Low-Pressure Nanofiltration for the Selective Reduction of Ethanol Content in Wines

Given the global shift of the wine industry toward lighter wine styles and lower ethanol content, dealcoholization of wines remains a challenging procedure in terms of selectively removing ethanol from wine samples and, at the same time, minimizing changes in selected wine quality parameters. Low-pressure nanofiltration (NF) was optimized in terms of membrane selection and NF operating conditions. The membrane displayed selective ethanol removal by NF with moderate permeation fluxes at low transmembrane pressures. Permeation tests in total recirculation mode for model solutions, followed by NF of the model and wine samples with 11.5% v/v ethanol content in concentration mode to yield a retentate, a fraction depleted of ethanol, and a permeate mainly composed of water and ethanol were performed. This fraction was subjected to evaporation for ethanol removal, and through subsequent addition to 100 mL of retentate, led to a wine with a lower ethanol content of 6.6% v/v. The use of Fourier-transformed infrared (FTIR) analysis provided a detailed understanding of the compositional changes during the concentration process. The low-pressure NF operation showed good effectiveness in alcohol reduction and high rejection coefficients to other important wine components like sugars and organic acids. These results demonstrate the applicability of NF at a volumetric concentration factor of 5 and transmembrane pressure of 5 bar in wine dealcoholization with preservation of organoleptic properties.