What are Wine “Deposits”?

Often in wines, especially when talking about red wines and a few years after the harvest, imperfections can be identified during the visual examination due to residual substances or sediments, commonly called “posa” for their characteristic of settling at the bottom of the bottle.

The formation of these deposits is caused by a natural process that occurs due to the aggregation and subsequent precipitation of solid substances present in the liquid solution of the wine, which settle at the bottom of the bottle.

The characteristics of these substances vary depending on the type of wine, its production process, and the maturation/aging it has undergone.

In red wines, deposits can form when grape pigments – anthocyanins – as well as some aromatic substances, aggregate into flakes, subsequently settling at the bottom of the bottle. When this happens, there will also be a change in the color of the wine and its aroma.

Calcium or potassium tartrate crystals, on the other hand, form when the wine undergoes sudden temperature changes, for example during the cooling process. This leads to the precipitation of small particles of calcium sulfate or tartrate salts, which always settle at the bottom of the bottle.

The presence of these crystals does not create any problems for the integrity of the wine; rather, it indicates that the wine has undergone very few treatments.

Even during fermentation, yeast cells and fermentation cellular residues can settle, especially if the wine has not been completely clarified or filtered. Proteins and tannins contained in some wines can also precipitate over time, particularly when no clarification or complete filtration has been performed.

The formation of deposits can be influenced by various factors, including the grape variety, winemaking techniques, the clarification and filtration process, and the wine’s storage conditions.

When “deposits” are present, they accumulate at the bottom of the bottle as residual sediments and appear as small debris or as a haze, varying according to the quantity and type of substances they are composed of.

To minimize the visual impact of the deposits during tasting, it is advisable to handle the bottle carefully, avoiding even minimal shaking, so that the residues remain as united and compact as possible at the bottom of the bottle.

For older wines or those with particularly evident residues, it is common practice to decant the wine, i.e., to pour it into a decanter or any other container, preferably after having allowed it to breathe, thus separating the sediments from the wine and allowing for a clearer drink.

It is important to remember that the residues we have discussed, although they may be visually disturbing, are not necessarily indicative of a flawed wine.

On the contrary, in some cases, they are considered signs of authenticity and can even add complexity to the wine, especially in the more mature ones.

Therefore, we suggest paying close attention to the wines you are drinking, focusing on the residues that may be present inside a bottle. These should not necessarily be considered as problems with the wine or actual defects, but rather as a characteristic sign of the wine’s quality and terroir.

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