chill the wine to around -4°C to -5°C for several days or weeks. The tartrates crystallise and precipitate out of solution, and are then removed by filtration or racking. The wine is then stable at refrigerator temperatures.
Many consumers find tartrate crystals concerning, so commercial producers routinely cold-stabilise. However, the process can slightly strip wine of flavour compounds and aromas. Natural wine and minimum-intervention producers often skip cold stabilisation, accepting that crystals may form — some consider them a sign of minimal processing.
Alternatives include adding metatartaric acid (temporary stabilisation), mannoproteins, or using electrodialysis.
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Frequently asked questions
- Are tartrate crystals in wine a fault?
- No. Tartrate crystals (sometimes called "wine diamonds") are harmless potassium or calcium tartrate precipitates that form when wine gets cold. They are odourless and tasteless, and are a sign of minimal processing rather than a fault. They are not to be confused with broken glass.
- Why do some winemakers skip cold stabilisation?
- Cold stabilisation can strip some flavour compounds from wine. Producers working in a minimal-intervention or natural wine style often skip it to preserve more character, accepting that harmless tartrate crystals may form in the bottle when stored cold.
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Practise questions on this topic
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