Dealcoholized wine is wine that has gone through the entire wine making process-- pressing, fermentation, and aging-- before the alcohol is removed.
Most wines are dealcoholized using a technique called "vacuum distillation", where the wine is heated under a vacuum at very low temperatures. This allows for the alcohol to evaporate at a much lower temperature than boiling it off on your stove, like when you cook with alcohol or spirits. The result is that the flavor molecules that make up the flavor notes stay intact, giving our dealcoholized wines their characteristic complexity.
Sometimes, producers may add grape juice, grape must (a crush of whole grapes), sugar, or flavoring agents back to the dealcoholized wine in order to bulk up the body or balance the flavor.
