Characterization of Low-Alcohol Wines Obtained by Post-Fermentative Reverse Osmosis and Vacuum Concentration

In the context of climate change and the general trend toward a healthy lifestyle, reducing the alcoholic strength of wines poses a major challenge for producers. In order to obtain quality low-alcohol wines (LAWs), Muscat Ottonel conventional wine was subjected to reverse osmosis followed by vacuum concentration of the hydroalcoholic permeate (ROVC) or to two-step vacuum concentration (TSVC), with the recovery of aromas as the first alcoholic fraction (F1). Beverages with alcoholic concentrations of 3.50, 5.50, and 8.50% vol. were obtained, with compositional characteristics and sensory properties varying significantly with alcoholic strength and dealcoholization technique applied. ROVC produced wines with organic acids, volatile constituents, extract, and color intensity decreasing progressively with the reduction in alcohol concentration. At similar alcohol concentration, TSVC LAW showed a significantly higher phenolic content, antioxidant activity, volatile compounds (including esters and terpenes), and overall structural balance, maintaining better the typicity of wines. In both processes, reducing alcohol below 5.50% vol. significantly affected the quality and acceptability of the final product. Hierarchical cluster analysis indicated that TSVC LAWs were statistically closer to the conventional wine (control). These findings improve the understanding of how dealcoholization technologies affect the composition of wine, improving product quality, sustainability, and operational efficiency.