Dealcoholization of wine by pervaporation

This study presents the production of low-alcohol wines (white, red, and rosé) using a lab-scale pervaporation (PV) membrane setup. Initial tests with ethanol-water mixtures were conducted to validate the performance of a commercial dense flat-sheet polymeric composite membrane (Pervap™ 4060, supplied by DeltaMem AG) against literature data and to examine the influence of temperature (T) and permeate-side vacuum pressure (p _perm ) on process performance. Membrane performance was assessed in terms of ethanol flux, ethanol/water separation factor, and ethanol permeance. Owing to its sensitivity to color changes, white wine was used in preliminary tests to optimize the operating conditions (T and p). The optimized conditions were then applied to the partial (≈ 7.5 vol.%) and total (≈ 1.0 vol.%) dealcoholization of all three wine types. Losses of volatile organic compounds through the membrane were evaluated by gas chromatography-mass spectrometry (GC-MS). PV tests with synthetic ethanol-water mixtures yielded results consistent with literature values. Experiments with white wine showed that higher temperatures (i.e., 60 °C) substantially increased the permeate flux (0.13 kg h^-1 m^-2 vs. 1.72 kg h^-1 m^-2, at 13-17 °C and 60 °C respectively) but had a negative effect on the wine's visual appearance. Therefore, PV tests with red and rosé wines were carried out at lower temperatures (13-17 °C). Overall, total dealcoholization of the three wine types resulted in relatively low average ethanol permeances (0.43-0.59 mol m^-2 h^-1 kPa^-1) and extended processing times (209.5-234.7 h). In contrast, partial dealcoholization led to higher average permeance values (1.43-1.56 mol m^-2 h^-1 kPa^-1), highlighting its greater efficiency. GC-MS analysis showed that partial dealcoholization retained 20-60% of key esters in white and red wines, with substantially lower aroma losses compared to total dealcoholization. These results suggest that white and red wines are the most promising candidates for pervaporation-based dealcoholization. Pervaporation technology shows considerable potential for the production of partially dealcoholized wines, offering a sustainable and relatively quality-preserving alternative for the wine industry. Nevertheless, further research is needed to develop strategies that minimize the loss of volatile aroma compounds.