Why wine crystallizes

However, for white wines which are often refrigerated before serving, these tartrate crystals may be alarming. Tartrate crystals in white wine have been described as having a similar appearance to shards of glass or have been mistaken for unwanted or unnatural sediment — this is simply not the case.

Though their appearance may be a bit off-putting, tartrates are completely harmless. Cold Stabilization: negative effects on wine Some winemakers choose to cold stabilize their wines to eliminate the future formation of tartrate crystals. Cold stabilization is the process of cooling the wine to around freezing temperatures in large stainless steel tanks for several days or weeks after the wine has aged and just before bottling.

By cooling the wine prior to bottling, the potassium bitartrates will crystalize and drop to the bottom of the tank where they can then be filtered out of the wine. By doing this, the winemaker is ensuring that further tartrate crystals do not form in the bottle mainly for aesthetics reasons.

This came from the observation that wines aged on the lees, which are the sediment of mostly dead yeast cells left after fermentation, are less likely to develop tartrate crystals after bottling.

Another method, electrodialysis, passes the wine against an electrically charged membrane in a sophisticated filtration unit. There are two reasons for this. Most high-quality red wines are aged on their lees for at least a few weeks. White wines, though, are aged on their lees less often. But the other form of sediment, lees or dregs, is almost always a red-wine phenomenon. Winemakers use whole crushed grapes—the skin, juice, seeds and pulp—to make red wine. Only the juice and pulp are used to make white wines.

Red wine gets most all of its color and much of its aroma, flavor and texture from the skins. Because of this, red wine has more grape particles suspended or dissolved in it. A new wine is full of skins, seeds and bits of stems, as well as used-up yeast cells from the fermentation process.

And is sediment even something to worry about it, or avoid? Those lovely tannins, which give the wine its structure and body, come from the stems, seeds and skins of the fruit, and the winemaking process used for red wines involves the pulverization of all those parts of the plant.

Sadly, this is no longer done by the stamping feet of fair maidens, but rather by machine. Nonetheless, the purpose is the same — by crushing all these things together, the fermentation gets a kick start, and the wine begins to take on the layers of complexity, acid, tannin and fruit juice it needs to do its thing. They are suspended in the liquid, and not visible as they will be far too small to detect.

However, give your wine a bit of time and a quiet place to sit and settle, and eventually, all those pieces of stem, seed and skin will gather together, and slowly sink to the bottom. What happens if you accidentally drink a bit of sediment? The good news? Wine with sediment gives you a perfect excuse to get your decanter out from the cabinet, as this is the easiest way to remove it when pouring.

The liquid is chilled to near-freezing in tanks, causing the crystals to precipitate out of the solution. Some wineries chill reds prior to bottling, too, anticipating that even a red wine can be inadvertently exposed to low temperatures during transport. Though they can be off-putting to consumers who may be puzzled, the crystals are in fact an encouraging sign. Makers of high-quality wine prefer to intervene as little as possible with such techniques as cold stabilization and filtering, which can strip wine of subtle flavours.