Comparison of the physicochemical and volatile composition of wine fractions obtained by two different dealcoholization techniques

- Membrane contactor and vacuum distillation were used for wine dealcoholization.
- Polyphenols concentration increased in the wine fractions dealcoholized at 5% v/v.
- No precipitation of potassium bitartrate was observed during dealcoholization.
- The main compositional modifications occurred with the wine aroma compounds.
- Using the fractions to dealcoholize wines by 2% slightly modified the δ18O ratio.

Three wines (a Rosé wine, a Pelaverga and a Barbera red wines) were dealcoholized at 5% v/v ethanol with two different techniques: membrane contactor (MC) and distillation under vacuum (D). The influence of the treatments on the physicochemical composition and aromatic profile of the dealcoholized fractions was investigated. The main difference between the two techniques was the concentration grade reached by the dealcoholized fractions, which was 5-6 times higher with D than with MC due to the concomitant loss of water. The main fixed compounds (organic acids, cations, polyphenols, anthocyanins) were not lost during the dealcoholization, while the losses of volatile compounds were relevant. Finally, the δ18O isotopic ratio was studied. The δ18O isotope ratio increased with D and decreased with MC. At the same time the δ18O isotope ratio fell within legal limits when the final ethanol content was adjusted to 2% by blending with dealcoholized fractions.