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

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 5-6times 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.