The effect of ion-exchange resin treatment on grape must composition and fermentation kinetics

The aim of this study was to determine the influence of ion-exchange resin treatments of white grape must for the production of sparkling base wines, on the grape must chemical composition and fermentation kinetics. The experiment included an untreated grape must with a pH of 3.2, and resin-treated musts with pH 3.14, 3.07, and 3.01. Analysis of pH, total acidity, optical density (O.D.) at 420 nm, total phenolic content, tartaric acid, ammonium-nitrogen (AN) and cations (Ca²⁺, Mg²⁺, Cu²⁺, K⁺, and Na⁺) was performed. The fermentations were monitored by mass reduction (CO₂ release g/L), and fermentation parameters obtained from a modified non-linear sigmoidal equation. The analyses of the musts showed differences in the concentration of metals, total acidity, tartaric acid, AN and O.D. 420 nm. The kinetic parameters of the fermentation showed significant changes between the control must and the ion-exchange treatments. This study showed that the treatment with cationic resins at the tested level significantly affects the chemical composition of the musts, interfering with the fermentation kinetics. In addition, reductions in the must pH index close to 0.1 unit can lead to positive results in the characteristics of the base must of sparkling wines.