WHY BITARTRATE CRYSTALS ARE FORMED?

Bitartrate crystal formation occurs due to the presence of tartaric acid in wine, a substance that occurs naturally in grapes along with potassium.
Normally, these two elements are maintained in dynamic equilibrium in both must and wine. However, when there are changes in certain factors that affect this balance, tartaric acid reacts with potassium, forming crystals that can precipitate to the bottom of the bottle. In this image we can see the crystals on the inner wall of a white wine goblet:

The main variations that can trigger this reaction are.:

• changes in temperature;
• changes in alcohol concentration;
• changes in sugar concentration;
  fluctuations in pH.

IS THE PRESENCE OF TARTARIC ACID IN WINES REALLY A PROBLEM?

First of all, it is crucial to understand that the presence of bitartrate crystals in wine does not indicate poor product quality at all. These crystals may form occasionally due to the natural interaction between tartaric acid and potassium present in grapes.

Although the presence of bitartrate crystals does not adversely affect the taste or quality of the wine, some consumers may find them aesthetically unappealing. In addition, the presence of these crystals could generate concerns or doubts about possible wine defects or added chemicals.

For those who wish to avoid the presence of bitartrate crystals in wine, some preventive measures can be taken. One of these is decanting the wine, a process that allows the crystals deposited at the bottom of the bottle to be separated from the wine itself. Alternatively, you may choose to discard the portion of the wine in which the crystals are present, although you should be aware that this choice involves some loss of product.

In any case, it is important to be informed and aware that the presence of tartaric acid and, consequently, bitartrate crystals, is a natural phenomenon and does not compromise the integrity and quality of the wine.

THE ROLE OF TARTARIC STABILIZATION OF WINE

Tartaric stabilization is an oenological practice that aims to prevent the formation of potassium bitartrate crystals in white and red wines during storage.

The goal of stabilization is to accelerate the precipitation of tartaric acid salts through multiple steps:

1. Nucleation: this is the formation of crystals according to the degree of saturation of the wine;
2. Accretion: the more or less regular growth of crystals;
3. Precipitation of the potassium bitartrate salts;
4. Elimination: the salts are removed from the liquid.

METHODS OF REMOVING POTASSIUM BITARTRATE

To achieve tartaric stability, there is a choice between natural processes and the use of specific additives. Among the additives we can include:

• metatartaric acid;
• the cellulose gums (carboxymethylcellulose CMC);
• the mannoproteins;
• the polyaspartate.

However, since 2012, the European Union has restricted the use of chemical additives in tartaric stabilization. In addition, as of Dec. 8, 2023, labeling of ingredients and nutrition declaration of wines will be mandatory.

Faced with these new regulations, many wine producers have veered toward more natural solutions, such as:

• the cooling of the wine, to promote the precipitation of bitartrate crystals;
  
• The selection of specific yeasts, which help remove potassium bitartrate from the wine; and. 

The natural elimination of potassium bitartrate

Natural tartaric stabilization, which removes bitartrate, is usually done by chilling: the wine is chilled at temperatures from 0°C to -4°C for a few days or a few hours, depending on the system used.

This operation allows the bitartrate crystals to precipitate, which will then be removed. This practice, if done only in refrigerated tanks, can be time-consuming and expensive.

This problem is solved by TMCI Padovan’s Kristal Stop continuous tartaric stabilization plant. Through the integrated rapid cold system, the K-Stop plant allows very short treatment times of 90 to 270 minutes.

Made in models from 2 to 20 t/h, the plant can be built with higher capacity options upon request.

The advantages of this machine are many:

• flexibility: it is possible to temporarily stop or reduce product flow without burdening production.
• automation: continuous monitoring throughout the stabilization phase, adjustable through a PLC that allows customization of the various stabilization and washing cycles.
• labor savings: due to the high automation of the system.
• effectiveness: the system provides for continuous detection of the conductivity of the output product after treatment and automatic recycling if set stabilization levels are not reached.

To conclude…

As we saw above, tartaric stabilization is an important step in improving the aesthetic quality of wine and thus its perception by consumers.

Thanks to the K-Stop plant, tartaric stabilization proves to be a natural and economical way to eliminate potassium bitartrate crystals, ensuring a higher quality product. The use of this plant allows wineries to comply with new European regulations, reducing the use of chemical additives and ensuring consumer-friendly labeling.

Choosing K-Stop for potassium bitartrate removal not only improves the appearance of wine, but also contributes to a more sustainable and environmentally friendly wine industry. In addition, K-Stop’s advantages in flexibility, automation, savings, and efficiency make it an excellent choice for those seeking to improve the quality of the final product, strengthening consumer confidence.