The use of cation exchange resins (CER) in acid cycle produces a reduction of wine pH, by exchanging cations such as potassium (K+) for hydrogen ions (H+). During the process, the removal of K+ and calcium ions (Ca2+) may also result in a decreased formation of tartrate salts. Like so, the lower pH and partial removal of metal catalyzers (e.g. iron) could improve the oxidative stability of wines, as measured by the loss of free sulfur dioxide (SO2), and the absorbance of light at 420 nm. Therefore, the aims of these trials were: To optimize the exchange process for pH reduction, by evaluating the efficacy of using different volumes and concentrations of acid during the activation of the resins (i.e. sulfuric acid, H2SO4); and evaluate the formation of tartrate salts and oxidative stability of the treated wines. The study encompassed a series of winery and laboratory scale trials in which some of the following results were obtained: The amount and concentration of H2SO4 solution, recommended by the vendor of the technology, was reduced by more than 50%, with similar efficacy results. The CER treated wines showed a significantly lower pH, lesser concentration of cations (e.g. K, Ca and Fe) and tartrate salts, and a significant increase in titratable acidity and free SO2. The ion exchange treatment also caused a positive effect on the oxidative stability of the wines, in which a slower increase in the absorbance at 420 nn was observed. To further explain the later result, a separate experiment in which the effect of metal catalizers, pH, and their combination were evaluated againts wine oxidation.

Acidity adjustments, tartrate formation, and oxidative stability of wines treated with cation exchange resins

254th National Meeting (2017)

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