Reduction (Cooking)

Reduction thickens a liquid and concentrates its flavor by simmering or boiling it uncovered, commonly applied to soups, sauces, wine or fruit juice, so that water and other volatile components evaporate off as vapor while the liquid's remaining solids and flavor compounds become more concentrated. Because different components of the liquid evaporate at different temperatures, a slow reduction, sometimes carried out over one to ten hours in classical French technique, develops a fuller, more complex flavor than a fast, hard boil, and it also lets a cook skim off impurities as they rise. Reduction is used to make consommes, gravies, gastriques, pan sauces and dessert syrups, but taken too far it can leave a sticky, burnt residue on the pan, so the liquid needs regular stirring and attention as it cooks down.