Reduction (cooking)

In cooking, reduction is the process of thickening and intensifying the flavor of a liquid mixture such as a soup, sauce, wine, or juice by simmering or boiling.

Reduction is performed by simmering or boiling a liquid such as stock, fruit or vegetable juices, wine, vinegar, or a sauce until the desired volume is reached by evaporation. This is done without a lid, enabling the vapor to escape from the mixture. Different components of the liquid will evaporate at slightly different temperatures, and the goal of reduction is to drive away those with lowest points of evaporation. It thus can be seen as a form of distillation, capturing those components that have the highest boiling point.

While reduction does concentrate the flavors left in the pan, reducing too much will drive away all liquid in the sauce, leaving a "sticky, burnt coating" on the pan.