Freek+: Cationic Exchange
After years of research, AGROVIN has developed the FreeK+ System: a technique for potassium reduction in wine and partially fermented must. The principle of the FreeK+ System is based on Cationic Exchange, which is the most efficient technique in removing K+.
Ionic exchange is based on the substitution of ions of the same sign between a the wine, a mobile substance, a stationary substance, and resin, using functional groups. These functional groups act as active centers capable of picking up the cations from wine (i.e. K+ and Ca+2 among others), whilst adding (H+) ions simultaneously.
Wine is a complex matrix involving a large number of compounds, macromolecules, and free ions. These elements are in a state of balance, fluctuating according to changes in environmental conditions. The replacement of cations with hydrogen ions help winemakers prevent imbalances, which could lead to issues with the bottled product.
Effective Reduction of Potassium
Selective resins in potassium (K +) allow us to eliminate other cations such as Ca2+, Fe2+, Fe3+, Cu+, Cu2+, whereby improving the stability of the wine. The exchange occurs between the metal
cations and the hydrogen ions of functional groups, having a direct effect on the pH and redox potential of wine.
Resin treatment is often followed by regeneration. Afterwards, wine passes through, washing with an HCI acidic solution, allowing the active centers to recover the
H+exchanged with the wine. This completed process allows the useful life of the resin to be unlimited, provided it is used correctly.
There are different methods to stabilize tartaric levels in wine, however, cationic exchange allows for greater longevity versus alternative solutions.
The ion potassium (K+) content found in wine contributes to its salt-saturated composition. Reducing the potassium concentration in wine means the bitartrate is not soluble, preventing it from forming deposits. The treatment will eliminate the potassium from wine, making it unnecessary to put all of the wine through the system.
Acidification of Musts and Wines
A wine’s pH level is related to different chemical and microbiological processes occurring within it. Variation in a pH level can produce varying consequences, as it affects the wine’s redox potential as well. The pH level of wine can be related to the following:
- Combination of free SO2 (affects the tonality and the microbial stability of the liquid)
- Concentration of free H+ ions
- Substitution of metal cations with protons causes an increase in total acidity and a decrease in pH
“The OIV, through resolutions Oeno 442/2012 and Oeno 443/2012; and the European Union, through the 144/2013 regulation; accept and authorize the use of the cationic exchange as an alternative method for the acidification of must and wine.”