This technique was invented in 1908 by Carl Jung, and is currently the most commonly used method for de-alcoholizing wine. It involves separating liquids based on the difference in boiling point under vacuum conditions.
Using vacuum distillation, the alcohol can be removed at a temperature of 30 degrees Celsius (instead of 78 degrees Celsius), minimizing the loss of taste. The boiling point of alcohol is lower than that of most other components in the wine, so it evaporates first.
Heat can negatively affect the aromas, so the lower the temperature, the better.
Modern vacuum distillation systems also use aroma recovery. Volatile aromas are captured and later added to the de-alcoholised wine, so that the original aromas are retained as much as possible.
Figure 1: A vacuum distillation machine.