🍷 Cold stabilisation

Cold stabilisation is chilling wine at the winery so that salts of tartaric acid settle out before bottling. In the bottle these tartrate crystals look like broken glass or sugar. If they are removed in advance, the wine stays clear even when the bottle goes into the fridge.

According to the OIV, chilling promotes the crystallisation and precipitation of potassium and calcium tartrates, settles colloids and makes the wine more stable. Mechanical refrigeration or natural cold is used, sometimes with potassium bitartrate crystals added as seed. The crystals and colloids that drop out are then separated by physical means — racking or filtration, for example.

Cold is not the only route to tartrate stability. The OIV Code describes other treatments too: electrodialysis, cation exchangers, metatartaric acid, calcium tartrate, carboxymethylcellulose and potassium polyaspartate. All of them share one goal — to stop tartaric salts from falling out in the bottle.

The same cold works in dairying, but for a different purpose: milk is chilled so that it does not sour, wine so that the deposit drops out. For stabilisation, wine is held in refrigerated tanks or cold rooms and then carefully racked off the deposit.

Why it matters to you. Clear crystals on the cork or at the bottom of the bottle are tartrate, salts of the wine's own tartaric acid, not sugar or glass. They appear when the wine was not cold-stabilised and are especially noticeable after the bottle has stood in the fridge.